We used a Sony V1U for collecting most of our footage during the doc shoots, and it's a great camera. As always it's up to the operator to get the most out of a scene. For sure though there are some real disadvantages with using a cam that has a 1/4 inch chip. I could also go on for hours about the issues of of dealing with the 8 bit 4:2:0 chroma subsampling which makes color keying potentially problematic, not to mention very limited dynamic range. But for many sit down interviews, the built-in lens and the small chip size are issues in terms of what's in focus and what isn't. This is very important in controlling where the viewer's attention goes. Coupled to this is the background brightness, particularly when you have to run an interview in less than ideal locations. There are adapters that screw to the lens and allow you to attach a 35mm camera prime lens, but we don't have one of these and there would still be the issue of controlling background brightness.

The sit down interview with Floyd Hamilton, who was the production coordinator on Day of the Wolves (he was also in the roles of chauffeur and pilot, but if you blink while watching the movie, you'll miss that).He's a great guy and any success that the doc has will be in no small part due to his help. We filmed him driving around Lake Havasu in May of '07. Looking at the footage afterwards, it was clear that Floyd was a central figure in the story. I wanted a further sit down interview with him, but by that time he was out of town but offered the opportunity to visit with him which I accepted. There was no electricity that I could use for basic lighting and it looked like it would be an outdoor interview, which I find challenging. A major problem shooting out of doors is controlling background brightness. OB units will often use something like a a Scrim Jim to hold netting placed behind the interviewee that drops the background brightness one or more stops. I didn't have the luxury of a Scrim Jim or focus adapter, so I've needed to perform a lot of work in post on many of the interviews to bring them up to snuff.

In essence, the work has been to isolate the interviewee from the background, process the background and then place them back over it a convincing way. This is pretty basic compositing work, but tedious none-the-less, and I used Apple Shake for most of this work. If anyone wants a more detailed explanation, holler; but the steps were:

1. Check to see which parts of the interviewee can be easily isolated from the environment using luma or color keying (in the case of 4:2:0 color sampling on HVDV material, luma keying potentially provides better edge definition). Image 1 below shows the interview scene and there are a couple of areas (such as parts of Floyd's hat) which I keyed from. Much of the rest is roto'd, and if you look at the trailer, you can see this since the roto was done in Shake for speed (Shake roto really sucks) and it was done quickly for the trailer.
2. As a last resort, use rotoscoping to isolate areas of the interviewee that can't be keyed.
3. Once you've successfully isolated the subject, create a clean plate from a frame in the scene. The camera is locked off and the subject was pretty much static, so any frame will do. It doesn't need to be a 100% clean frame, just make sure that the edges are cleaned away. The reason for this is that we will later apply a defocus to the background. If we don't eat into Floyd's element in the background, it will cause a dark halo around the foreground element. We use the matte derived from the foreground element to insert the clean plate into the background.
4. We now apply a defocus to the background, but we want this to look realistic, i.e. things closer to Floyd appear more in focus than those further away. To achieve this I added Z-channel information to the background via an appropriately angled color ramp. This was fed into a z-defocus node and voilla
5. The final step was to use an edge matte to blend Floyd in with the background
6. A further step is to regrain the background, since it's averaged out by the blurring, but for the small trailer this wasn't necessary.

And there you have it; I think the difference is pretty noticeable. We were able to both defocus the background, change it's levels and color balance in post. Is that recommended? Probably not, but the take home message is that you shouldn't give up on a shoot if it's not turned out exactly how you would have liked it to. There's plenty that can be done in post.

Image 1: Unaltered image with a distracting, in focus and bright background

image 2: Shake setup (how *not* to order nodes!!!)

image 3: Creating the background. a: background with clean plate mapped in. b: gamma/color adjusted background. c: background with defocus node. d: defocused background with Z-channel mapping

Image 4: Finished comp used edge matte