Light gathering in M43 vs FF

Started Nov 25, 2012 | Discussions thread
Anders W Forum Pro • Posts: 21,466
Re: Tell me, Peng, what is the difference...

noirdesir wrote:

Anders W wrote:

Does that really mean you never use the ISO dial? Well, if you have an "ISO-less" sensor (is it a D800 you use right now?), I can perhaps understand that.

I have a D800 as well (and before that a D3 which was ISOless from ISO 1600 onwards). I do use the ISO dial but conservatively, ie, if in doubt select a lower ISO but I do use the camera a lot in manual mode which means the ISO is set to have a highlight buffer and not to get a desired output brightness.

With the D800, I can see the point of staying at base ISO all the time since the sensor is virtually ISO-less and the 14-bit ADC would pretty much take care of the quantization issue I mentioned (if it is at all an issue).

One other thing I have been thinking of without having arrived at a clear conclusion yet is whether you are actually losing a bit of IQ by not cranking up the ISO even on "ISO-less" cameras. Provided that we are talking analog gain, as we do with the E-M5, you obviously get more bits to represent the brightness range if you go to higher ISOs. While those extra bits will primarily represent noise, there will be less quantization errors in the noise distribution (i.e., that distribution will be more continuous) than would otherwise be the case.

Emil Martinec has done such tests as well (and shown them here) and found no visible difference (but that probably was with 14-bit files).

That's interesting. Do you have a link?

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