Auto ISO or Manual ISO?

[carlthuringer]

I'm using a Canon Powershot S3 IS and I just started thinking about ISO.

Unfortunately when reading online I couldn't (in about 30 minutes) find a definitive answer or even a decent explanation of techniques or strategies involving either auto or manual iso. About all I spotted was some photography seminar-giver's crazy rant about how everybody should take every shot in auto and just correct the exposure compensation.

So anyways... What do you DPS folks like to do? Take shots at a preferred ISO and compensate with a tripod, flash, or powerful lighting or set to auto ISO or high ISO and instead focus on Tv or Ap modes?

Or something else altogether?

[Nicole]

I currently set my ISO to 200 and compensate with manual mode so that I can set my shutter speed and aperture to the way I want it (slightly underexposed to compensate for the d50 liking to overexpose things). Of course I also use flash and tripod depending on the situation, but I like to keep my ISO low. So, if you don't want to use manual settings, I'd say use the Tv or Ap modes on your camera.

I really don't like the idea of correcting the exposure compensation because the worst thing about using a high ISO is the noise. I had a picture I took around dusk out by the ocean, with really calm colours, and it was basically ruined by noise. Granted, it wasn't anything fantastic, but I liked it, or I would've if it hadn't looked so noisy.

This page on Exposure Strategies for Digital Cameras has a bit to read about ISO on it and had this to say:

Using ISO Wisely

Controlling exposure by manipulating ISO in lieu of aperture or shutter speed is generally a bad idea because higher ISO settings beget more image noise, as we've just seen. But ISO adjustments are often inescapable in stop-action work, where short exposures and low available light are a common mix.
The increased noise isn't always subtle, but if a higher ISO makes a must-have shot possible, the noise may well be a price worth paying. Image noise tends to be more apparent in the shadows (which may be expendable) and at higher final magnifications, like the ones needed for 8x10 prints (which may not be needed). With forethought and extra exposures specifically designed for the purpose, you can significantly mitigate noise in post-processing in relatively static scenes like the night sky sans moon, but such subtraction and averaging techniques aren't applicable to the short exposures needed for stop-action work, where need to bump ISO issue most often arises.

[carlthuringer]

I myself have had times where because of low light the camera selected ISO 200, 400, or even 800 (if I left it on Hi ISO mode) and really been disappointed when I later offloaded the pictures to the PC for review.

Furthermore, the particular camera, the Canon Powershot S3, is a Prosumer or Super-zoom type that, despite its weight and feature-heavy setup is still hobbled by a small sensor which, to my understanding, introduces more noise to the image. I'm tempted to leave it at ISO 80 or 100.

But as for noise, I've recently discovered Noise Ninja and that helps alleviate a lot of ISO 800 headaches. (where one might as well have taken the picture through a confetti factory explosion)

[Nicole]

Originally Posted by carlthuringer

But as for noise, I've recently discovered Noise Ninja and that helps alleviate a lot of ISO 800 headaches. (where one might as well have taken the picture through a confetti factory explosion)

I don't have anything more to add other than the fact that I love that analogy!

[Triglav]

Noise Ninja doe a good job, but be careful not to overuse it! It is a real pixeldestroyer.

As for the ISO question: there are three things that you can use to get the light right: aperture, shutter speed and ISO. I have learned that you should use aperture and shutter speed to get it right and only raise the ISO value if there is too little light to handle with aperture and shutter speed.

And then again..you can use a very high ISO value for creative reasons..

[hsroxas]

Just to share my own preference, as I think Nicole explanations pretty much covered the nuances of ISO and noise. Looks to me also that you have a very good appreciation of the relationship among a small sensor,ISO, and noise.
I am using both a DSLR and a compact, both of which are Canon. On my compact I seldom go beyond ISO 100, at most 200 but with my DSLR I can get usable images even at higher ISO settings. So I shoot mostly using the base ISO of my camera. Where flash is necessary and allowed, I use flash. But when I want to capture the mood of the lighting (no flash), I use the largest lens opening I have and only adjust ISO if the setting is still not enough to take the shot. Just like what you use, I enjoy a small advantage on shutter speeds as I use mostly IS lenses only. To me, I don't use AV or TV to compensate. I use AV when I want to control depth of field and TV to stop action or create motion. Hope this addresses your point.