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OM-5 Extended ISO Question...

David

Member
I typically have my OM-5 set at ISO 200 but I recently decided to allow it to adjust the ISO automatically. I set the upper limit at 800 (not very high I know). I noticed that outdoors on a sunny day, the ISO dropped to 64. I was using Program mode so it chose the largest aperture for the lens which was f/4. The shutter speed was 1/8000 and so it appears that to get the correct exposure it had to drop the ISO.

My question is this, is there any detrement to using, or allowing the camera to set, that low extended ISO? I've not had a chance to shoot again with those same conditions so I'm not able to analyze the quality of photos it might produce. So until I can, I thought I'd ask the experts here.

Thanks.
 
No not as far as I've noticed. I've tried texperiementing with both extremes of the ISO range, nothing unexpected happens...
 
Technically you lose a bit of dynamic range when you move to those lower ISOs, but in a lot of circumstances you might not notice it. 1/8000 is the fastest the mechanical shutter can move, but if you switch to electronic (silent) shutter it can go much faster, and the ISO probably won't have to drop. Specs say the OM-5 can do 1/32000 with electronic shutter.
 
I typically have my OM-5 set at ISO 200 but I recently decided to allow it to adjust the ISO automatically. I set the upper limit at 800 (not very high I know). I noticed that outdoors on a sunny day, the ISO dropped to 64. I was using Program mode so it chose the largest aperture for the lens which was f/4. The shutter speed was 1/8000 and so it appears that to get the correct exposure it had to drop the ISO.
As Will Rose mentioned, you hit the limit of the mechanical shutter which forced the camera to push ISO lower (64) in this case. If you want to avoid extended low ISO, you can always switch to electronic shutter if your subject/environment allows.
My question is this, is there any detrement to using, or allowing the camera to set, that low extended ISO? I've not had a chance to shoot again with those same conditions so I'm not able to analyze the quality of photos it might produce. So until I can, I thought I'd ask the experts here.

Thanks.
The extended low ISO shifts your dynamic range toward the shadows which will appear cleaner. This comes at the expense of highlights which may become unrecoverable. To what extent this impacts your final image depends on your goals.

In general, I use ISO 64 and ISO 80 frequently for motocross which produces beautiful JPG's straight out of camera.
Examples: FOX-RACEWAY-PALA
 
@Will Rose & @MEDISN : I'm not trying to avoid the low extended ISO. My question is about what bad effects might result.

Regarding blown highlights, couldn't I spot meter on a highlight (underexposing the shadows) and then boost the shadows in post?
 
I'm not trying to avoid the low extended ISO. My question is about what bad effects might result.

Regarding blown highlights, couldn't I spot meter on a highlight (underexposing the shadows) and then boost the shadows in post?
Absolutely. You can change the camera metering method or adjust exposure compensation (EC) to whatever protects relevant highlights. I believe adjusting EC in P mode (your previous example) would just close down your aperture (e.g. from f/4 to f/5.6). If you want a little more control you might try A/S/M modes.

Some cameras offer "extended" setting for mechanical shutter which automatically switches to electronic shutter when speeds require faster than 1/8000s. To my knowledge, the OM5 does not do this. Although there is little penalty for just keeping in electronic shutter all the time. Don't have to worry about shutter shock and you get faster burst rates for action. The downside is, some light sources like LED's will flicker and cause banding at certain shutter speeds. Distortion might be an issue for things like round balls and round wheels moving across the scene. I probably shoot electronic shutter 99% of the time now.
 
You can recover some highlights (or shadows) by post processing as MEDISN suggests. But it still suboptimal. You will be able to recover MORE of those highlights and shadows with less noise if you increase the shutter speed and stick to ISO 200 because ISO 200 provides more dynamic range. The only reason for using ISO 64 instead of 200 in the case you describe is if a shutter faster than 1/8000 or using E-shutter would cause some additional problem. Dynamic range is probably the biggest limitation of modern digital cameras, so it benefits you to maximize it.

If you have to use mechanical shutter, then you could go to low ISOs, or you could put a ND filter on the lens.
 
I suspect the delta in DR between ISO 200 and 64 is negligible. For the EM1.3 (same sensor), P2P gives a PDR of 9.74 for ISO 64 and 9.74 for ISO 200. It's a matter of where you want to shift the available DR - toward highlights or toward shadows. As Olympus historically has been overly protective of highlights, I have no issue shifting DR toward the shadows. No different than ETTR really with the added benefit that image lightness is closer to what I want in the end.
 
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