Is ISO 200 still considered to be a bad choice, on digital cameras?

Question

In times of film photography there was a rule to either use ISO 100 film (or even great Velvia 50) which usually had considerably less grain noise than ISO 400 film. So 100 for outside or well lit subjects and 400 for indoor everyday photography. It was also considered that ISO 200 film was a bad choice because it provided no obvious advantage over 400. It had more noise than 100 and was slower than 400.

What's up with ISO 200 these days on a digital camera? Can same rules with 100 and 400 still be applied to DSLRs or have times changed considerably and nowadays even 200 gets used lots?

Disadvantagaes/advantages in terms of colours, contrast, noise and any other factors. What ISO settings do you usually use?

And I'm talking here about cropped sensor DSLRs (Canon and Nikon brethren).

Answer

I think it's still generally true that one tends to either use lowest-possible ISO in bright lighting, or else higher-than-200 ISO settings in darker situations. But I wouldn't say I'd avoid ISO 200; it just often doesn't seem to be convenient. If I'm in the sun, there's usually no need for it, and if I'm indoors, I'd often rather get a little more depth of field or a faster shutter speed than worry about keeping ISO down. But if ISO 200 fit the exposure and aperture+time I want, I'd not think twice about using it.

One reason is that changing ISO is trivial now; I can choose ISO 200 for a particular shot with the press of a button and flick of a dial (or going into a menu), rather than committing to it until I change film. I can even let the camera automatically use it whenever it fits best.

Another other consideration is that modern digital SLR cameras, especially of recent vintage, have really very good high-ISO capabilities. The noise might not be attractive as film grain sometimes can be, but there's much, much less of it. So rather than going to ISO 400, one might not think twice about ISO 800, 1600, or beyond. I think you're right, though, that ISO 200 is still left in an awkward spot — if ISO 1600 looks great, why not use that instead?

On some cameras, though, there is a reason where ISO 200 is actually technically preferred over ISO 100. This is because on these cameras the base iso of the sensor is 200, and going below that is actually worse, since it reduces dynamic range.

Or, one might want to use a highlight-preserving mode, if you camera offers it. Because digital sensors clip highlights in an ugly way rather than the graceful analog response of film, having blown-out bright areas is particularly bad. Some cameras offer a mode where they actually underexpose by one stop and the adjust upwards — you get more protection for highlights at the cost of increased shadow noise. And since each shot is really exposed one ISO step down, the bottom of the scale — ISO 100, on my camera — isn't an option. So, when I turn that on, ISO 200 becomes the lowest setting.

So, overall: I don't think there's a special problem with ISO 200, but I do think it tends to fall kind of in a less-used middle point. If you're using a camera which, for technical reasons, makes ISO 200 a good choice, don't be afraid of it. If you're using a small-sensor point & shoot camera where ISO 200 is worse than 400, there may be times when it makes a good compromise setting, but on cameras which exhibit less noise at higher levels, you'll probably just use those instead.

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