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[filmscanners] Re: film and scanning vs digital photography

From: "Berry Ives" <yvesberia@earthlink.net>

Your math is good; I got 26.2 degrees off vertical.  But I don't know the
significance of that angle with respect to the sensor "tunnels".  It sounds
like a rather large angle to me.

You might do the math for, say, the Contax G-series 21mm Biogon<g>. (The
rear element of the Biogons tends to be practically touching the film, as I
understand it.)

Anyway, I've heard from two people who have tested the 5D sensor for
sensitivity vs. angle of incidence, and both found that the falloff was less
than with film.

Regarding the issue of (individual) lens-specific info being passed from the
lens to the image file, for Olympus (from their web site):

"Each Zuiko Digital Specific Lens also contains its own CPU to further
solidify a richly colored, clear image. These "smart" lenses transfer data
specific to the lens being used to the system's software to correct
potential distortions and aberrations that occur in all lenses. Pin
cushioning, barrel distortion, shading and other unwelcome phenomena can be
eliminated with the single touch of a button in software."

The 4/3 sensor is 1/4 the area of the FF sensors, and not really a serious
format. If one is concerned with image quality.

Meanwhile, the lens name makes it into the EXIF information in most SLRs for
most lenses, and some software will do the corrections for you, with some of
it automated, I think (PTLens). I haven't found the need for any of that
with either the Sigma 12-24 or the Canon 17-40 on the 5D, although I mostly
shoot stopped way down.

The place that I do need some correction help is the 24TSE (which needs
chromatic abberation correction when shifted), but the amount of shift and
tilt doesn't make it into the EXIF data, so it can't be automated.

Oh, well. I really ought to CLA the Nikon 8000, pick up a cheap EOS film
body, and do the work. But there's real work in the inbox, a guitar to be
practiced, old photographs to be processed, and new photographs to be

David J. Littleboy
Tokyo, Japan

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