Wed Apr 19, 2017 5:33 pm
I would stay away from small stil, zooms like his, the IQ is not very good, and they are not very sharp.
To,pull,a good Chroma Key (green screen) you need a nice sharp fast lens, not a small, slow still zoom like this. Your results will be disappointing.
Again the focal length needed to cover 8-feet is going to depend on the camera to subject distance.
A 12mm lens will cover 8-feet width at at a 8-foot subject to camera distance, 9-feet will give a 9-foot width image, this is one of the nice things with the 12mm. But using it close in will cause some distortion, so I would go with a Oly 14mm prime lens, or the Panny/Leica 15mm. All can be had used on eBay for $200-400.
A 15mm, for example will give 8-fret of coverage at 10-feet, a 16mm Veydra Mini Prime (a very excellent lens, similar IQ to the Zeiss Super Speeds) will cover 8-feet at 10.5 feet, a 17mm Oly Prime at 11-12 feet will also cover your 8-foot area. The longer the focal length, the better the perspective if shooting a person in your setup.
Of all the lenses listed so far, the Oly 17mm would be the best choice, (or the Veydra 16mm which is more expensive) and will give a "Normal" looking perspective for shooting a person. But, if you have the room, a longer focal length would be better yet. ( I have a Veydra 16mm for sale if you are interested, PM me)
When I was doing TV promotion Chroma Key shots on a AF100/MFT sensor, we used a 35mm for most the of the shots, covering a 8 foot background area at about 15-feet from the green screen, subject was 6-8 feet from the screen, which is about as close as you want to get to the green screen to the subject.
A Panasonic 20mm f/1.7 II or a Sigma 19mm f/2.8 would give you about the same coverage at this distance, which is about as close as I would go to the screen, to keep the screen at least one-stop underexposed against the subject. Both are fairly compact lenses, the Panny is the one I would choose over the two, as some Sigma lenses have issues with BM cameras.
A monitor with a Wave Form monitor is a real asset getting the lighting even on the screen. Also an IOS application called Green Screen will help.
Cheers
Denny Smith
SHA Productions