underexspose or up iso

i just wondered what would be best if you were doing a shot that would be underexsposed if you set iso 100 but you will get noise if you set iso 1600 ( forget about noiseware for a min ) would it be better to shoot raw at iso 100 then process for underxsposed in rawshooter etc or set iso 1600 ? this is for an end result of a jpg.
Thanks
Rob

I would increase the ISO to get as close as I could to a properly exposed photo. If you underexpose, you will likely find that you have no detail in the shadows. You can always reduce noise in post processing but you can't create detail.

You can just try it out: make some heavily underexposed ISO 100 photos and try to correct them on the computer, and see if they look better than properly exposed ISO 1600 photos.

My guess is that ISO 1600 photos will look better than corrected heavily underexposed ISO 100 photos.

Nothing beats trying it out. I think it depends on the camera, too. I have the good old 300D, and the bumping the ISO up works up to about ISO 800, better than an underexposed image at a lower iso. 1600 and 3200 are just is too noisey for sharp pictures, especially in a low key shots.

Absolutely bump the ISO up. You will get less noise and more detail compared to underexposing and adding EC in the RAW editor.

I just recently conducted an experiment in which I tried to determine the answer to that very question. Here is what I found -
Shooting RAW gave me a much better image when underexposing about 1 stop than doing the same in JPG.

However, once we get to 2 stops underexposure, neither RAW nor JPG has any advantage - they both go to hell in a handbasket.

I did both shots at my maximum ISO which is 400.

The noise was no problem either way, because using NeatImage or Noiseware cleaned up the noise equally well.

Conclusion: When forced to underexpose, always set the ISO to max and shoot RAW. The worst that can happen is that it's no better than shooting JPG,

One more vote for raising the ISO. Even my lowly 300d will make a usable 4 X 6 print at 3200. Like Bob sez, a good exposure in the camera is the key.

Bump up ISO. Even if you shoot RAW you will increase noise when upping the exposure using software. Use noise ninja to reduce noise of 3200/1600/800 shots.

Getting exposure correct is critical to getting the best from your images.

Ditto, always shoot for the best exposure. You need color saturation and good contrast to PP any picture. Always up the ISO to achieve the best exposure, like everyone has already said underexposed means no image to work with. I use Noiseware Professional and I get great results at ISO 800 and up. I very rarely worry about noise at ISO 400 even at 8x10 print size.

I have been known to intentionally underexpose shots in the theatre, but only when I was at maximum ISO, wide-open lens, and the shutter speed would be WAY too slow to prevent blur if I exposed correctly.

Basically I would underexpose by a stop or two, just to get a usable shutter speed. I will do this only rarely, when it's very dark scene, and hope for the best. Then I would crank it up in the RAW converter. Sometimes I get something worth keeping, sometimes not.

well it seems like everyone agrees so i will use iso setting's to keep my shutterspeed high and a noise redution prog if i need to .
thanks for all reply's and help with this .
Rob.

up the iso, you can always shoot raw and have a little exposure correction as well as Neat Image for noise reduction.

Have anyone actually tested this, or is it all based on assumptions? Bob's test is a start, but isn't quite what you'd need to do to test this theory. Remember a sensor is just a photon counter, and digital exposure is just organising that information. No matter what ISO your camera is in, the same number of photos hit the sensor. The sensor and processing design might be that they work better if they're told to be more sensitive, or maybe not. This all assumes you're shooting RAW, in JPG you're screwed if you underexpose.

I'm not saying one way or another which is better, but I think experimentation is going to give you a more accurate answer than assumptions.

Yes, I've tested it, sort of (not an ISO test). I couldn't post it earlier because my web server was down, but here it is:


The image on the left was underexposed by about 2.5 stops of shutter speed, then EC added in Capture1. The image on the right was exposed correctly (3 stops higher than the left), no corrections in C1.

Here's PacAce's post. Scroll down a little to start seeing his pics. Particularly the Buddha.
https://photography-on-the.net/forum/showthre​ad.php?t=66836