[filmscanners] RE: 3 year wait

["Austin Franklin" <darkroom@ix.netcom.com>]

Hi David,

> The point of the discussion been lost. The question was resolving detail,

You are correct.

> Film resolution is usually stated as two numbers: for a 1000:1
> pattern and a
> 1.6:1 pattern, and most film is 50 or 60 lp/mm for a 1.6:1 pattern. That's
> what Anthony was trying to say, I think.

Anthony made the following statement:

"It might well be fairly routine to see a ten-stop spread in a single scene
on the surface of the Moon, but here on Earth, it's unusual, even rare."

Which is just plain not true.  10 stops is not hard at all to get in a
single scene.  The correct point, as you said, is that the high contrast of
1000:1, though it may be in the image, isn't the same as 1000:1 high
contrast highly localized line pairs.  That I agree with.

Scanner sampling is a very important issue with respect to the results you
get from film scanning, in a way most people seem to forget.  A 4000SPI
scanner is able to (reliably) SEE something that is 1/4000th of an inch IF
and ONLY IF it lines perfectly up with a sensor element.  A 4000SPI scanner
actually only has a RELIABLE scanning resolution of slightly more than
2000SPI UP TO 4000SPI.  So, the point is, even at 60lp/mm, that's
3048lines/inch...you need to sample at twice that to RELIABLY detect
something that is 1/3048th of an inch.

Lense resolution will also lower the actual recorded to film resolution a
bit, but not by much.

Regards,

Austin

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