Re: optics/Japan

[David Dockstader <DRDOCK00@UKCC.UKY.EDU>]

On Fri, 28 Nov 1997 00:11:50 -0600 brian whatcott said:
> MTF -as a camera system quality measure naturally encompasses the image as
> recorded on film. It seems to me that lens resolving power much in excess
> of the resolution of the finest grain films is ..er.. academic.
> (Or have emulsions so improved in the last decade or two?)
Now I understand.  Your MTF was for the entire system, including film.  Most
modern high quality optics at f/4 or larger are able to transmit much higher
frequencies than typical pictorial film can record.  I am used to looking at
lens and film separately since there is a wide choice of films available.  To
say that lens quality above and beyond film quality is academic is like saying
the abilty of a sound system to produce frequencies beyond the range of human
hearing is academic.  It is not quite true.  There are a lot of factors
involved.  MTF is a good way to look at it.  The system MTF is the product of
lens MTF and film MTF, so even if at a given frequency film MTF is only 40%
you can still tell the difference between lens MTFs of 80% and 90%.  The high
resolutions that I quoted earlier were recorded on Kodak high resolution glass
plates.  This is a very fine grain, high contrast emulsion, totally unsuitable
for pictorial purposes.           As you suggest, the resolution of most modern
camera lenses  is so much better than pictorial films that for all but the most
critical pictorial photography, lens resolution need not be a great concern
when purchasing equipment.  For me durability has been a much more critical
issue.  I have had grease migrate into automatic diaphrams so that they fail
to stop down all the way, had lens elements come loose, and most recently have
discovered the hard way that Sigma and Tokina hold some of their lenses togethe
r with sticky tape!  Japanese ingenuity in its finest hour.