As I mentioned in my previous post about controlling the 5D Mark II’s shutter speed for video, it seems that the auto metering likes to use a shutter speed that is 1/focal length. It turns out that you can also exploit this behavior to get some control of the aperture.



If a scene is too bright, the 5D Mark II will stop down the lens before it drops the shutter speed below 1/focal length. So if you are working with a zoom lens, you can force a smaller aperture by zooming to a longer focal length until the camera picks your desired aperture. Then lock the exposure with * and zoom back to the actual focal length you want to use.

There’s been much gnashing of teeth over the fact that Canon has limited the 5D Mark II’s video mode by not providing manual controls for ISO, shutter speed and aperture. I’m new to the whole video thing, but from what I’ve read so far, controlling shutter speed is especially important to people that want a film-like look. Apparently this is because motion picture cameras normally employ a 180 degree shutter, which means that the shutter speed is double the frame rate. Since film normally runs at 24 frames per second (fps), it uses a 1/48 second shutter speed. The 5D Mark II runs at 30 fps, so we don’t want it using anything slower than 1/60 of a second.



Here’s the trick: It seems that Canon’s auto exposure algorithm prefers to use a shutter speed that is 1/focal length of the lens. So if you’re using a zoom lens like the 24-70mm, you can set the lens at 60mm to give you a 1/60 shutter speed, lock the exposure using the * button and then zoom in or out as you please.



The lighting of the scene seems to exert some influence on the shutter speed, so you’ll need to zoom in and out around the 60mm length until you find a spot that forces 1/60. You can check this by half-pressing the shutter button, which will cause the camera to display it’s chosen shutter speed, aperture and ISO at the bottom of the LCD screen.



I just received my camera today, so hopefully I’ll have more insights to post over the coming weeks.



Update: Please note that the displayed values will still change after the exposure is locked. The user manual says that these are the values that will be used if a still photo is taken, but supposedly the exposure for video will remain at the locked settings. It sure would be nice if the camera would keep the video settings displayed. Of course, manual exposure settings would be even better…

My new Canon 5D Mark II arrived today. So far I’ve only had time to unbox it and play around a little. I’m planning to post some first impressions later tonight, and then I’ll be working on some review posts as I get to know the camera. In addition to talking about how it handles as a still camera, I’m going to take a look at the new video functionality that everyone’s so excited about.



In the meantime, here’s my original post about why I decided to sell the 1Ds Mark III and switch to the 5D Mark II.