View Full Version : D90 & Keying

Michael Carter
11-20-2008, 12:21 PM
Hi all - anyone done any keying tests with the Dmovie at full res?

I'm not too happy with keys from my DVX - how does that JPEG compression hold up?

Thanks - MC

11-20-2008, 02:49 PM
Here is a still split before/after from a short piece I did. Used colorkey and keylight in AE.

11-20-2008, 04:44 PM
that looks pretty good, can u give us like a few more frames! lol

11-21-2008, 12:36 AM
You can't judge the capability of the footage for keying by just one picture. Neither by a fast action scene with just 1 second of keying. If you want to see if it's actually good, you'd have to record some boring testfootage, just an actor posing, moving a little here and there.

My verdict after working with uncompressed footage from a pro blue screen studio is:

Compression sucks for keying period.

Newb that I was, i thought: man these files are huge! Lets try a good codec...oh here this looks good, MJPEG! Oh wow this is great, fast AND small! But wait...why can't I get rid of the jittery alpha...oh no, it's the codec...
Looking at the footage blown up to 200%, you can clearly see the JPEG artefacts, which make it nigh impossible to get clean and sharp edges without the noise. A friend of mine had the same problem with his HDV cam.

So no the D90 sucks just as well...but hey, that won't keep me from doing short and fast clips outside, where I don't have the good studio equipment. I'm thinking of shooting portrait format if it's just one person. Then I'll have the whole 1280p in height.

11-21-2008, 03:13 AM
Keying is mostly about how you set the light. I think you get good results with the D90 in most cases with proper light. Big fuzzy hair is always a problem but there are many useful effects to use in AE.

Atleast the chroma bandwidth isn't limited as it's with HDV.

11-21-2008, 08:11 AM
Ok, the light is important. At least to minimize noise, which is a problem to. But if the MJPEG compression is to high, you get artefacts along the edges. Considering the variable compression quality, I'd say: try to key just one person at a time and keep the clothes simple, to many details and the compression kicks in. The next important thing ist the green or bluescreen. It better be as smooth as possible. Ok that's always important, but i think the compression makes everything more difficult. Everything has to be perfect for it to work.

11-21-2008, 10:09 AM
A couple of weeks ago we did a green screen job for a graphic package were making for a new show (broadcast) here in sweden. We used the hvx200 (without adapter) as our main camera but I brought my d90 for Short DOF close-ups (50 1.2). The keys look good. HVX200 is better but its much better than i.e HDV. This week we did another green screen shot for a promo (music video) were maiking and we used the EX3 for the first time - and its a lot better then the HVX.

11-21-2008, 02:27 PM
The keys look good. HVX200 is better but its much better than i.e HDV.

You lost me here Karsvall... were you saying that the D90 is better for keying than HDV. Or was I reading your statement wrong. I have both the nikon D90 and Canon A1 and was very curious which one is better for keying.

11-21-2008, 03:41 PM
I read it as the HVX200 is the best, then D90 and last HDV because of the low bandwidth mostly in the blue channel.

11-21-2008, 06:20 PM
I did a short chromakey test with the D90, from my experience I can tell you that it was easier than the same scene done with my Sony FX7... a lot easier. ok its only like 2 seconds (car hit) but it was really easy to achieve.

11-21-2008, 06:51 PM
You got i right.

1. HVX
2. D90
3. HDV

But, there is, of course, cameras better then the HVX out there.