Exposure basics, lesson two point one (& ISO)

Started Mar 19, 2013 | Discussions thread
OP texinwien Veteran Member • Posts: 3,326
Re: Exposure basics, lesson two point one (& ISO)

Continued from here .

bobn2 wrote:

texinwien wrote:

Interesting. Some posters think that the discrepancy between the E-M5 Camera ISO Settings and the DxO "Measured ISO" or saturation-based sensitivity measures would somehow allow Olympus to make it appear as though the E-M5 has better noise performance at any given camera ISO Setting than it actually has at that setting.

I think that's bunk. But it's a bit of an aside, anyway.

I think it's bunk also, at least if you take just that factor. However, one wonders why olympus has left so much headroom, instead of putting in a lower ISO setting that many would have appreciated. As I suggested, one good stratagem to make low light performance of a camera appear better than it really is is to make the multi-pattern metering recognise low light situations and dial in more exposure. If one were doing that, it would pay to have a bit of extra headroom.

I'm working to wrap my pea brain around the information here, so I hope you'll bear with me while I ask some questions and do a bit of reasoning out loud.

First, when you say 'dial in more exposure,' I take it to mean that the camera would lower the shutter speed. Assuming that's what you mean, is there any evidence that would suggest that the E-M5 does, indeed, do this?

Also, in your good example stratagem, the camera would be programmed to only lower the shutter speed when it recognized low light situations. With that in mind, I have a couple of questions:

What would you expect to happen in well-lit situations? I assume that you would expect to see 'correct' metering in these (correct based on the camera ISO setting).

Do you think most ISO test scenes used by DPReview, imaging-resource.com and other well-known testing outfits would count as low-light scenes in such a stratagem?

If we saw 'correct' metering in well-lit scenes (correct based on the camera ISO setting), we would see more noise in them than we would have seen had the E-M5's ISO settings been more closely aligned with its saturation sensitivity. Would you expect consumers not to notice this excess of noise in well-lit images?


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