Canon says: more EF-S lenses

Started Oct 6, 2004 | Discussions thread
bds231
Regular MemberPosts: 404
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Re: Canon says: more EF-S lenses
In reply to Daniel, Oct 9, 2004

Sorry ZiPA, it's a matter of physics, not beliefs.

Assuming the lens in question is well-designed and made, distortion is directly dependent on field of view. As I wrote above, there's nothing inherenly "wide angle" about a 28mm lens -- it's only "wide angle" if it's designed to cast an image circle with a diameter longer than its focal length (as a 28mm designed for use on a FF sensor is).

Therefore, if all you know about a lens is that the focal length is 28mm (eg., you don't know the size of the image cirlce), you can't say anything about the amount of distortion that lens displays.

Daniel wrote:
No, I don't know believe this is correct. The digicam example is
not comparing apples to apples. 1.6x crop in DSLR is just a crop
which give you the sample results as FF DSLR but with crop so you
will still see the distortion from WA lens. You can take a picture
with a FF DSLR at 28mm and crop it in photoshop which will look
like 1.6x DSLR at 28mm. The digicam with very small sensor, but
have their lens (say 7mm) is design to shed light to just on its
sensor (no crop).

I agree with ChuckH's assessment and disagrees with ZiPA.

ZiPA wrote:

ChuckH wrote:

But, it seems to me that the tendency of
a wide-angle lens to make closer objects appear much larger than
distant objects and thus result in long noses, large heads, small
torsos and the like would be just as pronounced when used with a
1.6X body as with a FF body. My understanding is that a 28mm lens
would, therefore, give roughly equivalent perspective to a 50mm
lens on a FF body, but would distort the perspective in the way we
normally associate with WA images. Am I incorrect in that
assumption?

Short answer: Yes, you are incorrect. Just take a look at a
portrait shot with a digicam with, say, a 15-20 mm lens, and you'll
see why. Perspective distortions have nothing to do with focal
length, and everything to do with subject distance.

-JP

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