I lust after subjects that combine three things: color, light and motion. And no subject provides those three things better than a Ferris Wheel at a canival. Where else are you going to find a fifty-foot tall wheel of light that spins around in the night? (And personally, since I'm terrified of heights, I'm perfectly happy to be on the ground looking up.)
Last summer while illustrating my exposure book (Exposure Photo Workshop) I spent many days and nights wandering around carnivals with my cameras and tripods photographing all kinds of rides using a whole range of long shutter speeds. It was great fun and I got hundreds of cool shots. In fact, we ended up using a variation of the shot here as the cover of the book.
Oddly enough, I first got the idea to use long exposures with carnival rides when I was a teenager. A policeman who was working at a carnival where I'd gone to take some snapshots saw my tripod and asked what shutter speed I was using. Innocently I told him I was shooting what the meter told me to, usually 1/30 or 1/15 second. He told me to put the shutter speed dial on "B" (bulb) and leave the shutter open for 10 or 15 seconds--so I tried it. Turns out he was a serious amateur photographer and had done a lot of time-exposure shots. When I saw the slides (this was 30 years before digital) a few days later, I was blown away! The photos were just big rich circles of color and they were the wildest shots I'd ever seen. I couldn't wait for more carnivals to come to town--and I shot every one that did.
There are no hard rules about how long to expose for and I experiment with exposure ranging from 1/2 second to 30 seconds (a lot depends on the speed of the wheel, too). I just put the camera in manual, set a small aperture (say f/16 or f/22) to keep everything sharp and to give me a range of long shutter speed options, then bracket widely with shutter speeds. Don't speed up your ISO or you'll introduce too much noise; I leave my camera set at ISO 200 since I'm ignoring the meter anyway (again, I bracket based on what I see on the LCD).
Look at your results as you're going along and you'll know which exposures are the most interesting. And change lenses (for the shot here I zoomed in to just take the center of the wheel) or your shooting position every 10 or 20 shots so you're not just locking in to one composition. I often shoot from a half dozen different positions just to be sure I'm getting the most creative angle.
Beautiful San Francisco
10 hours ago