• Welcome to Photrio!
    Registration is fast and free. Join today to unlock search, see fewer ads, and access all forum features.
    Click here to sign up

OM-1/OM-10 light meters questions.

Notnx

Member
Allowing Ads
Joined
Aug 27, 2025
Messages
3
Location
Ekb
Format
35mm
Good day. I have two cameras: OM-1 and OM-10. OM-1 is modified with a BAT43 diode to use SR44 batteries. When used with the same lens and ISO400, I get different shutter speeds at the same aperture. Actually, you can see it in the photo: OM-10 offers 500/250 speeds, OM-1 at 250 speed gives insufficient exposure, at 125 it is already exceeded. What could this be connected with, and how can I make sure that the readings are correct? Should I use a third-party exposure meter application for testing?
 
Test it using a uniformly lit surface e.g. a wall. The bright light in your frame will give twitchy readings.
 
And don't forget that there are actually two meters in the OM-10. The one that controls exposure in auto mode measures light reflected off of the film plane, and depends on film being present for accuracy. The meter in the viewing system is probably not as advanced in many ways as the metering in the OM-1.
 

Most OM-1/1N I service (after adding diode for silver oxide conversion) are still off 1.5 to 2 stops when tested on a Kyositsu EF8000 tester. Mechanical adjustment is usually needed (changing pulley positions). In your setup, you don't really know which camera is correct without a known calibrated light source.
 
You must log in or register to reply here.
Menu
Log in
Register