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  1. #11

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    Quote Originally Posted by Dan Fromm View Post
    About distortion. As has been pointed out, w/a lenses for large format cameras have low distortion. The standard w/a lens effect -- objects near the lens are much larger on the negative than distant objects; think big nose, small ears -- is sometimes called distortion. T'ain't so, failure to render straight lines as straight lines is distortion.
    ... i was referring to barrel distortion ( big nose small ears ) ..

  2. #12

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    That's not barrel distortion. Barrel distortion converts this || into this ()

  3. #13

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    Thank you for all your great insights, I am delighted that I joined this forum its a great motivation to keep taking photos and especially film photography.

  4. #14

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    90 is kinda the middle of the wide-angle pack and relatively versatile. There was a time when photo
    schools, given the general poverty of students in general, recommended that the first lenses to be
    purchased for 4x5 would be a 210 (good image circle and tight enough for head and shoulders portraiture) and a 90 (interiors, studio setups). This simple combination allowed most bases to be covered, at least at a teaching level. Only relatively recently have lenses shorter than 90 been available
    with significant wiggle room for movements. That is always a primary concern.

  5. #15

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    One of the reason to start this thread is so I can understand wide angle lenses more because I dont use them even in 35mm.

    But the other one is because of this Unique camera that I have acquired.

    Will post a new thread

    here a sneek peak Click image for larger version. 

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  6. #16

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    One of my favorite lenses on my 35mm Contax was my 25mm wide angle. After I purchased my Tachihara 4x5 I picked up a 75mm lens since I read that you take the focal length you like for your 35mm camera and multiply it by three and it will give you a rough equivalent. Well, the 75mm lens felt too wide for me, more like a 20mm lens on 35. I replaced it with a 90mm and have been very happy.

    What focal lengths you end up using on your 4x5 camera may not be the mathematical equivalents of the lenses you now use on your 35mm camera. With me it took a little trial and error to find what I like. Fortunately you can buy used lenses, try them out, and them resell them for close to what you originally paid. I just figured the little money I lost as a cheap rental fee.

  7. #17
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    Some thing that always bugs me (especially these days when people talk about 4/3 digital sensors have a "2x" crop factor to FF), is that there's no *easy* calculation between format sizes when they're a different shape.

    Take a 4x5 frame, actual image size is 94x120mm (numbers I got from a bit of googling) and a 35mm frame size of 24x36 (may be optomistic for film, but it's the size of digital FF at least).
    The 4x5 has a ratio of 1.27:1 (near enough a 5:4 ratio), the 35mm has a 1.33:1 (6:4 or 3:2 ratio).

    So what do you want your output image ratio to be?
    Take the 4x5 and crop it to a 3:2 ratio (or anything 'longer'), then the image is 120x80mm. Then compare lens sizes to get the exact same framing and DOF your SuperAngulon 65mm f/8 is the same as putting a 19.5mm f/2.4 lens on your 1DX. 90mm f/8 is the same as 27mm f/2.4. That's a "divide by 3.3" rule of thumb.

    But what if you want a 4:5 print size? (or 8X10, 16x20, or anything 'squarer'). Then you have to crop the 35mm frame to 30x24mm (and the 4x5 frame to 94x117, but near enough). To get exactly the same framing and DOF, your 90mm f/8 Super Angulon will give the same image as a 23mm f/2.0 on a 35mm. Your 65mm f/8 will give the same as 16.6mm f/2.0 on FF. That's a "divide by 4" rule of thumb.

    Anyway, most of that is beside the point. Freaking wide is Freaking wide. (and that's wide, I've got the sigma 8-16mm on my digital-crop, widest it gets until they make a <43mm on 4x5). It's already been said, but "distortion" in the true sense is Barrel Distortion, think of what a fisheye lens does, that's barrel distortion. "Wide-angle" distortions are the "big-nose-small-ears", as well as "falling over buildings" phenomena (if your lens is not 100% horizontal). Both are made worse by barrel distortion, and both tend to happen together on the widest lenses because they're pushing the extremes of lens design to get that wide (especially on SLRs). Google the Samyang 14mm, or EFs 15-85 at 15mm, or EF 28-300 at 28mm for sample pictures of extreme barrel distortions.

    As has been said, on SLRs they're all Retrofocus designs to clear the mirror box. Focal lengths of 12-35mm are less than flange distances of 40-50mm.
    Luckily on LF (and rangefinders), you can get away with Biogon designs, symmetrical (or almost), not much room between the lens and film but doesn't have to be, and very very low distortion. I haven't got numbers, but I'm guessing that the Super Angulons of today do better than all but the best SLR designs.

    Back to the OP, why is 90mm the 'standard'? Because lens designs back in the day of "angulons" could only get so wide in terms of degrees of coverage, and 90mm just happened to be the length that covered 4x5 nicely (wide open and/or with movements, whatever the market thought was 'good enough'). Flash forward and "super angulons" can cover a wider image circle, so 65mm can now cover what was only possible with 90mm before. It's even wider now, Super Angulon XL covers 4x5 and then some at 47mm focal length.
    An awful lot of electrons were terribly inconvenienced in the making of this post.

  8. #18

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    Quote Originally Posted by Dr Croubie View Post
    Back to the OP, why is 90mm the 'standard'? Because lens designs back in the day of "angulons" could only get so wide in terms of degrees of coverage, and 90mm just happened to be the length that covered 4x5 nicely (wide open and/or with movements, whatever the market thought was 'good enough').
    Only so wide? Is that so? See http://trichromie.free.fr/trichromie.../27/PERIGRAPHE ; http://www.cameraeccentric.com/html/info/zeiss_3.html , p. 36; http://www.cameraeccentric.com/html/info/cooke_2.html , p. 9. Re the Cooke Anglic, at 100 degrees the 2.5 incher covers more than 4x5. And let's not forget the widest of them all, see http://www.cameraeccentric.com/html/info/goerz_2.html , p. 35

    You shouldn't make things up.

  9. #19
    Dr Croubie's Avatar
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    Well, I didn't mean that they were the widest technically possible at the time, but what the 'market' can tolerate in terms of manufacture, affordability, even mass appeal for their 'look' is always a while behind the 'bleeding edge' that is technically possible.
    Take SLR lenses today. From sigma you can get 8-16mm on crop and 12-24 on FF, but they're not the best IQ at the widest ends, and not very big sellers compared to the widest that the big boys go, 14mm from Canon and Nikon and 15 from Zeiss. And even then, zooms like 16-x and 17-x (on FF) are a lot more popular, from price or portability or whatever reason, a lot of people might just think it's "too wide", but tastes change. And again, it wasn't that long ago that 16, 17, 18mm was 'available', but 24mm was the 'standard'; before that were the days when 28mm was 'standard wide' even if wider was available.
    If anything, I reckon the market is pushing the manufacturers to go wider and wider (I know i can't ever seem to get wide enough), soon enough we'll have zoom lenses going to 13mm or wider, and primes maybe to 10 or 11mm. Doesn't mean it'll ever be 'standard' in everyone's kit though...
    An awful lot of electrons were terribly inconvenienced in the making of this post.

  10. #20

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    Interesting. You made a false statement re coverage attainable with "old" technology and then denied you meant it. And then you rambled about what's coming to market for small chip digicams. Why didn't you bring up the use (or abuse) of really short cine lenses on micro 4/3 digicams? Why didn't you mention fisheye lenses? I mean, if you're going to muddy the water, muddy it thoroughly.

    Lessee now. The APS-C chip's dimensions are 24.1 x 16.7 mm, its diagonal is 30.1 mm. An 8 mm lens that covers 30.1 mm has to cover 124 degrees. The Goerz Hypergons I directed you to cover 135 degrees.

    Ultrawides aren't generally useful, in LF they've been used mainly for specialized applications. I like 'em, my widest is a modern lens that covers 120 degrees, is rectilinear and gives good image quality. It isn't the lens I use most. In truth, the larger the format the more useful utrawides are 'cos the larger the format the more fine detail can be captured. In olden times they weren't used a lot, so weren't sold in large numbers, because of lack of demand.

    Zoom lenses aren't used on LF. Too big, too heavy, and until very recently too flary. Why did you bring them up in an LF forum?

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