The other night I was out filming traffic. I ended up getting a really weird camera artifact. It looks like a dark bar that rolls through the shot from bottom to top. At first it made me freak out a bit, thinking that the camera was somehow broken. I eventually figured out that it is the result of A) a flickering light source and B) the right (wrong) shutter speed. I think the streetlights were tungsten bulbs, but they may have been HID bulbs. Whatever they were they definitely had a flicker to them.
I read somewhere that ideally you should shoot a shutter speed that is double the frame rate. This gives you a 180 degree shutter and it should look very similar to film. The way that I made these bars appear was by changing the shutter speed away from 1/125 when I was shooting 720p60. I have ideas as to why this creates the banding, but they are all theories. If you have any more insight pleas tell me in the comments! Moral of the story: keep the shutter speed at twice the frames per second. Change the aperture, or buy a faster lens!
I can only hope that there will be a lot of other happy people unwrapping new cameras this christmas. I bought my 7d about a month ago, and the best/worst thing is that now I realize buying it is just the beginning. I want to buy sooo much gear to use with it, and it is tough to find well recommended, modestly priced gear. Here is the short list of what I have or want to buy, to wet your creative whistle.
bogen tripod with fluid head.
If you buy nothing else on this list, get a tripod and a fluid head. The 5d/7d do not have ANY image stabilization capabilities, so if you plan on using any lens longer than a 50 you will need to use a tripod. The fluid head is also critical because many other types of heads are built for still photos. They are easily adjustable, but not in smooth movements. A fluid head is designed for video, and is the only real way to get a smooth pan.
There were a few different stages of excitement that I went through after getting my Canon 7d. First I played around with all of my manual nikon lenses (using an adapter of course). Next I marveled at the settings and the live view feature. Finally I decided I wanted to go out and shoot some slow motion video. This is fairly easy to do seeing as the camera shoots both 720p and ntsc at 60 frames a second. The software side of slowing things down required some thinking, but it’s easy once you get the hang of it.
Here is what I (and the wisdom of the internet) have come up with.