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[OM] Laser Test Followup

Subject: [OM] Laser Test Followup
From: Joel Wilcox <jowilcox@xxxxxxxxxxxxxxxxxxx>
Date: Sun, 06 Jun 1999 15:19:14 -0500
Oly Shooters:

In our last episode, yours truly spent most of the Memorial Day holiday in
the basement shooting an empty OM-1 and OM-2S with laser beams reflecting
off of various lenses.  After noting that the OM-1 was often considerably
bumpier with the 50/3.5 macro than the OM-2S, I decided to compare the two
cameras with film in them shooting at what are usually considered the
critical shutter speeds from 1/30 down to 1/2.

I compared both cameras with the 50/3.5 macro at each shutter speed.  I
decided that with both cameras I would also shoot a set of exposures with
and without MLU (or the OM-2S approximation of mirror prefire/aperture
stopdown).  As a control of sorts, I shot a similar round of comparisons
with the 85-250/f5 zoom.  This lens produced extremely stable results in my
laser tests with both cameras.  My hypothesis was that if there was little
difference between the slides with the 85-250 using OM-1 or OM-2S but some
noticable difference between the two cameras with the 50/3.5 macro, then
the laser tests might have some validity.

For subjects I used stationary items outdoors where I would have enough
light to cover the range of speeds.  With the 50/3.5 I shot some weathered
wood;  with the 85-250 I shot an old fire hydrant with peeling paint at
approximately the 210mm focal length.

To evaluate the results I used 50/1.8 and 28/2.8 lenses as loupes.

The results are easily summarized:  I couldn't tell the difference between
comparable shots from either the OM-1 or OM-2S.  Both lenses appeared to be
exceptionally sharp and fine, although the 50/3.5 is certainly sharper than
the zoom. (This seems like an apples-and-oranges comparison, although
perhaps it is at least significant that this relative difference of
sharpness can be picked up in the scans).  If the laser tests are valid as
a predictor of anything, they either are not valid for these particular
lenses or the differences are too small for me to measure.

Also, I couldn't see any difference between shots made with cable release
and those made with MLU (of either kind).

Moral of the Story.  I am sending the OM-1 I used to Gary Reese for some
re-shoots.  Whatever he finds, I suspect the results will be "academic" as
far as I am concerned.  A "B" lens for Gary (or perhaps a "B" camera) may
in fact be more lens (or camera) than I can actually appreciate in my
normal photography.  About the same time I was evaluating these slides I
got a roll of slides back from the excursion Ken Norton and I had together
several weeks ago.  Ken and I had both come across an orange butterfly.  I
got off four frames, all with OM-2S and 50/3.5 macro, handheld.  Two of my
shots were very sharp and two weren't as good.  There was no subtlety about
this under the loupe.  I (and perhaps others) have assumed that Gary's
results are definitive in showing "good" and "bad" lenses in the same way
that two of my slides of the butterfly were "good" and two "bad."  I
suspect Gary's tests are illustrating a refinement greater than I am able
to exploit with my loupes, scanner, and printer.  Similarly, if the OM-1 is
actually "worse" than the OM-2S, I have to wonder if I can discern this in
ordinary use.  But if I can't discern it in my ordinary use, why should I
worry?  If I can't really use it, all I can do is brag about it, and I have
a hundred other ways to be obnoxious. 

The OM-1 still goes the distance for me.

If you care to try to discern things more refined by means of things less
refined, feel free to check out a web page I prepared showing both of the
settings I used with two frames from each camera at a single shutter speed,
one  with anwithout MLU. The URL is

        http://members.tripod.com/jdubikins/test/test2.htm  


Joel Wilcox
Iowa City, Iowa USA

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