Autofocus and Video

[Lloyd Ubshura]

At the risk of sounding dumb, is there a way to have autofocus stay on and constantly adjusting like a regular video camera? I'm always having to push the AF button to get a focus. Am I missing something, or is this the way it is?

[Mike Dulay]

Not for the 7D or 5D. Unlike the GH1 the AF isn't really practical for continuous focus. You can either focus manually or follow the subject so you stay in focus. The AF on EF lenses weren't designed for video. You'll notice that pressing AF-on changes the exposure and goes blurs in and out before settling.

[Lloyd Ubshura]

Oh boy... Well, since I have the camera now, I guess I just need to get used to it. :)

[Pat Munoz]

lol - I'm actually very used to manual focus on the 7D. Only way 2 go IMO! :-)

[Matt Newcomb]

I've never used auto focus on a video camera, so it's not such a big deal for me. Like anything, it has its strengths and weaknesses.

[Lloyd Ubshura]

Sorry for being so dumb, but if you can't auto focus, how do you get dolly/push shots where the camera (not zoom) is moving toward/away from the subject? Manual focus the whole thing?

[Jon Fairhurst]

You betcha.

Magic Lantern on the 5D2 allows e-Rack focus. You can set start and end points and the desired time. It works pretty well for simple stuff. It can even toggle between the two points for scenes where you are throwing the dialog back and forth.

[Richard Gooderick]

Originally Posted by Mike Dulay

Not for the 7D or 5D. Unlike the GH1 the AF isn't really practical for continuous focus. You can either focus manually or follow the subject so you stay in focus. The AF on EF lenses weren't designed for video. You'll notice that pressing AF-on changes the exposure and goes blurs in and out before settling.

Agreed. It does do this.
But it's still useful if you use it before recording the material you want.
I often use AF when setting a shot up. It's quick but not always accurate.
Manual is best (using the x5 or x10 magnification) if you have the time.

[Lloyd Ubshura]

Wow! I guess now I will have to learn how to focus and not rely on my autofocus like my A1s. I suppose, though, that once mastered, that will take me to the next level and make me not be so lazy/sloppy.

I know there is no Magic Lantern for 7D (right?), but is there anything else that will help one be able to focus better? Something like this? http://store.zacuto.com/images/P/Z-FF-1FR.jpg I can't seem to keep my focus smooth and I'm always going past my point.

[Mike Dulay]

The only dumb question is the one you don't ask. Some of us who made the leap from camcorders to VDSLRs had the intermediate step of using 35mm adapters. The lenses for these were all manual control for focus and aperture. The image was upside down unless you flipped your LCD or installed a prism/mirror. Most people stuck to primes because anything more than f2.8 (most zooms) lost so much light. Image Stabilization in camera did not translate to the lens. And since there was no way to power the lens on our adapters, SLR IS wasn't usable (same case if you use a Canon EOS to Nikon F adapter).

We learned to give up on so many camcorder advancements. Part of the fun was applying some creativity to your shots. And, for me, a lot of my shots did poorly when shooting camcorder style.

VDSLRs open things up. We don't automatically lose light from the lens. The sensors are bigger so it makes even brighter images. The image isn't flipped so composition isn't harder. But there are still things from camcorders we give up.

Some adjustments in mindset that may help:
1) Stabilization - You have many choices, the tripod is your foundation. But when you're handheld there are lenses with IS in lens. Not all of them, most primes don't, have this feature. So to work around this some use other means of stabilization like the neckstrap trick, shoulder braces & steadicams.

2) Noise - A VDSLR was primarily designed to take still photos. Many AF and IS could be picked up on the onboard mic. What's quiet enough not to scare away the critter you're shooting might not be so for the video recorder. With camcorders we complain when the onboard mic an hear motor whine (tape, zoom) because it ruins our audio. To work around that you could move the mic away from the lens and the body. That might mean a long pole (has its own issues), wireless or separate audio recording. On the 7D we have the curveball of AGC being on.

3) Autofocus - 35mm adapters were sometimes called DOF adapters. If you wanted to separate the subject from the background/foreground this was the way to go. If you wanted deep focus you could take off the adapter to use your camcorder naked. For video the sensors were small so they're naturally deep focus. Which is also good because when you're tracking something you'd like to have some leeway if the subject moves a few inches to a few feet. For stills, you could shoot 8fps and throw away half the shots that were blurry. For video, your audience might complain about your choice of effects. When 35mm adapters married shallow DOF with 24-60fps shots you ran into a wall. A face shot with 50mm at f1.8 might have the eyes out of focus when the actor moves his head. Because the lens had no communication with the camera, you were the autofocus. You learn to "rack focus" by hand. It's not comforting to a beginner, but over time it becomes intuitive to adjust your lens focus at various apertures and the distance to the subject. A high resolution monitor helps. Focus marks and staging the shot helps too.

On modern camcorders with face detect live view the AF would quietly and smoothly shift focus. The hardware and software was built with video in mind. The AF button on our 7D is made to shoot stills. Like mentioned before, noise is a secondary consideration. My sigma and tokina can be heard clear across the room when the AF-on button is pressed. When it focus hunts it also manipulates the aperture before settling down.

4) Ergonomics - the 7D's button layout, as told on the web, is better than previous DSLRs for videos. All fine and well. But its not camcorder, not that all camcorders are great. It's like the difference between a sedan and a pickup. You can tie a mattress on a sedan roof but it's probably more secure in a truck bed. When all you have is a sedan you learn its limitations and use it to accomplish what you want.