Re: Two cameras or one?

It depends to an extent on what you plan to do aesthetically with the footage later. Arguments can be made for both choices.

If you're counting on a lot of b-roll to cover, well, that is very, very common, and nobody would fault you for it, generally.

But what if the material you're shooting is above-average emotionally, such that you really do NOT want to break away? Doing the re-framing right in the middle of the best, never-to-be-repeated-quite-as-well line of dialog? Want to risk that? You're going to get trapped at some point, always zooming or dollying in and out to re-frame while they are talking and emoting, or imposing perhaps the wrong rhythm to the sequence between focal lengths you changed while asking questions...you'll find you got too clever for your own good and wound up with two shots that need to be back to back but now create a jump cut situation because of framing choices made when shooting. I think too many folks use cutaways more as a cheat than to reinforce the story... people who primarily cut news packages, I think, tend to do that more; tend to build in a bit too much artifice, superimposing structure on the shots before you know what they are going to be...

Most such stuff I admit, I do single camera, mainly for budget considerations, but I am working on some doc footage that will eventually go into a huge, multi-year archival project, where it will be made available for other future film makers. As a way to keep the options of such future Ken Burnses as open as possible, we're shooting all those 2-camera, side-by-side locked-down, in a tight and a medium shot.

I also do 2-camera when working with non-pro talent that are trying to dramatize a scene, and I don't have lot of time to get everything. They can't be as consistent as real actors, so everything takes longer to get right, and the only way I know I can get matching shots of the one good take out of 20 they try, inside the time limit I have, is to shoot 2-camera with coverage. (which is why actors don't always cost more, sometimes they SAVE you more) But you're talking about straight docs here, so that may not apply...

Here is something you definitely should consider, though:

Another option you may have is to shoot single camera, but in high def, which allows you to re-frame to tighter shots in post without as much noticeable loss as it would if you shot in Standard Definition.

I just played around with a situation like this in a recent commercial spot, where it was cake to tighten and re-frame such a shot that originated in 1080 with nobody the wiser. In my case, the final output was back to standard def, letterboxed, and it looked just fine that way. Nobody could tell I'd blown up one particular shot about 25 % and re-positioned it for a better match-cut. That's the benefit of more pixels to push around. You can add slow dolly moves or zooms in post where you want them, with all the time in the world to decide and keyframe exactly where they work best.

From a cash standpoint it may not be as big a jump to shoot the thing in high def if it can save you the cost of the second standard def camera, all the extra footage on tape, etc.

Hard drive space-wise, it's probably a push: you don't have two sets of images to store, but the HD does take up more space by itself. Still, hard drive space is dirt cheap now.

Just wanted to make you aware you have options you may not have thought of.