[OM] Night exposures with OM-2SP - warning long message, but ON topic

[Wayne Harridge]

Dear Zs & Zs,

Last week I took some night time exposures with my recently acquired OM-2SP.
When I got the transparencies back (Kodak Elite 100) the exposures were
right off, over exposed.  At the time I was taking the shots I thought the
shutter was staying open too long in comparison with what I had experienced
under similar lighting conditions with my OM-2N.  All other transparencies
where the exposure was shorter than 1 sec seemed to be accurately exposed.
I thought I would investigate and compare the behaviour of the 2 bodies, so
I set each one up in turn as follows:

Mounted on tripod
A short piece of unexposed film in the film gate
ISO dial set to 100 with no compensation
50mm f1.4 lens with 4x ND and polarizing filter (to reduce the amount of
light and force a long exposure)
Normal room lighting with lens pointing at a blank wall

I then exposed a number of shots at different apertures with the following
results:

Aperture             OM-2SP              OM-2N

f1.4                      6 sec                    3 sec
f2                         8 sec                    4 sec
f2.8                      21 sec                  7 sec
f4                         114 sec                14 sec
f5.6                      128 sec                 28 sec
f8                         128 sec                 55 sec
f11                         -                         100 sec
f16                         -                         183 sec

Note:

1. Exposure times are average of at least 3 exposures timed with stop watch.

2. From f2 to f11 with OM-2N exposure times almost exactly double with
aperture as expected.

3. From f1.4 to f2 looks like the lens is not letting though 2x the light at
f1.4 as at f2 !

4. OM-2SP exposures are all wrong, 128 secs is probably the limit to long
exposures (OM-2N is around 225 secs from previous experience).

Anyone else like to try the same experiment with their OM-2SP ?  I would be
interested to find out if it is my particular body or "normal" behaviour for
this model.

Wayne Harridge
Ivanhoe, Victoria, Australia


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