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Re: [Rollei] Re: OT: Imacon worthiness!

- ----- Original Message ----- 
From: "Eric Goldstein" <egoldste  >
To: <rollei  
Sent: Friday, May 16, 2003 6:57 AM
Subject: [Rollei] Re: OT: Imacon worthiness!

> Austin Franklin wrote:
> > That's actually not true.  MF and LF lenses don't have
as high an MTF as
> > 35mm lenses do.  The advantage of MF and LF is purely in
the film size.
> Irrespective of film format... because a lens does not
have a high MTF, it
> is not worth shooting?
> Eric Goldstein
  Whether the above is true or not (I have doubts) what
counts as far as the scanner is concerned is the detail on
the FILM. This will be less than either film or lens
resolution. Very approximately it is 1/T = 1/F + 1/L where T
= Total resolution, F = is film, L - Lens.
  Either film or lens must be very much better than the
other to be the limiting factor.
  The highest resolution modern films have resolution on the
order of 100 to 200 lp/mm for high contrast (1:1000)
targets. The best modern lenses at working apertures are
probably about the same. If you can get on the order of 60
lp/mm for high contrast targets on the film you are doing
very well. Lower contrast targets (one standard is 1:30)
result in much lower resolution numbers.
  Because scanned systems have quite different
characteristics than continuous ones there is no direct
conversion from one to the other. Also, digital scanners
generally are not specified in terms of resolution.
  This is a rather expensive scanner. One wonders about what
audience this store thinks its getting to. Most buyers of
medium end scanners would know a lot more about them than
these folks think. Of course it could have been a joke, was
there a smiley face on the ad?
- ---
Richard Knoppow
Los Angeles, CA, USA