Lens for Green Screen Key

[Dinh Hung]

Hi guy, Iam using Canon 60D for Shooting Green Screen, but i look my video not sharp, please tell me, what lens is best for Green screen key.
Thanks.

Test key MC - final - YouTube

[Dave Partington]

I don't think there is any one lens that I would recommend over any other.

I've shot green screen with 50 f1.4, 24L f1.4, 35 f1.4L, 24-70L, 24-105L, 70-200 f2.8L, Samyang manual lenses and more. I don't see much in the way of difference from one lens to another.

If you're struggling for pixel definition and you don't need super wide subjects then turn your camera sideways (to portrait mode) and then rotate it back in post. You'll get more pixels to play with (because your 1080p will now be on the vertical) and you can fill more of the sensor. The subject in your example is perfect for this technique.

Shallow DOF can help blur the background, but you don't really want to blur the edges of the subject too much because it will be harder to key.

Adding a back/hair/rim light will help separate your subject from the background more easily too.

The next thing is to carefully expose your subject and adjust colour (and sharpening) in post so it doesn't stand out as being shot separately. Sometimes de-noising the shots can help too.

[Dinh Hung]

Thanks Dave Partington.

[Chris Harding]

Hi Dinh

If your screen is big enough then also get the talent to step forward a bit towards the camera ... with the talent right up against the screen you can easily focus on the screen rather than the talent so she would look a bit soft in post .. you can always zap a mask over the outside edges of the screen if the shot is too wide too so the green screen doesn't have to completely fill the frame either. I have keyed with 3 chip cameras which have a huge DOF so that usually isn't an issue but with a tiny DOF your position needs to be more precise so the talent is always sharp as a tack

Chris

[Adrian Tan]

I think Dave's reply is excellent.

Re lens, I once watched a DP shoot green screen where he went into the camera settings and reduced detail. I assume this was because it would make the green more even. But, assuming you've lit it evenly to begin with, and there's no spill on the subject, maybe, all things being equal, sharper is better where lenses are concerned, to be able to get detail on hair etc.

Random thought: I remember a lot of talk about chroma key when the original Superman movie came out. Never thought that, 35 years later, I'd be able to shoot green screen in my bedroom and apply the effect with the click of a button.

[Richard Gooderick]

If you have something like an ipad there is a very good app called Greenscreener that will help you get an even exposure across the green screen.

If you have an even exposure it should be easy to get a good key.

Assuming that you have at least a metre of distance between the subject and the screen and no light spill or reflection from the screen eg on spectacles.