Exposure basics, lesson two point one (& ISO)

Started Mar 19, 2013 | Discussions thread
texinwien
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Re: Exposure basics, lesson two point one (& ISO)
In reply to texinwien, Mar 19, 2013

Continued from here.

Could you clarify a couple of points for me?

Jack Hogan 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.

Yes, I have read the same thing many times.

I believe you have also agreed with that thing on at least one occasion. Would you say that you agree with that thing right now?

It appears that if one wanted to capture the very same tonal range from a scene with the EM5 and the G3, same exposure and all, one would have to set the EM5 at in-camera ISO 3200 while the G3 at in-camera ISO 1600, with roughly similar resulting SNR (EM5 slightly better as per DxO).

I'm following your example, so far.

On the other hand, if one set both at 3200 maintaining the same exposure they would no longer be directly comparable, but the G3 would appear noisier to a naive observer.

Would it appear noisier, and would the observer be naive to believe what he saw? If by 'maintaining the same exposure' you mean that the scene luminance, shutter speeds and f-stops were kept the same on both cameras as in the first example, the G3 would get exactly one additional EV of exposure, compared to the exposure it received in our first example, whereas the E-M5 would get the exact same amount of exposure as in our first example.

How will this fact affect the amount of noise in the final images?
What effect does bobn2's statement that "the bigger exposure will win" have in scenario #2, or does it have any effect at all?

tex

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