Members: 76,295   Posts: 1,681,436   Online: 906

# Thread: Olympus OM-4 Multi Spot Metering

1. ## Olympus OM-4 Multi Spot Metering

I wonder how the meter in the OM-4 would calculate the multi point spot metering. I know you can measure up to 8 points. But as an example of say 3 points. You have the camera on aperture priority say f/5.6 and the measurements are 1/1000, 1/125 and 1/30 for example. What shutter speed the OM-4 would pick as the average of the 3?

2. Set my OM-4ti to ISO 100 and tried it. Answer is just over 1/125th of a second (or under if you know what I mean).

3. Thanks.
If I give 1/1000 = 10 (10 stops from 1 second)
1/125=7 and 1/30=5
Average those would give me 7.3333 so I think the shutter speed would be 1/160 second. A third stop from 1/125. Is that what you got by trying?

4. It averages the multiple readings. You can see this clearly if you watch the meter display as you pick successive points.

5. The shutter speed is a linear average of the spot metered areas. In Auto mode, it will be calculated by the camera based on TTL meter readings of the spots. In Manual Mode, it works like Match Needle metering where you still have to select Aperture and Shutter speed manually. If you want to bias the reading more towards shadow values, take two or more spot readings of dark areas.

6. Originally Posted by Chan Tran
Thanks.
If I give 1/1000 = 10 (10 stops from 1 second)
1/125=7 and 1/30=5
Average those would give me 7.3333 so I think the shutter speed would be 1/160 second. A third stop from 1/125. Is that what you got by trying?
Yes. The indicated speed was 1/3 stop faster than 1/125 so the actual speed would be around about there.

7. There is a neat trick allowing you to bias the exposure towards some areas. You can, for example, measure the same spot twice (let's say it's 1/1000), and then add another measuring (let's say 1/250). The average will be calculated as an average of three values: 1/1000, 1/1000 and 1/250.

 APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:
Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin