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[filmscanners] Re: film and scanning vs digital photography



From: "Arthur Entlich" <artistik@shaw.ca>
>>>>>>>>>>>>>>>>

Well, that actually raises another issue.  Silicon will probably never
be as thin as film emulsion, and that is a problem.  It is why lenses
required redesigning, because light that arrives at an obtuse angle to
the CCD/CMOS/whatever sensor has to travel through a fairly thick and
changing thickness of sensor cover.  This leads to problems with color
fringing, distortion, light falloff, defraction, and other aberrations
of light which are pretty much avoided due to the very thin nature of
photo emulsions.
<<<<<<<<<<<<<<<<

I don't buy it.

I'm too cheap to buy a film EOS and test myself, but everything I've seen
indicates that FF digital is simply better than 35mm film for wide angle
work. (1) The angles aren't all that steep. The shortest flange-to-sensor
distance in the APS-C and larger dSLR world is 44mm, so the steepest angle
is about 27 degrees off vertical (63 degrees from the sensor)* when stopped
down. (2) The dome-shaped microlenses means that light falloff is slightly
less with a digital sensor than film for the same lens. And (3) the flatness
means you don't get killed by the fact that depth of focus gets narrower
with shorter focal lengths.

In real life, the superwides I own are rather iffy lenses and need to be
stopped down to f/11 (17-40) or f/16 (Stigma 12-24) for the corners to
sharpen up. But they make nice sharp 12x18 prints. (At 12mm, it's quite hard
to persuade the Stigma to cough up sharp corners. I'm still working on it.)

The coke can and cigarette butts in the shadows are rendered fairly well in
the following.

http://www.pbase.com/davidjl/image/73874666/large (click original for a 6MP
version)

*: Someone check my math here: the diagonal is sqrt(12^2 + 18^2) = sqrt(144
+ 324) = 22mm, so that's tan^-1(0.5) = 26.6 degrees.

David J. Littleboy
davidjl@gol.com
Tokyo, Japan


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