Archived posting to the Leica Users Group, 2003/02/14
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At 3:05 PM -0800 2/14/03, Jacques Bilinski & Barbara Bradbury wrote:
> > infinity. A Summilux wide open would show this discrepancy easily. A
>> Noctilux would focus at about 12m with the same film - flange
>> discrepancy; that is why it is easier to see with a wideangle lens.
>>
>I understand that with a wideangle a discrepancy would cause the lens to be
>focused at a closer distance than with a longer focal length. My point is
>that at the same f stop both images of an object at infinity would be
>equally fuzzy. Do you agree? I guess that when you are doing these tests
>you are determining the distance of optimal sharpness. Then I can understand
>that if the distance is closer with a WA it is easier to identify.
Yes, a point at infinity is just as fuzzy with either lens. However,
with a longer lens more is fuzzy in any case, so the fuzziness at
infinity does not stand out as much, and if an object that is quite
close is sharp instead of infinity, that is more noticeable than if
an object in the middle distance is sharp instead of infinity. If the
latter, you might assume that you focused incorrectly.
If you are actually testing for this, you're right, the focal length
does not matter. If you are just shooting, the discrepancy will
become obvious more readily with the wider focal lengths.
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* Henning J. Wulff
/|\ Wulff Photography & Design
/###\ mailto:henningw@archiphoto.com
|[ ]| http://www.archiphoto.com
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