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Re: [OM] Various lens sharpness numbers at various ap

Subject: Re: [OM] Various lens sharpness numbers at various ap
From: PCACala@xxxxxxx
Date: Mon, 11 Jan 1999 19:07:56 EST
Dave writes:

> Just how do you propose to test these setups?  I'd be interested in the 
> process so's I can test my lenses...

The basics are in the left panel on my Olympus OM Systems Lens Test WWW site
at:
http://members.aol.com/olympusom/lenstests/default.htm

The critical things are that I'm holding variables to a minimum.  Thus I shoot
the same target at the same magnification on the same film, evaluated with the
same projector lens at the same projection size.  The exposures unfortunately
have to vary +/- 2/3rds of a stop, since I'm using the stepped shutter speeds
of an OM-1 (to give me mirror lockup) and can't tweak the aperture.

Anyone who acquires the huge 1962 non-shaded relief edition of the USGS
topographic map of Grand Canyon National Park, can do the test.  Note this is
probably available for loan at most USGS map repositories, which in most cases
are university library map collections.  It might also still be available from
the US Geological Survey.  Why that map?  I had it already.  It has a mix of
low contrast and high contrast detail.  It is a real world shooting situation
for ME.  It also is huge: 60 inches wide and gives a 1:40 magnification ratio.
Small maps would favor the macros and some of the lenses wouldn't even focus
that close without extension tubes.  The map also has areas with more fine
detail than any Zuiko can handle!

Gary Reese
Las Vegas, NV

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