ab-lnc@xxxxxxxxxxxxx writes:
<< My OM2 overexposes by roughly two stops. >>
Since I did not see anybody respond here are a few ideas.
AI,
you need to figure out if it is :
a) the shutter
b) the manual meter display circuit
c) the meter
d) the manual exposure (manual shutter speed) circuit
e) the auto exposure meter display circuit
e) the auotexposure circuit .
Based on this you can decide whether this is something you can tackle at home
or not.
Here are some pointers but it does not cover all possibilities:
If it is shutter mechanics (eg stcickty magnet,curtain etc) it should give
incorrectly exposed pictures on both auto and manual. Long exposures in
general should be affected less by this.
If the problem is on the manual meter then you can determine this by
comparing the matched metered settings to another camera or hand meter. Also
try this with different light levels since at very low and very high light
levels two different sensitivity cells are used for display metering.
The displayed setting on Auto can also be compared in the same way to a
reference camera. In general the displayed matched reading on manual makes
uses most of the same circuits and sensors as on Auto display, so errors
should occur on both. A sticky meter might give varying errors for auto vs
manual.
The manual match needle function changes the needle physical position
(aperture & ASA) while the speed ring changes the circuit electrically by
switching in different resistance values.
If the display is inaccurate on auto, the exposures at the film will often
still be correct since on Auto it uses a completely different circuit and
sensors during the actual shutter release.
If the display is correct and the camera exposes correctly on Auto, but the
actual shutter speeds are inaccurate on manual (i.e. film exposures
inaccurate on manual), it might be a dirty set of contacts on the speed ring
which is really a dual multiposition switch. Try rotating the speed dial
vigorously a number of times to try to clean it.
Similarly if the meter display is inaccurate on match needle manual only, it
might be the second set of switch contacts on the speed dial are dirty. Try
rotating the speed dial vigorously a number of times to try to clean it.
It is pretty hard to adjust things without a service manual, would recommend
sending it to a camera technician.
Regards,
Tim Hughes
>>Hi100@xxxxxxx<<
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