Unless the article in the link I posted flawed, the ratio of bits representing photon fluctuations to the bits representing the total signal amplitude is constant for all exposures, i.e. for all signal-to-noise ratios. Reducing the S/N does not change the bit ratio.
Is the article flawed?
Is it true the ratio of bits representing photon fluctuations to the bits used for the total signal remain constant?
These articles are too technical for me. My best understanding is the diagram posted by Guillermo Luijk here:
http://www.luminous-landscape.com/forum/index.php?topic=56906.40The current thinking seems to be that Canons needlessly add noise after ISO amplification whereas Sony and others do not. Consequently, ETTR can improve the S/N for Canon; much less so for Sony. (John Sheehy was preaching the problem with Canon a decade ago on dpreview.)
My impression is that, as time goes on, manufacturers will do more re-work with software before even the raw is delivered. Those purists who hope to understand the workings of hardware so that they can optimize their quality may be increasingly frustrated. Engineers are constrained by the laws of nature; software writers are not. In their world, anything goes. Whether the results are good or bad for you may depend on your outlook.
James Russell, posting as bcooter:
'A lot of photographers raised in the digital age don't know how film looked. To them the standard look is Canon on nikon dslrs which are somewhat overly smooth and somewhat global in color. Also digital tends to pick up a great deal of ambient color. In other words a brown room makes for a brown photo, even with specific lighting. The olympus look more like film, in the fact film was kind of dumb. It saw what it saw and didn't usually pick up ambient color. Also with film, once you learned a specific film you knew how it would react regardless of setting. (That one is hard to explain but you know it when you see it).....
Now this one blows me away. i'm usually not one to say this camera costs less than that camera, but for a $1,200 camera (the em-5 I bought new) vs. a $6,000 Canon there should be a difference titled towards the higher price and in image quality there isn't, it's the other way. maybe the Canon has a fraction more noise reduction and a fraction more detail (on this I'm really not sure), but the look is not near as nice or specific . . . or film like.
Obviously olympus is on to something good, because Sony and Fuji have tried to emulate the look. I don't think they'll hit the built quality, but the looks like a camera style seems to have caught on.'
http://www.luminous-landscape.com/forum/index.php?topic=86337.msg701314#msg701314I'm guessing the film-like look and grain-like noise that James Russell and others admire is somewhat dependent on Olympus working software magic on a file that has NOT been ETTR'd. Am I mistaken? If the only downside of not using ETTR is to live with the grain-like noise of the E-M5, I'm OK. I'd even choose ISO 800 to GET that look most of the time. Just my outlook; YMMV. Everyone comes at it from a different angle. Living in the UK, we look with envy on the beautiful reflected sunlight that those in the US seem to have on tap. Those folk need ND filters; here we're struggling to achieve usable speeds. For anyone shooting a wedding here today - wet and windy - ETTR will be the least of their worries.