Archived posting to the Leica Users Group, 2007/11/05
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 9:09 AM -0500 11/5/07, Leonard Taupier wrote:
>Hi Henning,
>
>I value your opinion on lens performance tremendously. You pay
>attention to these details. I only use my photos to draw my own
>conclusions. Before I retired one of my jobs in charge of quality
>control for my company was to photograph the insides of burned out
>buildings and to document the artifacts of the fire that may have
>caused a problem. My tools of choice were the Nikon N70 body and the
>Nikon AF 28-105 zoom. To this day I still think this zoom has
>perhaps the least amount of distortion of any zoom I have ever used.
>It is my reference. But it is not that wide in this age of digital
>cameras and 1.3 to 1.6X crop factors. If I don't see distortion in
>my photos then it doesn't exist. I don't see distortion in my WATE,
>my Nikon 14mm and my Nikon 17-35 zoom. You can probably measure it
>in a lab but I don't see it. I can't comment on the CV lenses except
>for the vignetting, which I saw. The Canon zooms were so bad I
>couldn't fully correct the barrel distortion in CS2. My advice if
>you own one is to enjoy it because it is a very sharp and contrasty
>optic. Just stay away from straight lines towards the edges of the
>frame. On a 20D body the 24-105 is much less of a problem.
>
>Len
>
Len, what you've said highlights one of the main points in this
discussion. If you don't use the full image circle, the lenses aren't
so bad (not so wide either, of course). The 24-105 is generally OK on
the 20D etc., the WATE is fine on the M8 and the 17-35 is fine on the
Nikon D200. The Canon 16-35 is not OK on the 5D, and the Nikon wides
won't all be fine on the D3. The distortion increases as you get
closer to the corners.
Linear distortion is a function of variable magnification, and this
gets harder and harder to control the wider the angle of view. Very
wide angles of view and distortion go hand in hand for the most part
with retrofocus lenses.
As far as correction goes, if a number of photos are taken with the
same lens, it's very easy to set up a batch correction for them, and
do them all at once. If the camera, lens and focal length are the
same, it's very easy. If the lens is recognized by the PT lens
plug-in through the EXIF data, the lens and the focal length don't
even have to be the same for a batch processing operation to work.
--
* Henning J. Wulff
/|\ Wulff Photography & Design
/###\ mailto:henningw@archiphoto.com
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