What using high ISO really means

Getting over my aversion to using anything over ISO 400 has meant understanding better what the implications are of using higher ISOs.

Yes, high ISOs are necessary to get shutter speeds in low light that are fast enough to prevent motion blur or camera shake.

Yes, the drawbacks to image quality when ISOs get high is that it introduces noise, decreases contrast and colors can start to get a little muddy--BUT, a properly exposed image can hide this.

What it really means is that when shooting high ISO, the margin of error is a lot smaller and the key is to ensure that it's properly exposed. More specifically, ensure it's not underexposed. When a high ISO image is underexposed and you try and lighten the shadows, the detail is usually not there, but a lot of noise is.

So, just remember for anything over ISO 400 (at least for Olympus cameras), be sure to properly expose your shot, and I even err on the side of overexposing to be doubly sure.

Here's a shot from today that I took at ISO 800. Roxy moves a lot and I needed ISO 800 to make it fast enough to try and keep it sharp. You'd have a hard time knowing that it was ISO 800 though, because it was well exposed and because so much of the photo is bokeh (the out-of-focus blur), which helps hide noise.

Olympus EP-1 @ 20mm, f1.7, 1/125 second, ISO 800,+0.7 EV.