 |
 | 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 / February 2005Difference in bokeh quality - same lens
Tamron 24-135mm lens Annoying bokeh (ISO 100, 69mm focal, 1/640, f/5): http://homepage.mac.com/getosx/kimmie/bee.jpg Decent bokeh (ISO 100, 135mm focal, 1/400, f/6.3): http://homepage.mac.com/getosx/kimmie/ladybug2.jpg Is the difference because of the background subject matter (mostly linear in the decent one)? Or because of the difference in focal length or shutter speed or slight difference in aperature? Or something else entirely? Any input is appreciated. Thanks, Greg  Signature"tilt the bottle, f.ck the cup, yeah" - Bottom 12 Not a bokeh expert, but.. Yes, the nature of the background (contrasts/shapes) certainly can affect the look of 'bokeh', even if it doesn't change the actual bokeh itself. And of course the relative distance to the background will also affect it, by changing how far out of focus it is. And yes, a difference in zoom angle, or setting the lens into macro mode (which for this lens probably involves moving internal elements) could certainly affect it, and the aperture (and particularly the shape of the aperture openeing at that setting) will affect it as well. I don't see how shutter speed could make a difference, unless the background was moving...! In the examples you posted, it seems to me that the main difference is that the background in the `nice` one (lovely shot by the way) is much more out of focus - in fact if you look at the one stalk of wheat (?) on the right that is much closer, it is beginning to show the same `bad` bokeh... I might add, I've seen MUCH worse! OT: Yeah that's wheat and it is beautiful. > Not a bokeh expert, but.. > [quoted text clipped - 15 lines] > on the right that is much closer, it is beginning to show the same > `bad` bokeh... I might add, I've seen MUCH worse! > Tamron 24-135mm lens > [quoted text clipped - 9 lines] > > Any input is appreciated. The greater contrast in the first image highlights the donut shape of the bokeh. You can especially see it in the white dots to the left. There's also the compositional problem of the stem that pokes into focus over the flower. It feels like it's poking you in the forehead. :-) The second image doesn't have as much contrast in the background, so the bokeh appears more even. If you look at the two highlighted leaves in the bottom right, you can see the distinct edges of the blur, but that's only because they're highlighted against a dark background. The rest of that individual plant is suitably blurred, given the lack of contrast. Nice pic. :-) > > Tamron 24-135mm lens > > [quoted text clipped - 12 lines] > The greater contrast in the first image highlights the donut shape of > the bokeh. You can especially see it in the white dots to the left. Excellent, that explains it well. > There's also the compositional problem of the stem that pokes into focus > over the flower. It feels like it's poking you in the forehead. :-) Hahaha, yeah, I printed a version with that cropped out. When I added a little more contrast that stem definitely looked like it was going to poke an eye out. > The second image doesn't have as much contrast in the background, so the > bokeh appears more even. If you look at the two highlighted leaves in > the bottom right, you can see the distinct edges of the blur, but that's > only because they're highlighted against a dark background. The rest of > that individual plant is suitably blurred, given the lack of contrast. > Nice pic. :-) Thanks. Other than the Tamron having an extremely stiff zoom ring I'm pretty happy with it. This is another ladybug shot using it on my 300D: http://homepage.mac.com/getosx/kimmie/ladybug1.jpg Greg Signature"destroy your safe and happy lives before it is too late, the battles we fought were long and hard, just not to be consumed by rock n' roll" - the mekons > This is another ladybug shot using it on my 300D: > http://homepage.mac.com/getosx/kimmie/ladybug1.jpg > > Greg > -- Good macro shot, but I am more interested in your hand, specifically that your third finger is considerably longer than the first. This appears to be an unusual occurrence, as I also have the same longer third finger, but I can find few other people with the same characteristic. Almost everyone's third finger is shorter than their first. (My first finger is my trigger finger on my 300D, just to stay on topic {:-) Colin. > > This is another ladybug shot using it on my 300D: > > http://homepage.mac.com/getosx/kimmie/ladybug1.jpg [quoted text clipped - 6 lines] > third finger, but I can find few other people with the same > characteristic. Very interesting, I had never heard that before. My toes are interesting lengths, too. Greg >> > This is another ladybug shot using it on my 300D: >> > http://homepage.mac.com/getosx/kimmie/ladybug1.jpg [quoted text clipped - 11 lines] > > Greg That's because you're an alien freak! SignatureSlack > >> > This is another ladybug shot using it on my 300D: > >> > http://homepage.mac.com/getosx/kimmie/ladybug1.jpg [quoted text clipped - 13 lines] > > > That's because you're an alien freak! Shhhhh. Please do not disseminate that information. Greg >>This is another ladybug shot using it on my 300D: >>http://homepage.mac.com/getosx/kimmie/ladybug1.jpg [quoted text clipped - 7 lines] > third finger, but I can find few other people with the same > characteristic. My 3rd f. is longer than my 1st by about 5 and 10mm (left/right resp.). The shot above is -not- macro. Cheers, Alan 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. > >>This is another ladybug shot using it on my 300D: > >>http://homepage.mac.com/getosx/kimmie/ladybug1.jpg [quoted text clipped - 11 lines] > > The shot above is -not- macro. You're right, it's not. But as pretty much a beginner what makes a macro shot a macro shot? The Tamron 24-135 says it's a macro lens, it focuses as close as 16" and the mag ratio is 1:3.3. I didn't buy it as a macro lens so it doesn't matter to me. I also have the Canon 100 2.8 macro which I didn't have along on the above outing. Greg I think true macro reproduction is meant to be 1:1 or greater! But lens manufacturers seem to have hijacked the term and applied it to any lens that can focus closer than about 12"... (O; > I think true macro reproduction is meant to be 1:1 or greater! But > lens manufacturers seem to have hijacked the term and applied it to any > lens that can focus closer than about 12"... (O; Yep. Real macros are 1:1 or better and not zoom. 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. > > I think true macro reproduction is meant to be 1:1 or greater! But > > lens manufacturers seem to have hijacked the term and applied it to any > > lens that can focus closer than about 12"... (O; > > Yep. Real macros are 1:1 or better and not zoom. As a beginner I'm not getting my head around the 1:1 ratio. What is being compared there? Thanks, Greg Signature"destroy your safe and happy lives before it is too late, the battles we fought were long and hard, just not to be consumed by rock n' roll" - the mekons >>>I think true macro reproduction is meant to be 1:1 or greater! But >>>lens manufacturers seem to have hijacked the term and applied it to any [quoted text clipped - 4 lines] > As a beginner I'm not getting my head around the 1:1 ratio. What is being > compared there? Very simply put, the image on the sensor is the exact same size as the subject. For example, if you photograph an insect that is 10mm long at the closest focus distance it will form an image 10mm long on the sensor (or film). This is a 1:1 magnification ratio. For a Canon 20D, that would be about 1560 pixels, or a print of the 10mm insect of over 5 inches (at 300 dpi). SLR Macro lenses are typicaly fixed focal lenghts of 50, 100 (90, 100, 105) mm and a few longer FL's (such as the Sigma 180 macro). The only "true macro" zoom that I know of is the Minolta 50mm 3:1 f/1.7-2.8 power zoom macro lens. In this case you get true mag up to 3 times (which doesn't sound like much until you see the photos blown up on a slide projector...). But this lens demands a lot of patience to learn to use effectively. Not to be confused with zoom ratio (eg: where a camera manuf says this is a 3x lens meaning the focal lenght ratio is 3:1 (eg: a 100-300mm lens has a 3:1 zoom ratio, or "3x power" although)). Hope that helps. Cheers, Alan. 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. > >>>I think true macro reproduction is meant to be 1:1 or greater! But > >>>lens manufacturers seem to have hijacked the term and applied it to any [quoted text clipped - 10 lines] > distance it will form an image 10mm long on the sensor (or film). This is a 1:1 > magnification ratio. Got it, thanks. > For a Canon 20D, that would be about 1560 pixels, or a print of the 10mm insect > of over 5 inches (at 300 dpi). > > SLR Macro lenses are typicaly fixed focal lenghts of 50, 100 (90, 100, 105) mm > and a few longer FL's (such as the Sigma 180 macro). Yep, I have the Canon EF100. One last question on this: how does the 1.6x conversion of my Rebel effect the 1:1 ratio? I understand that it will be 1:1 on the sensor. I guess I could do the numbers like you've done with 20D. Thanks again, Greg >>>As a beginner I'm not getting my head around the 1:1 ratio. What is > [quoted text clipped - 35 lines] > the 1:1 ratio? I understand that it will be 1:1 on the sensor. I guess I > could do the numbers like you've done with 20D. Again, it doesn't affect the image on the film plane at all. Just that the overall image is cropped around the edges. For DRebel, just look up the sensor width in pixels and mm and do the math. Cheers, alan 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. <snip> > This is another ladybug shot using it on my 300D: > http://homepage.mac.com/getosx/kimmie/ladybug1.jpg I guess you know that this excellent lens has compromised your personal information: fingerprint! SignatureFrank ess My fingerprint? I don't think so. That's a fake. Pretty good, huh? |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.