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Old Jun 4, 2009, 2:06 PM   #11
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It seems you understand my question. Everyone here got very technical with my wording but I know what I meant. Using the terms I chose seemed to be the simplest way to word my question. So far though everyone is telling me its meaningless when its not.

Ive shot 35mm film for a long time and would like to go digital SLR. Id like to be certain that the lenses I choose for the digital will give the same field of view Im used to. If I take my 18mm lens and put it on a digital SLR body with a 1.5 factor I will get the field of view similar to my 27mm lens on the 35mm film body. I have a point and shoot digital camera and the quoted focal lengths are given as 35mm equivalents. The 35-100mm stated yields a field of view equivalent to a 35-100mm lens on a 35mm film camera.

Im not a photography newbie but I didnt know if the lenses supplied with digital SLR bodies are also 35mm equivalents for field of view. This is most important to me at wide angles. With a multiplier of 1.5 I would need a 10mm lens to give me the field of view of a 15mm lens on my film camera. Ultra wide lenses are expensive.

Last edited by abnerheggs; Jun 4, 2009 at 2:11 PM.
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Old Jun 4, 2009, 2:56 PM   #12
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Double post, sorry!

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Old Jun 4, 2009, 2:57 PM   #13
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I find it rather useful that the 'exif' data attached to almost all digicam images has two lines similar to this in it (or amendments according to focal length)...

>>
Focal length [mm]: 16.2
35mm focal length [mm]: 96
<<

One indicates real life, the other indicates life in the old 35mm film camera world, where 50mm was a 'standard' lens, 35mm or even 28mm was 'wide angle', 80mm was a 'portrait lens', and anything much longer, typicallly 135mm was 'telephoto'. Nowadays, it depends on your sensor size.

Have fun with your calculators!
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Old Jun 4, 2009, 3:24 PM   #14
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Quote:
Originally Posted by abnerheggs View Post
Im not a photography newbie but I didnt know if the lenses supplied with digital SLR bodies are also 35mm equivalents for field of view. This is most important to me at wide angles. With a multiplier of 1.5 I would need a 10mm lens to give me the field of view of a 15mm lens on my film camera. Ultra wide lenses are expensive.
The focal length engraved on the lens is the actual focal length, so, yes, you'll have to do some math in your head. The focal length of a lens doesn't change with the camera body it's attached to. An 18-55mm lens actually has a focal length of 18-55mm. What changes is the angle of view, not the focal length.

Yes, a 10mm lens on an APS-C dSLR will have the same angle of view as a 15mm lens on a 35mm film SLR. Yes, an 18mm lens on an APS-C dSLR will have the same angle of view as a 27mm lens on a 35mm film SLR.

The term "Lens Multiplier" is a misnomer. The focal length of a lens isn't multiplied. The image is cropped from the size of a 35mm film exposure, so a more correct, and more widely accepted term is "Crop Factor".

Last edited by TCav; Jun 4, 2009 at 3:28 PM.
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Old Jun 4, 2009, 4:34 PM   #15
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Another think that people can easily get confused by if they are told that a 150mm lens on a FF camera is the same as a 100mm on a APS-C camera is what happens with the depth of field.

A shot the same distance away (let's assume 25') using the above example of lens/body if taken at the same aperture (let's assume f2.8) will have quite noticeably different results with the out of focus areas. So field of view is the same in the combination but other elements vary.
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Old Jun 4, 2009, 6:23 PM   #16
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Years ago I worked in a studio. We used 4x6cm 6x9cm and 4x5inch cameras. No 35mm but I used it for my personal stuff. With each of these formats you need different focal lengths to achieve the same angle of view.

I never thought about it. Never did any math. Never even considered there might be math to do. I knew the general principle. (The larger the film size. The wider the angle of view with any given focal length.) But after a short while you didn’t think about that either. You just knew what lens to grab for the angle of view you wanted on the system you were using.

Then along came DSLR’s and the DX sensor. Same issue just a new format. All of a sudden everyone is making a big deal out of the “crop factor” or “multiplier” witch ever term you prefer.

Now I’ll admit doing the math can be helpful when you first make the switch from film to digital. But it’s useless to anyone not familiar with shooting 35mm and should quickly become unnecessary to those who are.

Now if I could just get used to autofocus as easily. Its driving me nuts.
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Old Jun 4, 2009, 7:51 PM   #17
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Now if I could just get used to autofocus as easily. Its driving me nuts.
I still have trouble with the idea of changing the "film speed" in the middle of a "roll".
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Old Jun 4, 2009, 7:58 PM   #18
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I still have trouble with the idea of changing the "film speed" in the middle of a "roll".
True, but it's a good job you can as shooting hundreds of frames on a roll would mean you having to wait a long time LOL.
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Old Jun 5, 2009, 1:00 AM   #19
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True, but it's a good job you can as shooting hundreds of frames on a roll would mean you having to wait a long time LOL.
Sure, but you can change 'film' in the middle of a roll too, and without worrying about exposing it. Wouldn't I get confused if each memory card had a fixed speed

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Old Jun 5, 2009, 3:55 AM   #20
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Quote:
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I still have trouble with the idea of changing the "film speed" in the middle of a "roll".
Well, I regularly did that in effect, by accident, by getting the exposure wrong, but being rescued by colour negative film with its wonderful latitude, assisted by a second printing stage!
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