Olympus-OM
[Top] [All Lists]

[OM] Laser Tests on Various Lenses

Subject: [OM] Laser Tests on Various Lenses
From: Joel Wilcox <jowilcox@xxxxxxxxxxxxxxxxxxx>
Date: Mon, 31 May 1999 20:45:52 -0500
Oly Shooters,

As promised, I've killed an afternoon in the basement bouncing laser beams
off mostly Zuiko glass.  When I did this before, I mounted a laser pointer
on a 200/f4 and pointed it at a wall about 10 feet away.  I shot with both
the OM-1 and OM-2S. I think the original purpose was to look for reasons
why Gary's results for the 200/f4 were so poor, but having identified an
apparent difference between the OM-1 and the OM-2S, I became interested
both in the performance of the 200/f4 and the OM-1.

Gary has since retested the 200/f4 to show it is as good as people felt it
was. He has also tested the 250/f2 with both OM-4 and OM-1 and the shots
with the OM-1 were not as good as with the OM-4.

This has prompted me to do further laser tests with a variety of lenses
using both the OM-1 and OM-2S for mounts.  Here are the lenses tested for
stability in combination with both cameras:

50/f3.5 macro
85/f2
Vivitar 100/f2.8 macro
200/f4
35-105/f3.5-4.5
85-250/f5
2X-A teleconverter (with 200/f4)

Setup:  Bogen 3221 tripod on concrete floor with plastic feet, almost fully
extended legs;  3030 pan-tilt head with QR plates;  laser pointer mounted
to second tripod and pointed at an angle at each lens so that laser was
reflected to flat side of floor joists above. A filter was required to
reflect the laser beam properly (no mirror necessary).  I used MLU and
timer on OM-1, but I also did some retests using the timer WITHOUT MLU;  I
used timer MLU/aperture pre-fire with the OM-2S.  I tested the
"troublesome" shutter speeds from 1/30 down to 1/2.  I set aperture to f11
or f16 (1 or 2 stops more open than fully stopped down, depending on the
lens) so that aperture stop down was involved.  Bouncing the laser off the
lens allowed me both to test more lenses and to amplify the sensitivity of
the test because the laser was bounced much further than in my previous
tests.  I was able to discern slight movement in cases where I couldn't see
any movement previously. 

Observations:  Camera shake or vibration must be characterized differently
depending on lens.  In some instances it occurs as a jerk or a kick, where
it would appear that the laser point would actually move slightly to the
left or right and stay there.  Sometimes the movement would appear as a
slight shift to one side and then back again.  Other times there would be a
sort of bounce or vibration up and down. Who knows how much human error
(mine) is involved too?  I often repeated shutter speeds and very slight
movements seemed sometimes to be slightly "different."  I am forced to
wonder whether the mechanical element of the timer on the OM-1 contributes
something slightly different each time depending on how far one winds it.

Results:

50/3.5 macro

        OM-1:  jerk or kick at all speeds
        OM-2S: no discernable movement

85/f2

        OM-1:  very slight movement at all speeds 
        OM-2S: slight movement at 1/15-1/30, none at 1/8, very slight at 1/2-1/4

Vivitar 100/2.8 macro

        OM-1:  jerk or kick at all speeds
        OM-2S: very slight movement

200/f4 (without telephoto lens support)

        OM-1:  up and down movement at all speeds
        OM-2S: none at 1/30, slight movement at other speeds

200/f4 with telephoto lens support (Bogen 3420)

        OM-1:  very slight movement at higher speeds, slight shift at stopdown 
at
1/2-1/4
        OM-2S: very slight movement at all speeds

Note:  Of the three holes on the bottom of the support for mounting the QR
plate, the middle and rear hole closest to the camera produced the same
results, the hole closest to the front of the lens was worse and shouldn't
be used.

200/f4 with 2X-A and tripod collar

        OM-1 unacceptable bounce at all speeds
        OM:2S: unacceptable bounce at all speeds

200/f4 with 2X-A and Bogen telephoto lens support

        OM-1:  very slight kick at all speeds
        OM-2S: very slight movement at 1/30, none at 1/4-1/15, slight aftershock
at 1/2

35-105/f3.5-4.5

        OM-1:  none at 1/30, very slight at other speeds
        OM-2S: very very slight at 1/30, none at other speeds

85-250/f5 with tripod mount

        OM-1:  no movement
        OM-2S: no movement

Re-test of 50/3.5 macro + OM-1 WITHOUT MLU

        OM-1:  slight movement at all speeds, improved by comparison to test 
with MLU

Re-test of 85/f2 + OM-1 WITHOUT MLU

        OM-1: slight movement at all speeds (same as with MLU)

Conclusions:

Lots of counter-intuitive data.  Whereas the 200/f4 continues to look like
a tricky lens, the performance of the zooms is remarkable.  The 85-250/f5
on its tripod mount is incredibly stable, given all the other variables in
my system.  Similarly the 35-105 is slightly less good with the OM-1 than
the OM-2S, but still almost as good.

On the notion that tripod mounts might be the ticket, I wrapped electrical
tape around my 2X-A teleconverter to make the tripod mount off the 85-250
fit.  Wasn't acceptable, and certainly the combination of 2X-A + 200/f4 and
telephoto lens support was a much better performer.

The performance of the 50/3.5 macro with the OM-1 with MLU was so
apparently horrible that I wondered how much worse it might be without MLU,
and lo and behold, the results were surprisingly better. I tried the same
thing with the 85/f2, but performance was about the same with or without MLU.

In my previous tests the OM-2S was just about "perfect."  With the
amplification of the laser, I was able to show that there is some movement
with the OM-2S as well as the OM-1.  All things being equal, one would
think no movement is better than some movement, but one still needs to
consider a complex of factors among cameras and lenses.  Something about
the 85-250/f5 makes both the OM-1 and OM-2S look good.  But with the 50/3.5
macro, there almost seems to be a bad synergy with the OM-1.

The lone non-Zuiko, the Vivitar 100/2.8 macro, seems to have less good
synergy with both the OM-1 and OM-2S than the Zuikos, on the whole.  It is
a very heavy lens with perhaps more of its weight out front than even the
heavier Zuikos.

Despite how things might appear, one still does not know how any of this
might translate to film.  A good place to start might be with the 50/f3.5
macro where one might expect a marked difference in sharpness between shots
made at the critical shutter speeds with the OM-1 and OM-2S. I guess that's
where I'm headed next.

 




Joel Wilcox
Iowa City, Iowa USA

< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >


<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz