Noise: High ISO vs Underexposed

Hey guys, been receiving different answers from photographers in my area regarding my question.

Is it better to shoot with high ISO vs underexposed low ISO (but exposure increased in LR/PS which introduces noise)? Both will introduce tons of noise but does one method have less noise/better quality than the other?

For example: I can shoot a low lit area with ISO 800 and proper exposure. However, I can also shoot at ISO 100 and then bump the exposure up in LR/PS by 3 stops.

I'm guessing better to shoot with high ISO so it's less work in post?

Use the ISO needed to properly expose in-camera. A well-exposed ISO 800 shot is going to look way better than an underexposed ISO 100 shot pushed 3 stops.

Proper exposure at a sufficiently high ISO is much better than underexposed lower ISO...maintaining better signal-to-noise.

Expose correctly. Do not underexpose.

Anybody that say underexpose is simply wrong.

Do yourself a favor, spend an hour and set up a test shoot with a tripod and take some images. Use only full stop ISO and shoot RAW.

i think there is a difference between ISO 800 and "high" ISO. I consider high ISO something like 6400 or more (maybe ISO 3200).

I think in almost all cases it would be better to expose properly, but if you're using really high ISOs (ones that aren't "real" ISOs for the camera), then it might not matter if you underexpose and push it in post since that's what the camera is doing anyway.

Expose properly from the camera using native ISO settings, even if you need the cameras maximum ISO setting. Pushing in post processing does not result in cleaner images. It results in noisier images and to make things worse, the colours of pushed images get thrown off. Because of the colour issue i dont like to even do the opposite which is over expose and pull down in pp. It will result in less noise but the colours will take a jump.

With my 20D which maxes out at H=3200 ISO I would rather shoot at 3200 and ETTR so that I can pull down a stop in post (Shooting RAW) than shoot at 1600 ISO and chance it needing a bit of a push in the shadows. I would also rather ETTR at ISO 800 than have to push ISO 100 by one stop in post. Actually I find that even pushing exposure by half a stop at ISO 100 will start to show noise in shadow detail that won't be there when I shoot ETTR at 800. Of course if I can I would still rather shoot ETTR at ISO 100, as that will give me the best starting point.

Personally I will always expose for the shadows, while not blowing the needed highlights. Specular reflections, well they can blow right out, but then they would have no detail anyway would they.

Alan

BigAl007 wrote in post #14939076
With my 20D which maxes out at H=3200 ISO I would rather shoot at 3200 and ETTR so that I can pull down a stop in post (Shooting RAW) than shoot at 1600 ISO and chance it needing a bit of a push in the shadows.

Expanded ISO's are already doing that in camera.

Use whatever ISO is needed, don't try tricks you read about as rumours. Expose as accurately as you can, with your white balance set properly (it changes the histogram), and watch the histogram.

tim wrote in post #14939309
with your white balance set properly

This makes a huge difference.

Read this:

http://wwwimages.adobe​.com …hop/pdfs/linear​_gamma.pdf

Never intentionally underexpose. There is something to be said for overexposing, though. My 1D III jumps from 3200 ISO to 6400 ISO with nothing in between, so if I can get away with it I'll overexpose a bit using the shutter speed I need to take the picture but not the highest shutter speed I could use to get an even exposure at that ISO. The end result is when that when I pull back in post, I'm actually shooting at 4500 ISO or something along those lines. It's called expose-to-the-right and there's a long post about it somewhere on the forum. (I do also know that 1D III is just pushing a 3200 ISO shot one stop to make 6400 ISO, just wanted to head off the 10 people who would have told me that).

windpig wrote in post #14939133
Expanded ISO's are already doing that in camera.

I know this but still find the result to be a bit better than the other option. At least that is my perception of what works for me.

Alan