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.
So as I referenced in an earlier post, I bit the bullet and bought a camera so I could test out CHDK. CHDK is a hacked firmware for canon cameras that use one of three imge sensors. I believe it is the digic 2, 3, and 4 sensors. It turns out that all of the powershot line uses the same image sensors. The optics, buttons and features are added or removed based on the price point of the camera. If you use CHDK you can enable them AND add new features the designers may never have thought of! click here to find a compatible camera on amazon More info about my trials and tribulations after the jump.