So, as I had invested in a Canon 550D last year, I thought I would take advantage of it for my film project. I've been experimenting with the film settings on it since I purchased it, but this was the first time I had the opportunity to test it in the green screen studio. All my footage this term so far has been filmed on my 550D, and each time I have run into issues.
First off, for green screen work, particularly when tracking, it is important to have a crisp image with high depth of field. One MUST have the subject and the track markers in focus or tracking becomes a nightmare. After some reading, I discovered increasing the F-Stop (reducing the aperture) lengthens the depth of field.
Perfect, you would think, but no.
Though this did do as promised, it also meant that the image was far too dark. There are two ways to deal with this:
1. To dramatically increase the lighting.
2. Increase the ISO number.
Now as we were in a studio we were able to increase the lighting to an extent, however, it was also necessary to increase the ISO. This brought its own problems. Grain.
Grain is a nightmare, it makes keying difficult and the footage looks awful. Noise reduction plugins are available, but often make the image look out of focus.
The answer?
There isn't one, you have to compromise.
Lower the F-stop, so the green screen is less in focus, but using bright orange track markers makes tracking easier.
Reduce the ISO reduces grain, with the lower F-stop the image isn't as dark.
Increase the lighting to allow for the highest F-stop and lowest ISO possible.
In the end the footage looked ok. I used a neutral flat setting so the footage on it's own looks rubbish, but once taken into post the keying is easier and the noise easily removed. In hindsight it would probably have been much easier to use the Z7 for studio work, as it has a much higher depth field so these issues are irrelevant.
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