Re: [Leica] Keystoned images

[Henry Ambrose <digphoto@nashville.net>]

>I recently photographed a number of framed  paintings on behalf of a
>co-worker, a budding but gifted artist, who wished to have several sets of
>slides to leave with gallery owners. The budget? Minimal, definitely not
>enough to cover medium or large-format expenses, particularly when the need
>to scan images was considered.
>
>Lacking a 35mm SLR, I arrived with tripod, my M6, 35 and 90 Summicrons, and
>a 50 Elmar. Lights and reflectors? I don't own any, and figured I didn't
>want to be experimenting on the spot. I had anticipated the possibility of
>an open shade situation, and brought Ektachrome 100SW, another conservative
>choice that I know well.
>
>The lighting, I could see, was going to be tricky, as there was a good deal
>of indirect sunlight from a window just off to the righthand side of the
>paintings. I had been very careful to arrange for a time when the sun wasn't
>shining directly through the window, but it nevertheless made for some
>rather uneven illumination. How to expose? Bracketing would've been handy,
>but due to the number of useable images needed, and the tight budget, that
>wasn't real practical. Finally opting for simplicity, I took a Zone VI
>reading from the palm of my hand, placed near the center of the painting,
>and did not vary the settings, though I did recheck exposure periodically.
>An incident-type meter would've been a bit handier, but using this trick, my
>Pentax spotmeter worked fine.
>
>A good deal of lens-swapping and repositioning of the camera was involved,
>and my current feeling of the Arca-Swiss B1 + Leica M combo is that it's a
>poor match, as the Arca is clearly optimized for much heavier loads, and the
>M's baseplate flexes a lot under the heavy drag, even with the Really Right
>Stuff QR plate in use. But again, it's all I had, and it's kind of rare that
>I use a tripod with small-format cameras anyhow.
>
>The results? Not bad at all! Exposure and color rendition throughout was
>almost exactly as planned, and I think my co-worker will make a fine
>impression with those gallery owners. An unwelcome surprise was discovering
>that most photos show keystoning in exactly the same way: Narrower on the
>left, wider on the right. Evidently, my camera's finder has some heretofore
>unnoticed distortions, at least in the 1.5-2.5 meter range-anyone else seen
>this, and is it just an inherent thing at these working distances, or what?
>
>Aside from these optical distortions in the finder, and an approximately 1/3
>stop error in the light meter, my late model M6 (maybe three years since it
>left the factory?) hasn't had any problems at all--no scratched negatives,
>no hassles with the rangefinder alignment, no nothing.
>
>Jeff
>
>
You'll probably do better at eliminating the keystoning by very carefully 
measuring the position of the camera (lens) and being sure it is centered 
and square to the object being photographed. Triangulate the position of 
the camera left and right then up and down. Another way would be to set 
up the camera and tripod and view through the lens (back open, shutter on 
B) then load it and put it back on the tripod. All subsequent shots would 
need to have the subject carefully set on the same center. This obviously 
only works before you load the camera!

Henry