[MrB1]

What do I gain by doing the multiplying in PP that the camera is willing to do for me?

My knowledge of these technical aspects is rather limited so, at a simple level, my understanding is that we should capture as much light as we can for each image (without blowing important highlights). In dim lighting, when there are good reasons for not further reducing shutter speed or widening the aperture, increasing the ISO brightens the image produced by the camera. However, when we are able to do this brightening in PP, we have much more control of the image because, unlike in-camera brightening (i.e. increasing the ISO value), we can selectively and differently brighten different parts of the image to our artistic intent.

Philip

[elicius]

The very definition of an Iso invariant camera is :

Analogue processing and conversion to digital signal converter--------->
Creates NO NOISE!!!!!

Iso invariance is an accepted attribute of the later Sony sensors (among others)
It is not hard to go and test the principle yourself. Just take a correctly exposed shot of a setup that requires a high Iso like 3200 and take a second shot with aperture and shutter unchanged but at Iso 100. Push the Iso 100 shot 5 stops in your raw developer and compare the results.
People should stop debating whether it exists or not but rather discuss whether it can be an important part of their processing.

A perfect ISO invariant camera does not exitst on the market yet. Though cameras and sensors have improve quite a bit so that the generated post sensor noise has become less, cupple that with an improvment in noise cancel algorithns you can get really great results just using iso 100.


Like GUB said you can do the test, but please don’t use a random RAW editor for that, a lot of raw editors like lightroom apply noise cancelling in background making the results look better then they actually are. I have tried it for myself and I can say that there is a difference.

[GUB]

Because this test required a 5 stop push I developed it in Rawtherapee because my normal developer Darktable only slides 3 stops. I am unaware of any denoising going on in the background with either.

A perfect ISO invariant camera does not exitst on the market yet.

And a perfect camera does not exist on the market yet but we happily utilise them imperfections and all -- why does Iso invariance have to be perfect before we use it ? As I have said before you get slightly different results from the two procedures - sometimes one is better than the other sometimes not.