ISOless sensors, read noise and photography - many questions!

Started Oct 3, 2013 | Discussions thread
OP boardsy Senior Member • Posts: 2,215
Re: full circle: "just raise ISO, when necessary!"

Steen Bay wrote:

boardsy wrote:

Steen Bay wrote:

bobn2 wrote:

boardsy wrote:


- no visible benefit in keeping ISO at the low read noise minimum (800 for this sensor), and possibly struggling with a dim view/LCD in camera, and raising brightness later.

I'd be very interested if bobn2, Great Bustard, Gollywop, Detail Man et al would agree?

It depends on the scene. If the scene has a higher tonal range than can be handled by the 'correct' ISO, then there is advantage to using the lower ISO.

Could be argued that the ISO isn't 'correct' if important highlights are blown. Then the 'correct' ISO would be a lower ISO where the highlights are protected.

@ bobn2 - yes, that's been mentioned already, and part of what I assumed by "when necessary" - so raise ISO as required for a bright image with protected highlights (if they're a priority for the shot - better-exposed shadows could be more important). But aside from protecting highlights it seems here's no other benefit to keeping it low and raising brightness in RAW later.

@ Steen Bay - isn't that pretty much what bobn2 is saying here? I.e. if the EV=0 suggests a high ISO ('correct' ISO according to the metering) that blows a few highlights, the 'really correct' ISO should be lower (if highlights are a priority for the shot - better-exposed shadows could be more important).

Using a lower ISO in order to protect the highlights won't affect the shadow noise if the actual exposure (f-stop, shutter speed and lighting) is the same.

Yes, of course! (Unless ISO is part of exp... Sorry, unless ISO is being used to influence aperture or shutter speed.)

But yes, think we agree here. No need to use an ISO that's so high that important highlights are blown, and no need either to use an ISO that's so low that the highlights are e.g. 3 stops below the clipping point (which would give unnecessarily dark JPEGs).

Yes - I'd thought in the wake of the ISO wars that under-exposing when necessary, keeping ISO to a minimum best read noise level (likely 200/400/800) and raising brightness in RAW was somehow preferable to high ISO wrt noise, but it doesn't seem so, not for the NEX sensor anyhow.

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