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Photo Forum / General Photo Topics / General Topics / October 2005telephoto lens
Hi All, I need to be able to read aircraft registration numbers from one quarter mile away. These numbers are about 5" or so tall. What size telephoto lens will do this? What brand of lenses represents the best value (performance/price) today? Thx. Terry > Hi All, > [quoted text clipped - 6 lines] > > Terry To what are you going to attach this lens? Do you care about quality of the image or do you just want to read the numbers. Are the aircraft moving or sitting still? What are the lighting conditions? And for what purpose? (Curios to know what you are up to) A large prime tele with IS (Image stabilization) is gonna set you back allot of $$ Cheap long teles are available but offer very little in the way of quality images. > To what are you going to attach this lens? > [quoted text clipped - 12 lines] > Cheap long teles are available but offer very little in the way of quality > images. I'll need to pickup a SLR digital that accepts 35 mm lenses. My 717 Sony will only accept a proprietary 2X ....and that's not gonna cut it. I just want to read the numbers on the pic. The aircraft are slow moving, usually less than 100 mph I think. The pics will be taken in broad daylight - good natural light. Any recommendations really appreciated.... Well, you can get to 1200mm with a Canon 600mm f/4 IS USM and a 2X. Get a large megapixle camera so you can crop in another 2x and maybe still read the numbers. This is gonna cost ya though. 1/4 mile aint that far but 5 inch letters and a moving target at that distance makes me think that any motion blur or focus issues are gonna jeopardize the legibility of the numbers. EOS-1Ds Mark II Camera would give you 16.7Mega Pixels to work with plus a 1.3X conversion factor on the lens gets you to 1500mm with a 2x crop in Photoshop and you equivalent to 3000mm. You would have a great setup for birding or sports photography.. This is not the cheap rout and there may be a better way. I will yield the floor to other opinions >> Hi All, >> [quoted text clipped - 23 lines] > Cheap long teles are available but offer very little in the way of quality > images. > Well, you can get to 1200mm with a Canon 600mm f/4 IS USM and a 2X. Get a > large megapixle camera so you can crop in another 2x and maybe still read [quoted text clipped - 13 lines] > > I will yield the floor to other opinions 1200mm seems like more then what is needed, that would yeild a image of close to .4mm in the image plan. Assuming a crop factor of 1.6 this would be about 1.7% of the frame, for a 3000 pixel wide image that is a letter that is 51 pixels high. It only take about 10 pixel high letter to be very readable. Scott > >> Hi All, > >> [quoted text clipped - 23 lines] > > Cheap long teles are available but offer very little in the way of quality > > images. I agree it might be difficult keeping the letters in the viewfinder. I went all out, I like having headroom. A long zoom might be an alternative. $$$? >> Well, you can get to 1200mm with a Canon 600mm f/4 IS USM and a 2X. Get >> a [quoted text clipped - 56 lines] >> > quality >> > images. >I need to be able to read aircraft registration numbers from one quarter >mile away. Yoiks. I'd slap a t-ring adapter onto a high-power telescope for that. >I need to be able to read aircraft registration numbers from one quarter mile away. I just heard about a guy who attached a 1200mm L lens to an XLR HD video camera (has an EF adapter) and put a 2x converter on it. after the 7x crop factor of the HD camera, he apparently ended up with 16,200mm total effective focal length. That'll do, yes? > Hi All, > [quoted text clipped - 6 lines] > > Terry It will depend somewhat on the camera but you will need something like a 250mm lens. See how far away you can read a 5 inch letter using a shorter lens then scale from there. If for example you can read the letters from a photo taken at 200 ft using a 50mm lens then you would need a lens 5280 / (4 * 400) * 50mm or a 330mm lens to get the same size letters in the photo at 1/4 mile Scott >> Hi All, >> [quoted text clipped - 15 lines] > * 400) * 50mm or a 330mm lens to get the same size letters in the photo > at 1/4 mile The amount of blur caused by dust in the air and whatnot might be significant to this calculation.  SignatureMåns Rullgård mru@inprovide.com Per M?ns Rullg?rd: >The amount of blur caused by dust in the air and whatnot might be >significant to this calculation. What about camera movement? Wouldn't he need an IS lens or a tripod? SignaturePeteCresswell > Per M?ns Rullg?rd: > >The amount of blur caused by dust in the air and whatnot might be [quoted text clipped - 3 lines] > -- > PeteCresswell The fact is that 1/4 mile is pretty close, this should be a pretty easy shot. I 300mm lens would be a good choice, this is easily hand held under most lighting conditions. Scott Are you sure? 5" lettering at 3.75 city blocks and you gota make out each number. >> Per M?ns Rullg?rd: >> >The amount of blur caused by dust in the air and whatnot might be [quoted text clipped - 9 lines] > > Scott Per Scott W: >The fact is that 1/4 mile is pretty close, this should be a pretty easy >shot. I 300mm lens would be a good choice, this is easily hand held >under most lighting conditions. What do you think about IS in general? Works *really* well for me on my 10x binoculars, but when I tried somebody's IS Canon IS zoomed to 400mm, the stabilization did not seem as good as on the binox. I'm kind of lusting after something to allow me and my D70 to take action pix of wind surfers and kite surfers but don't have a clue... IS is attractive to me bc it holds the promise of not having to lug around a tripod and/or set one up to shoot. Understood that a decent IS lens is going to cost at least twice what I paid for the D70... SignaturePeteCresswell > Hi All, > [quoted text clipped - 6 lines] > > Terry In looking at a few photos of planes that I have it looks like the number are a fair bit larger then 5 inchs, closer to 12 would be my guess, where are you getting the 5 inch number? Scott > In looking at a few photos of planes that I have it looks like the > number are a fair bit larger then 5 inchs, closer to 12 would be my > guess, where are you getting the 5 inch number? > > Scott T'was a guess. Judging from your experience -- sounds like a bad guess apparently. Scott: FYI, from my years as a controller from long ago before Reagan and I had a disagreement in terms and conditions of employment: The letters on an airplane were 5" high as you have seen. However, to better enable aircraft ID the standard was raised to 12" so they could be read more easily. I can't remember if it was a mandatory change for all aircraft, but I suspect not. So, you will see both sizes in the aviation field. Hope that helps clarify that point. I'd just suggest any digicam with a 100mm (equiv.) to 140mm lens - and then enlarge the hell out of the images with PhotoShop. It works great for such stuff. No $4 to park! No $6 admission! http://stores.ebay.com/INTERNET-GUN-SHOW > Hi All, > > I need to be able to read aircraft registration numbers from one > quarter mile away. These numbers are about 5" or so tall. What size > telephoto lens will do this? How far away can you take a photo with a 50mm lens and read the numbers? 100'? 200'? 300? Divide that distance into 1,320 for your multiplier; eg, 1320/100 = 13.2 * 50mm = 660mm. -- dadiOH ____________________________ dadiOH's dandies v3.06... ...a help file of info about MP3s, recording from LP/cassette and tips & tricks on this and that. Get it at http://mysite.verizon.net/xico > I need to be able to read aircraft registration numbers from one quarter > mile away. These numbers are about 5" or so tall. What size telephoto > lens will do this? Terry, 450mm will get you there (i.e., a 300mm film lens on a digital body). Crop before printing. Here are some practical examples: http://www.pbase.com/hornbaker/misc These were shot ad-hoc, lowest-grade settings (high ISO, cloudy lighting, highest compression). I'd gauge the distance at 1/4 & 1/2 mile. Camera / lens details are listed with the images. The lettering looks at least 12" high, though even half their height would be legible, especially with sharper settings. Photoshop Elements will get you the cropping you need for ~$70; there are certainly other free/cheaper options. Richard > 450mm will get you there (i.e., a 300mm film lens on a digital body). > Crop before printing. [quoted text clipped - 8 lines] > will get you the cropping you need for ~$70; there are certainly other > free/cheaper options. Excellent. Those are exactly what I'm looking for. Thanks. |
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