The Digital Photography Book

When to Use Super-Fast Lenses

If you want to shoot indoors without using flash (like in a church, museum, theater, or anywhere flash and/or tripods aren’t allowed), then you need a really fast lens (which just means a lens whose f-stop goes to a very low number, like f/2.8, f/1.8, or f/1.4. The lower the number, the lower light you’ll be able to shoot in without using a tripod). Here’s why this is so crucial: when you shoot in a dark place, the only way your camera can make a photograph is to slow down your shutter speed, so more light makes its way into your camera. That’s not a problem if your camera is mounted on a tripod, because it’s perfectly ...