 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| PhotoKB HomeDiscussion Groups Digital Photography Digital PhotoDSLR CamerasZLR CamerasPoint & Shoot CamerasFilm Photography 35 mmLarge FormatMedium formatDarkroomFilm and LabsOther EquipmentPhoto Technique Nature PhotographyPeople PhotographyTechnique GeneralGeneral Photo Topics General TopicsAustralian PhotographyUK PhotographyDirectoryPhoto Clubs |
Photo Forum / Digital Photography / DSLR Cameras / January 2005New 20D needs lenses
Santa was very good and brought a 20D. Now the next challenge is what lenses to buy? My subjects will be the family holiday pictures and this years Rose Parade and Rose Bowl Game (50 yard line seats!). I am so enjoy Yosemite type scenery. Any ideas and suggestions would be appreciated. > Santa was very good and brought a 20D. Now the next challenge is what > lenses to buy? My subjects will be the family holiday pictures and this > years Rose Parade and Rose Bowl Game (50 yard line seats!). I am so enjoy > Yosemite type scenery. > > Any ideas and suggestions would be appreciated. Since you didn't give us a budget, and want to hit the football shots... http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=1 62616&is=USA Now, back to budgets of mortal proportions. As for family holiday pictures, I really, really like my Sigma 28-105 f/2.8: http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=1 29503&is=USA Sharp, good pictures, and the 2.8 f-stop helps both with softening the background of portraits, and letting in lots of light in indoor settings if you don't have a good flash. With the 20D, that will come out to the equivalent of about a 45-170mm. I was worried that I would miss the wide-angle shots, but I have to say that my Canon 18-55 just sits in the bag, and is never missed. : ) For the longer shots, I've used a Sigma 70-300 macro-capable lens for just a few minutes, and found nothing wrong with it upon a superficial inspection of the shots: http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=1 63657&is=REG The equivalent on the D20 would be 112-480, which is pretty long. In macro mode, the minimum focal distance is something like 3 feet (more like 6-10 at max zoom, if I recall), but with an equivalent 480mm focal length, it doesn't take much to fill the frame. I thought about the Sigma 18-125 DC lens (made for the APS-C sensor, no crop factor), but there were a lot of reports of vignetting, and the smallest aperture is 3.5. If you have a good flash, that shouldn't be a problem - but if you're only using the flash on the camera, every f-stop counts. steve > Now, back to budgets of mortal proportions. As for family holiday > pictures, I really, really like my Sigma 28-105 f/2.8: [quoted text clipped - 23 lines] > > steve I bought that Sigma 28-105 f2.8-4 for my wife for Christmas a few years ago, it was the single worst lens I have ever seen in my photographic life. It gave new life to the term soft. And for the price of the Sigma 70-300, you can buy the Canon 75-300 USM, a better lens.  SignatureSkip Middleton http://www.shadowcatcherimagery.com > I bought that Sigma 28-105 f2.8-4 for my wife for Christmas a few years ago, > it was the single worst lens I have ever seen in my photographic life. It > gave new life to the term soft. And for the price of the Sigma 70-300, you > can buy the Canon 75-300 USM, a better lens. There's also a much cheaper 28-105 f/3.8 lens, but I'll assume that you really had the f/2.8 model. In any event, the two that I have used have both produced sharp, clear images when I and the camera have done our parts - but I don't doubt that you had a bad experience with yours. Without having the two lenses in question to fiddle with, there's not much I can say. : ) As for canon-vs-sigma in the 75-300 models, the canon doesn't have a macro capability, but that's a side concern. I'd love to hear in which ways the Canon lens has worked out better for you than the Sigma, as I may be purchasing a lens of that range soon. steve Just one small point, even though the 18-125 is made for digital, the designation is still as per normal lenses. On an APS-C sensor the lens is actually 28-200. if you like Canon try... 28-135, 17-40, 50 f1.8, 85 f1.8 , 400 f5.6 (or 100-400 which doesn't get quite as good comments) > Santa was very good and brought a 20D. Now the next challenge is what > lenses to buy? My subjects will be the family holiday pictures and this > years Rose Parade and Rose Bowl Game (50 yard line seats!). I am so enjoy > Yosemite type scenery. > > Any ideas and suggestions would be appreciated. > if you like Canon try... > > 28-135, 17-40, 50 f1.8, 85 f1.8 , 400 f5.6 (or 100-400 which doesn't get > quite as good comments) 28-135 USM IS ? That piece of junk ? But agree on the rest of your list... That lens is not piece of junk. Do you actually have any experience of it? I have 16x20s with that lens that are great, 13x19s that are outstanding. http://www.shutterspeedway.com/cgi-bin/gallery.cgi?user=SkipM&gallery=My%2020D%2 0images/Day%20at%20the%20Races&picture=21 SignatureSkip Middleton http://www.shadowcatcherimagery.com > >> if you like Canon try... [quoted text clipped - 5 lines] > > But agree on the rest of your list... Skip, The guy is a basher. He also called the EF-S 17-85mm IS lens a piece of junk. Obviously does not own any equipment or has any experience with Canon EOS system. Please ignore his posts. BTW, love the shots. Musty. > That lens is not piece of junk. Do you actually have any experience of it? > I have 16x20s with that lens that are great, 13x19s that are outstanding. http://www.shutterspeedway.com/cgi-bin/gallery.cgi?user=SkipM&gallery=My%2020D%2 0images/Day%20at%20the%20Races&picture=21 > >> if you like Canon try... > >> [quoted text clipped - 4 lines] > > > > But agree on the rest of your list... Thanks! I figured him for a basher, but wanted to set the record straight for the OP. SignatureSkip Middleton http://www.shadowcatcherimagery.com > Skip, > [quoted text clipped - 22 lines] >> > >> > But agree on the rest of your list... > Thanks! > I figured him for a basher, but wanted to set the record straight for the > OP. I am fairly new to the DSLR and DigiCam newsgroups, but I am appalled at the amount of bashers especially in regard to the 20D. The funny thing is that when you hear from actual owners, they are very happy. Having said that, there are also some very knowledgable posters, so overall it is a positive experience. BTW, that was a Maserati, right? > > Skip, > > [quoted text clipped - 10 lines] > > it? > >> I have 16x20s with that lens that are great, 13x19s that are outstanding. http://www.shutterspeedway.com/cgi-bin/gallery.cgi?user=SkipM&gallery=My%2020D%2 0images/Day%20at%20the%20Races&picture=21 > >> >> if you like Canon try... > >> >> [quoted text clipped - 5 lines] > >> > > >> > But agree on the rest of your list... >> Thanks! >> I figured him for a basher, but wanted to set the record straight for the [quoted text clipped - 8 lines] > > BTW, that was a Maserati, right? Yep, the trident is a dead giveaway. A6GC, I believe. SignatureSkip Middleton http://www.shadowcatcherimagery.com Excuse top posting, nice shots my friend. > That lens is not piece of junk. Do you actually have any experience of > it? I have 16x20s with that lens that are great, 13x19s that are [quoted text clipped - 10 lines] >> >> But agree on the rest of your list... Sorry, forgot to move my replies to the bottom, now we've made a mess of this thread, haven't we? <G> Thanks for the compliment, but I had some great things to photograph, that day! SignatureSkip Middleton http://www.shadowcatcherimagery.com > Excuse top posting, nice shots my friend. > [quoted text clipped - 13 lines] >>> >>> But agree on the rest of your list... > That lens is not piece of junk. Do you actually have any experience of it? > I have 16x20s with that lens that are great, 13x19s that are outstanding. http://www.shutterspeedway.com/cgi-bin/gallery.cgi?user=SkipM&gallery=My%2020D%2 0images/Day%20at%20the%20Races&picture=21 I would agree that it's not a piece of junk, but my experience of it (had one for a year or so) is that it's not the sharpest lens going. I was glad to get rid of mine. Lenses I've used and would recommend.... Canon 50mm f1.8 - an absolute bargain. Canon 17-40L f4 - very good wide to standard zoom. Makes a good carry around lens for 10D or 20D Canon 70-200L f4 - A beauty of a lens. Light enough to handhold easily. Sharpness is excellent for a zoom and background blurs out beautifully. Canon 400L f5.6 - Tack sharp. I've had good results handholding this one. Great value long lens when used on 10D or 20D. Sigma 50mm f2.8 macro - I haven't used the Canon macros so I can't compare, but I've been happy with the results from this on. It's sharp. Hopefully I'll be able to add the 135L f2 to this list in the next few days :-) Lenses to avoid imho... Canon 75-300 f4-5.6 - the greatest piece of junk I've ever had the misfortune to possess. Canon 28-135IS - not particularly sharp, build quality isn't great, IS is slow and not particularly useful given the focal range. SignatureColm Care to elaborate on your comments about the 28-135 IS. I've been reasonably pleased with it thru-out all lengths and apertures. Steve >> 28-135, 17-40, 50 f1.8, 85 f1.8 , 400 f5.6 (or 100-400 which doesn't get >> quite as good comments) > > 28-135 USM IS ? That piece of junk ? > > But agree on the rest of your list... >>if you like Canon try... >> [quoted text clipped - 4 lines] > > But agree on the rest of your list... One mans trash is another mans treasure. The 28-135 is a good lens to have. nick >> 28-135, 17-40, 50 f1.8, 85 f1.8 , 400 f5.6 (or 100-400 which doesn't get >> quite as good comments) > >28-135 USM IS ? That piece of junk ? Has anyone really looked at the quality of the digital sensor on the dSLR's to determine at what point buying better glass doesn't make any difference? The 28-135 IS is a great lens for what it does. -Joel ---------------------------------------------------------------------------- Please feed the 35mm lens/digicam databases: http://www.exc.com/photography ---------------------------------------------------------------------------- >Has anyone really looked at the quality of the digital sensor on the >dSLR's to determine at what point buying better glass doesn't make any >difference? The 28-135 IS is a great lens for what it does. Better glass is always better, unless your camera is lacking an anti-aliasing filter, like the Sigmas SDs and the Kodak 14MP cameras. Even if the camera's pixel spacing and AA filter play an important role in limiting resolution, a better lens will give better pixel-to-pixel contrast as well as truer overall contrast. Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< >28-135, 17-40, 50 f1.8, 85 f1.8 , 400 f5.6 (or 100-400 which doesn't get >quite as good comments) Also, depending on how large you intend to print the final pictures, you may not need such a long lens. If you only want 4x6 or even 8x10, you can crop the digital image (effectively bringing you closer to the action) and still get a good shot with a shorter lens. -Joel ---------------------------------------------------------------------------- Please feed the 35mm lens/digicam databases: http://www.exc.com/photography ---------------------------------------------------------------------------- > Santa was very good and brought a 20D. Now the next challenge is > what lenses to buy? My subjects will be the family holiday pictures > and this years Rose Parade and Rose Bowl Game (50 yard line seats!). > I am so enjoy Yosemite type scenery. > > Any ideas and suggestions would be appreciated. I have the Canon "L" series 17-40 F4 and it is a wonderful lens. I couldnt give a higher recommendation. It replaced a Smegma (Sigma) 15-30 that I owned for 1 week. Pure crap optics on that one. Lens flare, fall-off. Ugh. never again that brand for me. > Santa was very good and brought a 20D. Now the next challenge is what > lenses to buy? My subjects will be the family holiday pictures and this > years Rose Parade and Rose Bowl Game (50 yard line seats!). I am so enjoy > Yosemite type scenery. > > Any ideas and suggestions would be appreciated. Have you considered the EF-S IS 17-85mm f/4-5.6 ? It has excellent range, the IS is wonderful and the pictures come out very sharp. It is also lighter than say the 17-40 f/4L. It is built for Canon 20D. I also recommend the 70-200mm f/4L which is great value under $600. If you can spend extra $$'s, you can get the IS version which would be great for the football stuff, but at twice the price. I have a 20D with the 17-85 EF-S and the 70-200mm f/4L and I am very please with both. Thanks Musty. > Have you considered the EF-S IS 17-85mm f/4-5.6 ? anothier piece of crap... avoid that lens at all cost ! Get the 17-40 L or the 24-70 L instead of the toy above > > Have you considered the EF-S IS 17-85mm f/4-5.6 ? > > anothier piece of crap... avoid that lens at all cost ! > > Get the 17-40 L or the 24-70 L instead of the toy above What an insightful analysis "piece of crap". Have you used the 17-85? There are quite a few users that have both the 17-40 L and the 17-85 and can attest that the 17-85 takes same quality as the L. Keep in mind that the 17-40L is an "affordable L" being in the $650 range. The EF-S being about $100 cheaper. What you get with the EF-S ofcourse is the much larger range and the IS - not to mention the size and weight, making it possibly the best walk-around lens for the 20D. Do you have any images to back up your claims? Like I said, there have quite a few posts on r.p.d from users who own both lenses and "piece of crap" is not what they are saying. I also own L-glass and can tell you that the 17-85mm is an excellent and versatile performer. Just another basher... Any posts from owners of the 17-85mm would be appreciated here. Even more important, any owners of both lenses (17-40 L and 17-85). >>>Have you considered the EF-S IS 17-85mm f/4-5.6 ? >> [quoted text clipped - 20 lines] > Any posts from owners of the 17-85mm would be appreciated here. Even more > important, any owners of both lenses (17-40 L and 17-85). I have both Canon lenses (17-85 and 17-40) in addition to the 28-135 and I'm very pleased with them. AFAIC, these are keeper lenses. The 17-85 lens is ideal with my 20D camera. I use the 17-40 and the 28-135 with my 1D MkII and I pleased with the results from using those lenses with 1D MkII camera. I intend getting the 24-70 F-28L and either the 70-200 F-4L or 70-200 F2.8L lens. I like the 70-200 F-2.8L lens but I also like the weight of the 70-200 F-4L lens. nick > >>>Have you considered the EF-S IS 17-85mm f/4-5.6 ? > >> [quoted text clipped - 30 lines] > > nick Thankyou for your post. Its good to hear from people that have actually experienced these lenses. I am happy with my 17-85, except that it is a little on the soft side at 17mm. Do you see the same phenomenon? How does you 17-40 f/4L compare at the wide end? Do you feel that the L is sharper? Regarding the 70-200 f/4L it is a very practical lens due to its weight. Also I have yet to read a negative or "average" review of that lens. I have read even some posts of users who sold their IS or f/2.8 versions and bough the f/4L instead just because of the weight and the images were just as good (obviously IS would help a lot, but price is quite high). Musty. >>>>>Have you considered the EF-S IS 17-85mm f/4-5.6 ? >>>> [quoted text clipped - 61 lines] > > Musty. I have 17-40/4L and 70-200/4L (and 300/4L IS). They are great but because they are slow, I have to crank up the ISO. I wish I had f/2.8 but I won't spend that kinds of money. > >>>>>Have you considered the EF-S IS 17-85mm f/4-5.6 ? > >>>> [quoted text clipped - 65 lines] > because they are slow, I have to crank up the ISO. I wish I had f/2.8 > but I won't spend that kinds of money. Are you shooting with 20D? I am finding that cranking up the ISO on 20D is no issue. Noise @ 1600 ISO is similar to other cameras at much lower ISO. For example ISO 800 is very good. Ofcourse f/2.8 will also give very shallow DOP for portraits and other isolation shots. >>>>>>>Have you considered the EF-S IS 17-85mm f/4-5.6 ? >>>>>> [quoted text clipped - 92 lines] > For example ISO 800 is very good. Ofcourse f/2.8 will also give very shallow > DOP for portraits and other isolation shots. I am waiting for a new 20D. I had used one for a week. I never tried anything about 800. Another thread stating 1600 is pushed, we shall see if it is proved. >I am waiting for a new 20D. I had used one for a week. I never tried >anything about 800. Another thread stating 1600 is pushed, we shall see >if it is proved. Others here have shown that 1600 (and 3200) are digital manipulations of 800, so if you shoot raw, there's no point in setting the ISO higher than 800. (Still, 800 is pretty high, especially when you consider how grainy most 800 ISO film is.) -Joel ---------------------------------------------------------------------------- Please feed the 35mm lens/digicam databases: http://www.exc.com/photography ---------------------------------------------------------------------------- >Others here have shown that 1600 (and 3200) are digital manipulations >of 800, Not exactly. I said that the Canon 10D, 300D, and 20D, when set to "1600", are actually internally amplifying for 800, and doubling the RAW values upon output. "3200" on the 10D and 20D is digitally manipulated 1600-level amplification. So what you get is this: ISO GAIN MULTIPLIER 100 1x 1x 200 2x 1x 400 4x 1x 800 8x 1x 1600 8x 2x 3200 16x 2x >so if you shoot raw, there's no point in setting the ISO >higher than 800. (Still, 800 is pretty high, especially when you >consider how grainy most 800 ISO film is.) If you shoot 1600, you might as well shoot at 800 with -1 exposure compensation, because you get an extra stop of headroom (of course, flash compensation needs to be equally offset, if flash is used). On the 10D (and possibly, the 300D as well, but I haven't really tested any 300D files), an additional benefit is that you avoid the ridiculous stripes of even numbers that have been offset by 1 to give some odd numbers in the data; perhaps to fool histograms. I have blurred dark frames at ISOs 1600 and 3200 from the 10D, and they show distinct zones of darker and lighter areas due to this striping when histogram-equalized. The 20D gives even RAW numbers throughout the image at ISOs 1600 and 3200. The amount of gain available at "ISO 3200" on these cameras can not be accomplished with the camera set to ISO 800, so "3200" is not as redundant and useless as "1600". In my experience, images shot at "3200" are cleaner looking than ISO 800 images under-exposed by 2 stops. IMO, Canon went too digital-minded in trying to create a smooth transition in image quality from one ISO to the next. Had they used pure amplifaction all the way through the range, image quality would have deteriorated very rapidly as you went to 1600 and 3200, so they limit the deterioration by using some math, but they could have done 11x amplification for ISO 1600, with 1.45x scaling instructions in the RAW data for the converters, and we would probably have an ISO 1600 worth using. Or, they could do that for the casual user, and have a custom function to turn on literal amplification for more technical users who see through the numbers. Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< > "leo" <someone@somewhere.net> wrote in message > > Ofcourse f/2.8 will also give very shallow > DOP for portraits and other isolation shots. Pardon my butting in with ignorant comments but I just realized that a fast lense (or ability to simulate with high ISO) gives both the ability to get narrow or deep DOF. Am I understanding this correctly? I'm still trying to grasp all the possibilities. > > "leo" <someone@somewhere.net> wrote in message > > [quoted text clipped - 6 lines] > > I'm still trying to grasp all the possibilities. Deep DOF uses small apertures (high f number), so this is correct. A fast lens has the advantage that it gives you shallower DOF due to larger apertures. Having a small aperture, is not any issue with most lenses I imagine (all you need is f/22). So in essence a "fast" lense provides a wider range of depth of field. Also keep in mind that DOF is a function of focal length so the smaller the focal length (eg 17mm vs 28mm) will give you larger DOF. >>>"leo" <someone@somewhere.net> wrote in message >>> [quoted text clipped - 14 lines] > focal length so the smaller the focal length (eg 17mm vs 28mm) will give you > larger DOF. OK so a telephoto lense limits your depth of field. So if I'm shooting macro, I would want a short lense right? But Telephoto enlarges things so it counteracts that benefit in terms of DOF. So if I used a wide angle lense (short?) that would mean I'd have to be be 1/2 inch from my flower but I could have decent depth of field vesus sitting 2 feet away with a telephoto lense. Am I getting the general idea? What goes into an ideal macro lense? > >>>"leo" <someone@somewhere.net> wrote in message > >>> [quoted text clipped - 23 lines] > > Am I getting the general idea? What goes into an ideal macro lense? I am not an expert on macro photography, but I dont believe you need a great DOF for macro shots. For example compare two scenarios: 1) Shooting a landscape where you want to capture maybe several miles of distance - here you will need massive DOF 2) Shooting a flower macro more where you want to have "acceptable" focus probably over an inch or two - This is not a large DOF, its a tiny DOF So generally macro shooting is done not with wide lenses (since you want to magnify and limit DOF). If you look at Canon EF lenses that are designated "macro" here are some examples: EF 180mm F3.5L macro EF 65mm F3.5L macro EF 100mm F2.8 macro EF 50mm f2.5 macro So you can see that focal length is not wide by any means (50 to 180mm). The main features of a macro lens would be as follows (I would think): - Long enough focal length to "magnify" the subject - Large aperture (small f) to limit DOF (you want to focus that one flower or insect) - Small focusing distance (eg the 50mm can focus as close as 23cm) which would give awesome magnification with 50mm focal length. Thanks Musty. >>>>> "leo" <someone@somewhere.net> wrote in message >>>>> [quoted text clipped - 53 lines] > - Small focusing distance (eg the 50mm can focus as close as 23cm) > which would give awesome magnification with 50mm focal length. At macro scales, lighting can be a major consideration: unless you are otherwise equipped, common solutions are more easily applied with larger lens-to-subject distances. SignatureFrank ess >>OK so a telephoto lense limits your depth of field. So if I'm shooting >>macro, I would want a short lense right? But Telephoto enlarges things [quoted text clipped - 13 lines] > 2) Shooting a flower macro more where you want to have "acceptable" focus > probably over an inch or two - This is not a large DOF, its a tiny DOF I'm not sure but the relative DOF issues are a problem with macro. Usually you end up only getting a 1/2-inch slice of focused flower in the middle. > So generally macro shooting is done not with wide lenses (since you want to > magnify and limit DOF). If you look at Canon EF lenses that are designated [quoted text clipped - 12 lines] > - Small focusing distance (eg the 50mm can focus as close as 23cm) which > would give awesome magnification with 50mm focal length. I don't understand what allows you to get close. > > Deep DOF uses small apertures (high f number), so this is correct. A fast > > lens has the advantage that it gives you shallower DOF due to larger [quoted text clipped - 12 lines] > > Am I getting the general idea? What goes into an ideal macro lense? Don't confuse telephoto/wide angle lenses with DOF characteristics. For a good explanation see - http://luminous-landscape.com/tutorials/dof2.shtml >>OK so a telephoto lense limits your depth of field. So if I'm shooting >>macro, I would want a short lense right? But Telephoto enlarges things [quoted text clipped - 7 lines] > Don't confuse telephoto/wide angle lenses with DOF characteristics. For a good > explanation see - http://luminous-landscape.com/tutorials/dof2.shtml Excellent explanation. However, under limited lighting, the wide angle should be able to use a smaller aperture (higher f-stop) and get better DOF. Or 'apparent DOF' I'm not sure because the distances & magnification are different. > Excellent explanation. However, under limited lighting, the wide angle > should be able to use a smaller aperture (higher f-stop) and get better > DOF. Why? If the lighting is the same, the exposure will be the same regardless of whether the lens is wide angle. SignatureJeremy | jeremy@exit109.com >>Excellent explanation. However, under limited lighting, the wide angle >>should be able to use a smaller aperture (higher f-stop) and get better >>DOF. > > Why? If the lighting is the same, the exposure will be the same regardless > of whether the lens is wide angle. OK so maybe I'm not understanding. I'm just thinking that wide angle has a larger piece of glass so it lets in more light but I don't know. > OK so maybe I'm not understanding. I'm just thinking that wide angle has > a larger piece of glass so it lets in more light but I don't know. It doesn't make a difference to your exposure settings; if you need a setting of 1/60 at f/8, you'll need that regardless of focal length. f/8 is a different size at different focal lengths, freeing you from needing to worry about adjusting your exposure according to focal length. SignatureJeremy | jeremy@exit109.com >>OK so maybe I'm not understanding. I'm just thinking that wide angle has >>a larger piece of glass so it lets in more light but I don't know. [quoted text clipped - 4 lines] > needing to worry about adjusting your exposure according to focal > length. Maybe we are talking about something different. If I zoom in from 28mm to 200mm & stand back to get the same frame, I need to lower the f-stop from 8 to 4.6 at the same speed (minimum to hand-hold), plus now I need an even faster speed since I've magnified the shake. Or since I'm talking about framing the same shot maybe it doesn't matter. I just tested & I think it makes a difference. I get to use a higher f10 at 28mm & therefore have more depth of field. I think. So for macros I'd do best with a shorter lense that allows me to get a few inches away from the subject than a telephoto lense a foot & a half away. Unless there is some other factor or I'm otherwise confused. >>>OK so maybe I'm not understanding. I'm just thinking that wide angle has >>>a larger piece of glass so it lets in more light but I don't know. [quoted text clipped - 8 lines] >to 200mm & stand back to get the same frame, I need to lower the f-stop >from 8 to 4.6 at the same speed . . . No you don't. If the object you're trying to photograph is correctly exposed at f/5.6 in the 200mm shot, it will be correctly exposed at f/5.6 in the 28mm shot. If you're using some form of center-weighted or multi-segment metering, though, it's quite possible that the extra field of view of the wide angle lens is getting more sky in the background (even if the foreground objects are framed correctly), and this can make the camera suggest f/8 for the aperture. Try using a spot meter (or an incident meter) instead of an averaging meter. > If the object you're trying to photograph is correctly > exposed at f/5.6 in the 200mm shot, it will be correctly exposed at f/5.6 > in the 28mm shot. True. However, if you use different lens systems, and one of them has _many_ more lenses than the other one, you may find _slight_ differences in brightness due to lens transmissivity. Assuming a 20 lens glass, with 0.5% loss at each glass-glass or glass-air border, you'll have 0.995^40 == 0.818 == 81.8% of the light left (i.e. about 1/3rd stop less) compared to an ideal lens. -Wolfgang >> If the object you're trying to photograph is correctly >> exposed at f/5.6 in the 200mm shot, it will be correctly exposed at f/5.6 [quoted text clipped - 9 lines] >glass-air border, you'll have 0.995^40 == 0.818 == 81.8% of the >light left (i.e. about 1/3rd stop less) compared to an ideal lens. If you're using lenses with that many elements, you'll probably have rather less than 0.5% loss at any surface. The most I've got in my personal selection is 18 elements in 16 groups, for a total of 34 surfaces. But some of those elements are coated, and I'd be surprised to find total losses as high as 15%. On the other end of the scale, I don't have any lenses with less than seven elements, although there is a lens I'd consider that only has five elements. So the difference is more likely to be at most 25 air-glass or glass-glass surfaces. I'd consider it astonishing if there was as much as one sixth of a stop difference, which is for all practical purposes almost undetectable. >>> If the object you're trying to photograph is correctly >>> exposed at f/5.6 in the 200mm shot, it will be correctly exposed at f/5.6 >>> in the 28mm shot. >>Assuming a 20 lens glass, with 0.5% loss at each glass-glass or >>glass-air border, you'll have 0.995^40 == 0.818 == 81.8% of the >>light left (i.e. about 1/3rd stop less) compared to an ideal lens. > If you're using lenses with that many elements, you'll probably > have rather less than 0.5% loss at any surface. Hopefully! But you also get loss with each mm of glass that the light has pass through. > The most I've > got in my personal selection is 18 elements in 16 groups, for a > total of 34 surfaces. 34? I must be dumb today ... I don't get that number. I counter with a few more elements. Lots of _heavy_ glass. Don't drop it! :-) > But some of those elements are coated, > and I'd be surprised to find total losses as high as 15%. We are talking about 1/100 loss of light on a lens -- I'd thought that quite realistic. > On the other end of the scale, I don't have any lenses with less > than seven elements, although there is a lens I'd consider that > only has five elements. So the difference is more likely to be > at most 25 air-glass or glass-glass surfaces. Just for kicks: Canon's EF 35mm f/2 has 5 elements, the EF 70-200 IS L USM has 23. (18 elements == 36 surfaces difference). If you go overboard, add a 1.4 and 2.0 converter (and better use a high-end body, if you want any autofocus at f/8), for 5 and 7 additional elements, for a 30 elements (60 surfaces) worst case difference. > I'd consider it > astonishing if there was as much as one sixth of a stop difference, > which is for all practical purposes almost undetectable. Canon seems to feel different, at least for TV cameras: http://www.canon-europe.com/TV-Products/News/CinePrimeReview.asp?ComponentID=342 23&SourcePageID=33108 | F-stop aperture marks are based on a theoretical mathematical | formula which when transferred to different lenses can | sometimes be inaccurate up to a full f-stop error. | This inaccuracy is actually much more likely with zoom | lenses as they have a more complex series of different glass | elements that move around inside to give the different focal | lengths. These glass elements can combine together to decrease | the actual transmission factor of the light passing through the | lens quite considerably at different focal lengths. http://www.medito.com/htdocs/dcforum/DCForumID64/6.html says about a lens: "also about 1/3 stop less transmission as is typical for zooms". Look at http://medfmt.8k.com/mf/fast.html (search for transmission) or http://medfmt.8k.com/third/primes.html for some more info. And here http://www.rugift.com/photocameras/mto_11_ca_lens_for_canon_eos.htm an actual transmission factor is listed as (no worse than) 0.77, aka loosing no more than 23% of the light (on an 1000mm f/10 *mirror* lens). That would be about 1/2 stop ... -Wolfgang >> The most I've >> got in my personal selection is 18 elements in 16 groups, for a >> total of 34 surfaces. > >34? I must be dumb today ... I don't get that number. Consider a very simple example; two elements in one group. That's 3 surfaces; one air/glass, one glass/glass, and one glass/air. >> I'd consider it >> astonishing if there was as much as one sixth of a stop difference, [quoted text clipped - 8 lines] >| the actual transmission factor of the light passing through the >| lens quite considerably at different focal lengths. Ah, but those Canon TV cameras have an astonishing zoom range; something around 100:1 It's not exactly surprising that at some part of that range some of the light doesn't manage to get through all the elements, but ends up in the sidewalls. (It's also hard to understand how surface-to-surface losses could be dependent on just where the element is in the path) >http://www.medito.com/htdocs/dcforum/DCForumID64/6.html >says about a lens: "also about 1/3 stop less transmission as is >typical for zooms". Again, that's not because of surface losses; it's because even those constant-aperture zooms sometimes manage to paint the inner walls of the lens barrel with some of the light that should really be passed on through the optical chain. >Look at http://medfmt.8k.com/mf/fast.html (search for >transmission) or http://medfmt.8k.com/third/primes.html >for some more info. Again, talking about light falloff in the corners; an artifact of the way the cross-section of the light beam is restricted by the geometry of the lens, especially at very wide apertures. >And here > http://www.rugift.com/photocameras/mto_11_ca_lens_for_canon_eos.htm >an actual transmission factor is listed as (no worse than) 0.77, >aka loosing no more than 23% of the light (on an 1000mm f/10 >*mirror* lens). That would be about 1/2 stop ... Hard to tell, but this too could be talking about the same issue. It's certainly not going to be talking about surface-to-surface transmission losses; this is, after all, a mirror "lens". My guess is that what it is talking about is really falloff; with no aperture control, you're always using the lens at full aperture. >>> The most I've >>> got in my personal selection is 18 elements in 16 groups, for a >>> total of 34 surfaces. >>34? I must be dumb today ... I don't get that number. > Consider a very simple example; two elements in one group. > That's 3 surfaces; one air/glass, one glass/glass, and one glass/air. I was dumb! Thank you. >>> I'd consider it >>> astonishing if there was as much as one sixth of a stop difference, >>> which is for all practical purposes almost undetectable. >>Canon seems to feel different, at least for TV cameras: >>| This inaccuracy is actually much more likely with zoom >>| lenses as they have a more complex series of different glass >>| elements that move around inside to give the different focal >>| lengths. These glass elements can combine together to decrease >>| the actual transmission factor of the light passing through the >>| lens quite considerably at different focal lengths. > Ah, but those Canon TV cameras have an astonishing zoom range; > something around 100:1 It's not exactly surprising that at > some part of that range some of the light doesn't manage to > get through all the elements, but ends up in the sidewalls. Well, that's true, but still > (It's also hard to understand how surface-to-surface losses > could be dependent on just where the element is in the path) element far away element close 1 element close 2 / / / ,-'/ // / ,-' | - | | ,-' ( / ( ,-( --------{ ---{ ---{ '-, ( \ ( '-( '-, | - | | '-,\ \\ \ \ \ \ element used to element used to element merely the corners the corners, moved closer path changed moderate acute very acute angle more obtuse angle angle at borders at corners of the than 'far away' element case Now, since you reflect more and more light as the angle gets more acute ... simply moving the element (and adjusting or not adjusting the light's path to that element) can easily change the amount of light passing through. Ok, it'll not change much in the central part or a lens ... >>http://www.medito.com/htdocs/dcforum/DCForumID64/6.html >>says about a lens: "also about 1/3 stop less transmission as is >>typical for zooms". > Again, that's not because of surface losses; it's because even > those constant-aperture zooms sometimes manage to paint the > inner walls of the lens barrel with some of the light that > should really be passed on through the optical chain. How would they paint the inner walls if not by refracting light that should have passed through, or by assuming their lenses are closer/larger than they are? >>And here >> http://www.rugift.com/photocameras/mto_11_ca_lens_for_canon_eos.htm >>an actual transmission factor is listed as (no worse than) 0.77, >>aka loosing no more than 23% of the light (on an 1000mm f/10 >>*mirror* lens). That would be about 1/2 stop ... > Hard to tell, but this too could be talking about the same issue. > It's certainly not going to be talking about surface-to-surface > transmission losses; this is, after all, a mirror "lens". Even mirror lenses may have glass lenses behind the mirror. (and some may be filled with glass instead of air --- no, don't ask me why, I'd assume someone thought that the glass-silver-air border reflects better than air-silver. Which may be true only for rather accute angles. > My > guess is that what it is talking about is really falloff; with > no aperture control, you're always using the lens at full aperture. My guess is that the mirror, not being perfect, does not reflect 100% of the light --- which leads to a somewhat darker image than you'd assume by the f-stop alone. -Wolfgang >> Again, that's not because of surface losses; it's because even >> those constant-aperture zooms sometimes manage to paint the [quoted text clipped - 4 lines] >light that should have passed through, or by assuming their >lenses are closer/larger than they are? Let's take a simple view of things. The light entering the front element has a circular cross-section, with an effective diameter depending on the aperture selected. That light continues on down the lens barrel. Light destined for the central part of the image continues on straight down the lens barrel. But light that will end up in the corners of the frame is entering at an angle. For wide apertures not all of the light beam from the front element falls on the next element (and the further away from the front element that next element is moved by the zoom mechanism, the less light actually hits it). > Maybe we are talking about something different. If I zoom in from 28mm > to 200mm & stand back to get the same frame, I need to lower the f-stop > from 8 to 4.6 at the same speed (minimum to hand-hold), You shouldn't, if it's the same scene, especially with the same framing. If the background is fooling the light meter in one version vs. the other (because the wide angle is getting more sky in there, for instance) then you may actually need to compensate for that. > Or since I'm talking about framing the same shot maybe it doesn't > matter. I just tested & I think it makes a difference. I get to use a > higher f10 at 28mm & therefore have more depth of field. I think. Don't trust the meter... it lies. It's probably changing the recommended exposure due to different light in the background. At wide angle it may be drastically underexposing the shot due to backlight. SignatureJeremy | jeremy@exit109.com > >>OK so maybe I'm not understanding. I'm just thinking that wide angle has > >>a larger piece of glass so it lets in more light but I don't know. [quoted text clipped - 17 lines] > few inches away from the subject than a telephoto lense a foot & a half > away. Unless there is some other factor or I'm otherwise confused. That is not always practical. For example an insect might get scared and fly or run off if you are too close, so a more tele-style macro lens is handy when getting close to the subject may not be possible or practical (eg a dangerous scorpion). This is why Canon offers both a wider (but not "wide") and tele macro lenses. Even if you can get REALLY close, nothing beats a bit of tele to get very detailed close ups. Consider those insect photographs where they take the shot of just the eye. >>>Excellent explanation. However, under limited lighting, the wide angle >>>should be able to use a smaller aperture (higher f-stop) and get better [quoted text clipped - 5 lines] >OK so maybe I'm not understanding. I'm just thinking that wide angle has >a larger piece of glass so it lets in more light but I don't know. This is also generally true, but the consequences of this optical fact are that telephotos lenses tend to be slower, while wide-angle lenses tend to be faster. An f/3.5 300mm lens is expensive, while an f/3.5 28mm lens is cheap. As for idential f-stops at different focal lengths, see my last post. -Joel ---------------------------------------------------------------------------- Please feed the 35mm lens/digicam databases: http://www.exc.com/photography ---------------------------------------------------------------------------- >This is also generally true, but the consequences of this optical fact >are that telephotos lenses tend to be slower, while wide-angle lenses >tend to be faster. An f/3.5 300mm lens is expensive, while an f/3.5 >28mm lens is cheap. That's only moderately wide, though. When you start going wider than that, the lenses start getting slower again, at a given price point. Most of the affordable fast lenses you see are in the 50 to 100 mm range. Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< >>>>Excellent explanation. However, under limited lighting, the wide angle >>>>should be able to use a smaller aperture (higher f-stop) and get better [quoted text clipped - 10 lines] >tend to be faster. An f/3.5 300mm lens is expensive, while an f/3.5 >28mm lens is cheap. Is this a roughly-right way of looking at it: The aperture of a 28mm f/1.0 lens will be 28mm. The aperture of a 300mm f/10 lens will be 30mm. Therefore, in some crude way, the amount of glass (and therefore, roughly, the cost) will be comparable. The aperture of a 300mm f/2.8 lens will be about 100mm and will therefore need pieces of glass at least three times the diameter of the two examples above. This would be _at least_ 9x the cost (the area is squared), probably more because the lens elements will be thicker, and probably need better machining. Regards, Graham Holden (g-holden AT dircon DOT co DOT uk) -- There are 10 types of people in the world; those that understand binary and those that don't. > Is this a roughly-right way of looking at it: > [quoted text clipped - 10 lines] > probably more because the lens elements will be thicker, and probably need > better machining. I won't research prices to see the correlation, but that is roughly right. Further, of course, is the volume effect. As the prices of these longer/faster lenses go up, there is less market, less volume so the price is pushed up even further. A Canon 1200mm f/5.6 is over $118,000. I believe you can negotiate a price break if you order 3 or more. Signature-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: there's no such thing as a FreeLunch. >> Excellent explanation. However, under limited lighting, the wide angle >> should be able to use a smaller aperture (higher f-stop) and get better >> DOF. > >Why? If the lighting is the same, the exposure will be the same regardless >of whether the lens is wide angle. Without a tripod, you can get sharper shots under the same lighting conditions with wider lenses. To consider an extereme example, at f/30, a 300mm lens will give you nothing but blur hand-held, while a 35mm lens will give most people a crystal clear shot. -Joel ---------------------------------------------------------------------------- Please feed the 35mm lens/digicam databases: http://www.exc.com/photography ---------------------------------------------------------------------------- >Pardon my butting in with ignorant comments but I just realized that a >fast lense (or ability to simulate with high ISO) gives both the ability >to get narrow or deep DOF. Am I understanding this correctly? Only a fast lens. The wider the aperture (that is, the small the number), the less DOF you get. Changing the ISO doesn't change the DOF. -Joel ---------------------------------------------------------------------------- Please feed the 35mm lens/digicam databases: http://www.exc.com/photography ---------------------------------------------------------------------------- >>>>>Have you considered the EF-S IS 17-85mm f/4-5.6 ? >>>> [quoted text clipped - 53 lines] > little on the soft side at 17mm. Do you see the same phenomenon? How does > you 17-40 f/4L compare at the wide end? Do you feel that the L is sharper? Musty, don't be too concerned about the 17-85 lens seemingly being a little on the soft side at 17mm. The lens is a very good lens. I do my own computer processing and I have yet to find a problem with the use of this lens. I had the 17-40MM F4L lens before I bought the 17-85 lens IS lens and yet I still bought the 17-85mm lens and I'm quite happy having both lenses. > Regarding the 70-200 f/4L it is a very practical lens due to its weight. > Also I have yet to read a negative or "average" review of that lens. I have > read even some posts of users who sold their IS or f/2.8 versions and bough > the f/4L instead just because of the weight and the images were just as good > (obviously IS would help a lot, but price is quite high). When I bought my 1D MkII, I used both the 16-35 F2.8L and the 17-40 F4L lenses and I found the 17-40 F4L lens to be better than the 16-35 F2.8L lens. I did not like the noticeable distortion of the 16-35mm F2.8L lens at 16mm. I had reservations about not getting a fast lens because I have always bought fast lenses but the 17-40mm F4L is a super lens and I no longer have any reservations about the lens not being a fast lens. nick > Musty. At least I own the 17-85mm lens and think it is excellent. both the 17-85 and the 17-40 suffer from CA wide open at 17mm but the 17-85mm is sharp, focuses fast, even in dim light, and the IS works brilliantly. What I also like is that it is a great walkaround lens -- nice and compact. Larry > > Have you considered the EF-S IS 17-85mm f/4-5.6 ? > > anothier piece of crap... avoid that lens at all cost ! > > Get the 17-40 L or the 24-70 L instead of the toy above >> Have you considered the EF-S IS 17-85mm f/4-5.6 ? > > anothier piece of crap... avoid that lens at all cost ! > > Get the 17-40 L or the 24-70 L instead of the toy above Seems folks all think that the "L" means the lens has to be sharper. That's not what Canon has said. "L" means that the lens has "exotic" (read: recently developed) technology. The 50mm f1.4 is not an L lens, and from what I've heard, they don't get much sharper than that. Will D. >The 50mm f1.4 is not an L lens, and from what I've heard, they don't get >much sharper than that. That's a myth. There are much sharper lenses than it, though it is sufficient in many cases. Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< >>The 50mm f1.4 is not an L lens, and from what I've heard, they don't get >>much sharper than that. > > That's a myth. There are much sharper lenses than it, though it is > sufficient in many cases. Please: What Canon lenses are much sharper, or even just sharper? SignatureJohn McWilliams >>>The 50mm f1.4 is not an L lens, and from what I've heard, they don't get >>>much sharper than that. [quoted text clipped - 3 lines] > >Please: What Canon lenses are much sharper, or even just sharper? The 500mm f4L IS, 300mm f4L IS, 300mm f2.8L IS, 400mm f2.8L IS, 70-200mm f2.8L IS ... Tamron macros are sharper, the Sigmna 50mm f2.8 EX Macro is sharper ... Look at Caonon's MTF chart! It only approaches one for low-contrast, stopped down only: http://consumer.usa.canon.com/ir/controller?act=ModelDetailAct&fcategoryid=152&m odelid=7307 Some of the lenses I mentioned hug the 1 for all lines! Signature<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS@no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< Is it possible to directly compare sharpness of lenses at very different focal lengths - to say that this 500mm lens is sharper than some other 50mm lens? I understand that MTF charts can be produced for any lens and give a numeric comparison, but it doesn't seem that meaningful since you could not normally photograph the same object with the two very different lenses. If (for example) a given 300mm lens gets better MTF scores than a given 35mm lens, does that mean that in practice if you photographed the same subject with both lenses, moving much closer to the subject with the 35mm lens and a long distance away with the long lens, then the lens with better MTF score would usually give a sharper picture? SignatureEd Avis <ed@membled.com > Is it possible to directly compare sharpness of lenses at very > different focal lengths - to say that this 500mm lens is sharper [quoted text clipped - 3 lines] > meaningful since you could not normally photograph the same object > with the two very different lenses. That's correct. Producing an MTF for each lens is not the most difficult thing, but eliminating camera shake is much more of an issue with the 500mm. Also the perspective will be different if you attempt to frame the same subject in a similar fashion. > If (for example) a given 300mm lens gets better MTF scores than a > given 35mm lens, does that mean that in practice if you photographed > the same subject with both lenses, moving much closer to the subject > with the 35mm lens and a long distance away with the long lens, then > the lens with better MTF score would usually give a sharper picture? Probably yes, depending on output size and assuming perfect camera technique, but again perspective will be different because of the changed shooting position. A sharper picture can mean more than the ability to visually resolve fine detail though. Higher contrast of spatial frequencies that are important for the impression of sharpness is also important. Bart > Santa was very good and brought a 20D. Now the next challenge is what > lenses to buy? My subjects will be the family holiday pictures and this > years Rose Parade and Rose Bowl Game (50 yard line seats!). I am so enjoy > Yosemite type scenery. > > Any ideas and suggestions would be appreciated. A lens I use on both a 10D and a 20D is the Canon 28-135 IS. While some of you dislike it, it gives me generally excellent performance. Any faults can be easily adjusted for in Photoshop (now using CS). And its price is excellent. However, for a wider-angle lens, you may want to consider one of the zooms starting at 17mm (or thereabouts); the Canon 17-40mm gets very high marks, and there are also much cheaper non-Canon zooms in that range. Take a look at the reviews on http://www.fredmiranda.com for more info. Bill P > Santa was very good and brought a 20D. Now the next challenge is what > lenses to buy? My subjects will be the family holiday pictures and this > years Rose Parade and Rose Bowl Game (50 yard line seats!). I am so enjoy > Yosemite type scenery. > > Any ideas and suggestions would be appreciated. A lens I use on both a 10D and a 20D is the Canon 28-135 IS. While some of you dislike it, it gives me generally excellent performance. Any faults can be easily adjusted for in Photoshop (now using CS). And its price is excellent. However, for a wider-angle lens, you may want to consider one of the zooms starting at 17mm (or thereabouts); the Canon 17-40mm gets very high marks, and there are also much cheaper non-Canon zooms in that range. Take a look at the reviews on http://www.fredmiranda.com for more info. Bill P > > Santa was very good and brought a 20D. Now the next challenge is what > > lenses to buy? My subjects will be the family holiday pictures and this > > years Rose Parade and Rose Bowl Game (50 yard line seats!). I am so enjoy > > Yosemite type scenery. > > > > Any ideas and suggestions would be appreciated. An interesting observation I'll share with you is the way this group is fanatically Canon biased. Canon make some pretty awful lenses. They make a lot of pretty good ones too but when someone tells you about one of the awful lenses, everyone seems to give out a flood of "you don't know what you are talking about" disciple jargon. Sigma make a lot of bloody awful lenses but they make some pretty good ones too. Whenever someone recommends one of the better Sigma lenses which incidentally are as good optically as the corresponding Canon lens, the disciples start with their flood of "you don't know what you are talking about" posts. So let me give you some 'good' advise. Unless you intend to spend big bucks, stay away from an "IS" lens. The cheaper ones from Canon are so slow that to focus on a scratching dog, he will have time to get up and leave the room before the lenses can go from 300 mm infinity to their close range! If price is a prime consideration you will go a long way before faulting the Sigma EX, DG range of lenses with Canon mounts. One in particular that stands out is the 24~70 f2.8 DG, DF lens. This is 1/3 rd the price of the Canon version and apart from a slower focus motor and the occasional inability to grab focus on low contrast, low light subjects, is optically close to equal to the Canon lens. The Canon 17~55 plastic lens which comes with the 20D kit is a pretty good all-round lens for most people. It is sharp and relatively free of flair. At the price it is a rare bargain. Pity it only fits a D300 or D20 but I guess that's the price of digital only lenses. This would suit your scenery photography in all but the most demanding situations. Use it between 20mm and 45mm and never stop down past f11 for the best results. If you need reach (and you will for football games) you really have no alternative but to spend money. The 100~300 f4 Sigma is no match for Canon's lens. Pity about the cost but sometimes you have to cough up or go without. Stay right away from monster range zoom lenses. Lenses like 28~300 are no value at all when at some point of their range they are poor... That'll be the range you need! Good luck, Doug > An interesting observation I'll share with you is the way this group > is fanatically Canon biased. Canon make some pretty awful lenses. They [quoted text clipped - 13 lines] > and leave the room before the lenses can go from 300 mm infinity to > their close range! I am sorry but you don't know what you are talking about! I use the 28-135 IS lens all the time on my 10D and I have found it to be quite fast at AF even in fairly low light. Unlike the 75-300 IS (which is really quite poor), the 28-135 IS has the ring-type USM with full-time manual focus. The sharpness and contrast won't equal what you get on a good 'L' zoom, but the price doesn't match either. Of course it is possible that you may have experience of a 'bad' 28-135 IS that had a serious problem with its AF. SignatureMark Heyes (New Zealand) See my pics at www.gigatech.co.nz (last updated 12-Nov-04) "There are 10 types of people, those that understand binary and those that don't" > Of course it is possible that you may have experience of a 'bad' 28-135 IS > that had a serious problem with its AF. It seems more and more to me that for any given lens that costs less than $1000, you will find at least one person who has had a terrible experience with it. : ) steve > I am sorry but you don't know what you are talking about! I use the See? What did I tell you? Always a deciple of EOS prepared to sacrifice their credibility and jump to Canon's defence. I never even mentioned that lens but he sure as hell knew which one I included in my assessment! Good onya, Mark >> I am sorry but you don't know what you are talking about! I use the >> [quoted text clipped - 7 lines] > Good onya, > Mark Doug, you said "stay away from an IS lens," which would imply any IS lens, since you didn't mention a particular one. The 28-135 that I have focuses fast, as fast as the 18-55 kit lens or the 100-300 that my wife has. Yes, the 75-300 is slow, and so is the 100-400 IS, if you don't use the focus limiter, but the latter is moving a lot of mass, internally. SignatureSkip Middleton http://www.shadowcatcherimagery.com >> I am sorry but you don't know what you are talking about! I use the >> > See? What did I tell you? > Always a deciple of EOS prepared to sacrifice their credibility and > jump to Canon's defence. I was not jumping to Canon's defence, I was defending a lens that I like and use that definitely does not behave in the way you suggested. Just because you bought a lens with some weird slow focus problem does not mean that everyone should avoid that lens. > I never even mentioned that lens but he sure as hell knew which one I > included in my assessment! You never mentioned that lens? You replied to someone mentioning that lens to say that people should avoid Canon's sub-$1000 lenses. If you were not referring to that lens then why did you throw your opinion in reply to someone recommending the 28-135 IS? I find it interesting that you only quoted my tongue in cheek statement (you said that when criticizing Canon people would reply saying you don't know what you are talking about, so I opened with that statement), but you snipped out the part of my post where I gave my opinion based on my real- world experience with this particular lens. SignatureMark Heyes (New Zealand) See my pics at www.gigatech.co.nz (last updated 12-Nov-04) "There are 10 types of people, those that understand binary and those that don't" > See? What did I tell you? > Always a deciple of EOS prepared to sacrifice their credibility and jump to > Canon's defence. > I never even mentioned that lens but he sure as hell knew which one I > included in my assessment! Shut up and go play with your Sigmas. Before you go Sigma http://www.tawbaware.com/sigma_tokina_test1.htm > > > Santa was very good and brought a 20D. Now the next challenge is what > > > lenses to buy? My subjects will be the family holiday pictures and this [quoted text clipped - 44 lines] > Good luck, > Doug > Before you go Sigma > http://www.tawbaware.com/sigma_tokina_test1.htm The only problem with ad-hoc tests like this is that there is no mention of a mechanical check of the lenses before photographs. It is quite possible that the Sigma lens has a back focus issue and the Tokina in the test does not. My own personal tests proved exactly the opposite to the results in this test. Otherwise I would be using Tokina instead of Sigma. The difference is I had the 20D camera calibrated for back focus when I bought it. I had the Sigma lens calibrated to suit the camera when I bought it. The Tokina? I just opend the box and shot 20 frames. All of them out of focus. Same deal with a Canon 50mm f1.8. Just put 'em back on the shelf and don't buy. The interesting part of this is that the camera was forward focusing with a 50mm f1.4 lens and that is the one it was calibrated for so the camera, was correctly focusing before I put any other lenses on it. Maybe ever 4th or 5th Sigam 'EX' series lens will not focus as well as a USM Canon lens out of the box but for a small fee $75 or so, you can have the lens calibrated to match the camera and get the same or better focus results as with a Canon lens. Do the math and you'll see that (aussie dollars) $942.08 plus $75 for calibration is a long way short of $2497.35 for a Canon lens. Tokina's will benefit from the same calibration too. In fact every camera and lens (USM and L series included) should be calibrated after purchase or you may be asking yourself for a long, long time, why your photos are not as sharp as other people's. Doug >> Before you go Sigma >> http://www.tawbaware.com/sigma_tokina_test1.htm [quoted text clipped - 6 lines] > difference is I had the 20D camera calibrated for back focus when I bought > it. Calibrated for back focus/front focus? So what do I do when I use both types? Do I send the body into the camera shop to be recalibrated every time I change lenses? > I had the Sigma lens calibrated to suit the camera when I bought it. The > Tokina? I just opend the box and shot 20 frames. All of them out of focus. > Same deal with a Canon 50mm f1.8. Just put 'em back on the shelf and don't > buy. The interesting part of this is that the camera was forward focusing > with a 50mm f1.4 lens and that is the one it was calibrated for so the > camera, was correctly focusing before I put any other lenses on it. Oh, you're saying that it's the lens that has to be calibrated? > Maybe ever 4th or 5th Sigam 'EX' series lens will not focus as well as a USM > Canon lens out of the box but for a small fee $75 or so, you can have the > lens calibrated to match the camera and get the same or better focus results > as with a Canon lens. Do the math and you'll see that (aussie dollars) > $942.08 plus $75 for calibration is a long way short of $2497.35 for a > Canon lens. Do they do this as you wait, or is this one of those "We'll put it in the shop, and it'll have to wait its turn..." deals? > Tokina's will benefit from the same calibration too. In fact every camera > and lens (USM and L series included) should be calibrated after purchase or > you may be asking yourself for a long, long time, why your photos are not as > sharp as other people's. > > Doug I've never heard of this sort of thing, actually. Your post suggests that this is common knowledge. I'm right willing to admit there's much I don't know so I'm ready to learn something new. Will you point me towards what I've been missing all this time? Thanks, Will D. > I've never heard of this sort of thing, actually. Your post suggests > that this is common knowledge. I'm right willing to admit there's much [quoted text clipped - 4 lines] > > Will D. No idea whether you are baiting me or not but... Background: All production SLR cameras need some pretty tightly controlled lens rear element to film plane dimensions to produce exactly what you see in the viewfinder, focus wise. Also the lens rear element to mirror to penta prism relationship is critical to focus too although not so much with auto focus. The distance between the film plane and the rear lens element is know as the "back focus". Presumably the lens focus would then be the 'front focus'? Auto focus lenses can be adjusted for where they focus within their depth of field. This I'll call "calibration of the focus point". Large format and other bellows focusing cameras use the back focus exclusively and don't suffer from back focus errors. I first discovered this relationship after buying an Olympus camera in the '80s. A 600 mm lens I'd sold my car to buy wouldn't take a sharp picture on this camera. The Oly service centre put thin shims between the lens mount and the body to correct the problem. They had a test lens specifically for this problem. After that they adjusted the penta prism to match the new back focus distance and I went on to take some of the best wild life pictures of my life with that combination. Now... When I buy a new body, the first thing I do is get the back focus checked before ever taking a picture. My 10D was focusing behind the focus point, out of the box. The 20D was forward focusing - out of the box. The technician I use charg |
Enable EMail Alerts
Start New Thread
Reply to this Message