I don’t really want to get into ISO. At least, I don’t really want to get too far in to the technical details. Effects, yes. Science, no. Want some details? Check out wikipedia. Or, as I originally learned it: read The Negative by Ansel Adams (be warned, it’s not for everyone & certainly not appropriate for you if you’re only using a point-and-shoot digital camera – but if you’re ever going to get into film, it’s gold).
OK, so how does ISO effect your end result? Noise. It adds photographic noise. The dimpled effect in photos when you zoom in & see incomplete data. As a general rule of thumb, the lower the ISO, the less noise. However, the lower the noise the slower the photograph. Remember in yesterday’s post how I mentioned that you can’t control shutter speed on this guy? Well, the lower the ISO, the slower the shutter speed, and the blurrier things get.
So the real-life rule: you want to use as low an ISO as possible for the given amount of light. Rough examples that I use:
- Outdoors, sunny (or even cloudy) day: ISO 50.
- Indoors, daytime, sunny or cloudy with shades open: ISO 100.
- Indoors, shades closed during the day, but with bleed-through: ISO 200.
- Outdoors, dusk: ISO 200 (I’ll often start at ISO 100, though).
- Indoors, night: ISO 200 (sometimes have to go to ISO 400).
- Indoors or outdoors, From October through March, anytime that’s not between 10am and 3pm: 200 ISO, often dropping to 400.
Notice how I only go to ISO 400 when I’m out of options? That’s because I don’t usually carry a tripod with me when I’m using this camera. I almost always have the flash disabled, so I need all the speed I can get.
ISO 400 is the fastest this camera can go. It’s not too bad, but in low light (think normal indoor light at night) it gets pretty noisy. This varies from camera to camera, mind you: my SLR does fine up to ISO 800, then spits out pretty nasty garbage.
To get to the ISO menu? First, set the dial to “M” (for “manual”!). then click the “FUNC” button – look to the right for a display (click for a larger view). Now, use the buttons around the FUNC button to move down to ISO, then left & right to set it where you want.