[INVALID] Dual iso to improve low light shutter speed

[nikfreak]

Yes, I tried to search to find dupicates.
No, I couldn't try myself as I have still no cam so scratch that if it's not possible or already done.

Could dual iso be of any use to improve low light shutter speed and get a correct exposed picture after postprocessing? As I know dual iso improves DR. You have to post process the outcome to get a nice looking improved picture.

Now take this. let's assume I have no image stabilization in my lens. I have no flash or can't use it. I would have to expose let's say a picture at iso 3200 and 1/5th of a second with an attached lens. Could dual iso be of any use here? Let's say I set "low light dual iso" in camera and now I could take the shot with iso 800/3200 (or whatever) and 1/40th of a second. thi would avoid blurry image by hand shake and the outcome would be dark. But after post processing I get the same look (not HDR alike) like shot without dualiso and normal iso 3200 and 1/5th.

So using it for overriding camera values when operating in "aperture priority mode" in low light to get faster shutter speeds and postprocessing afterwards on pc. Hope you got what i am thinking of. Some might ask why not simply set iso to 6400 or anything like that. It's just an idea of myself if dual iso can be of any use in such situation.

[dmilligan]

I would have to expose let's say a picture at iso 3200 and 1/5th of a second with an attached lens. Could dual iso be of any use here? Let's say I set "low light dual iso" in camera and now I could take the shot with iso 800/3200 (or whatever) and 1/40th of a second. thi would avoid blurry image by hand shake and the outcome would be dark. But after post processing I get the same look (not HDR alike) like shot without dualiso and normal iso 3200 and 1/5th.

Nope, dual ISO cannot violate the laws of physics.

Remember that all else being equal, higher ISOs are less noisy (per electron) than lower ones (if this wasn't true, then there'd be no reason for having ISO at all, as ISO 100 would have the least amount of electronic/sensor noise). This concept is counter intuitive for a lot of people, and is the main reason ETTR is misunderstood.

ISO3200 in dual ISO mode (as the larger ISO) is not somehow magically less noisy than ISO3200 not in dual ISO.

The advantage dual ISO gives you is that you can make the base ISO (the lower ISO) less noisy via the recovery ISO (the higher ISO), but the amount of noise you're going to get is not going to be better than the recovery ISO by itself => that's impossible, where would that data come from?

It may make more sense if you think of it backwards, in terms of noise, and call the higher ISO the "base" ISO. The final output is going to have about this same amount of noise, but you're going to recover some highlights with the lower "recovery" ISO. (Note how I swapped the labeling of "recovery" and "base" ISOs).

If you're already at ISO3200 without clipping, it's better not to use dual ISO at all, you're only going to lose resolution, and make post processing harder.