Olympus OM10 - Which parts of the scene are used for metering

[ted_smith]

Hi

Can anyone tell me which parts of the scene are used for metering on the old Olympus OM10 cameras? I own 2 of them and an OM20. I gather the OM20 has a centre-weighted system but I can't find what the OM10 uses. Is it the equivalent of matrix metering (to use Nikon speak), thus taking an average of several points, or does it also use centre weighted?

I ask to account for scenarios when, for example, you have a grassy lawn, with green trees all around (so perfect 18% reflectance) but a lady in a white dress right in the middle of the scene is occupying say 35% of the scene. What does the OM10 use to measure reflectance? The white dress in the middle, or the overall scene and then average? And if it uses specific points of the frame, what points?

With my Nikon F5, I'd use centre weighted metering and +1 compensation in such a scenario probably (or I'd trust its very advanced multi-point metering algorithm that the Nikon F5 is famed for and use matrix metering). But I can't do that with the OM10 (but I could with OM20 of course, which has an exposure compensation dial).

Thanks

 

[PaulQ]

Centre weighted. The only OM to use a form of matrix metering was the 40/PC.

 

[shutterfinger]

Centre weighted.

60/40 or 70/30?

 

[PaulQ]

No idea, long time since I used one. Exposure compensation is available, red and greens marks either side of the white film speed selector.

 

[M-88]

Two things:
1. OM-10 has the same metering system as OM-2 (although with only one sensor in mirror box).

2. OM-2 has a rather unusual metering method if we trust this site:
http://www.mir.com.my/rb/photography/hardwares/classics/olympusom1n2/om2/htmls/index2.htm
It is stated that system is center-weighted, but on lower speeds it's just average (the wha?)

And I can nowhere find percentage ratio of metering system of either cameras. Not even in manuals.

 

[John Koehrer]

Wouldn't the 18% average give similar reading to an incident meter? If that's the case, no compensation. BUT if you're including
sky in the background you may want to add a bit more exposure.

 

[MattKing]

The OM-2 metering switches from centre weighted to more of an averaging system as speeds get slower because the slower speeds do more metering off of the film surface and less metering off of the patterned reflectors on the front of the shutter curtains.
If you want to understand the metering pattern for faster speeds, you need to see the front of the curtains - not particularly easy to do without a mirror lockup function.

 

[M-88]

If you want to understand the metering pattern for faster speeds, you need to see the front of the curtains - not particularly easy to do without a mirror lockup function.

It's fairly simple if you fire the shutter without the batteries

 

[MattKing]

It's fairly simple if you fire the shutter without the batteries

Good point!

 

[ted_smith]

OK, thank you guys. Thats helpful.