Chroma key

[Brigante]

Hi everyone!

This is my first post and I'm an absolutely newbie. I hope I'm not asking a silly question...

I'd like to know if it's possible to make chroma keys with super 8 film. I don't know if film grain is an insurmountable obstacle to get a good result, or if you can do it just being carefully and following some tricks.

Any advice will be very very welcome, because I'm planning a shortmovie where chroma is an important thing.

[johnnhud]

Being a new user of super8 myself. I have also wondered about this. The answer is probably yes, but only if you go with a negitive stock like V200T or 500T and get a really clean transfer done.

I doubt that 64T will work very well because it has a higher grain than the negative stocks.

The most important thing will be to make sure that your green or blue screen is really well lit.

If you do this and have lot's of patience and some good photoshop skills, you should be fine.

[audadvnc]

Welcome to Filmshooting, Brigante!

I cannot speak from direct experience, however the general opinion among filmmaking enthusiasts is that matte techniques such as luminance keying or Chromakey work best with high resolution images; Super 8 is, due to its tiny frame size, inherently lower resolution. If you try a chromakey of a Super 8 image you will likely see quite a bit of edge keying artifacts that may or may not detract from the final result. But the best way to find out if it will work for you is to make a test; shoot your subject in front of a blue or green screen, transfer to video and run the chromakey effect to see if it's what you have in mind.

Also note that the background image can be Super 8 without a problem, IMO it's merely the foreground matte image that may have artifact issues.

[tlatosmd]

There's a thread on this topic here that's a few months old...

[Brigante]

Thank you very much for your advice.
I'll try what you said. Anyway, if there is someone there who could tell us his/her experience shooting chroma keys on super 8 I'll be very glad.

Johnnhud suggested a negative stock. I think my budget doesn't allow me to shoot the enterely movie in negative film, and I guess to shoot a part on 64T and the chromas (I mean the whole scenes where chromas will be use) on V200T will be very noticeable. Or could it be fixed in post?

Thank you very much and sorry for my bad English.

[Brigante]

I looked for a post on this topic before I wrote, but I didn't find anything

[johnnhud]

I guess to shoot a part on 64T and the chromas (I mean the whole scenes where chromas will be use) on V200T will be very noticeable. Or could it be fixed in post?

I probably won't be extreamly noticeable. Since you can't shoot croma with a high grain stock, maybe consider shooting all your background imagery (plates) on 64T and then your greenscreen objects on MiniDV. This will give you a higher quality image that is already digitized. You can then use the higher rez advantages to apply your croma effects correctly, then use a filter in post to desaturate and add grain to the DV image. Playing with these settings will probably get you something pretty close to the 64T image. Plus if you use DV for the green screen, you won't have to use as much $$$ film trying to get the two images to sync with each other.

[Arislan]

and then your greenscreen objects on MiniDV. This will give you a higher quality image that is already digitized.

You're joking, right?

[audadvnc]

There is something to be said in shooting blue/green screen in DV and your background in S8, but the problem is that the combined image will have both film and video originated elements. It may look weird or unnatural, like a horse with a sheep's head...

[johnnhud]

You're joking, right?

um, no I'm not. I would much rather waste 60 minutes of DV tape trying to get the sync correct than bruning through reels and reels of film. Also, if your trying to tell me that 64T would be easier to lift an image out of a croma background than DV, I think your wrong. I have done this several times in Final Cut Pro with DV footage.

I just think that the DV shot of an actor against a greenscreen would be easier to lift than a grainy 64T shot. He said he didn't have the $$$ for negative stocks, so I was giving him an alternitive.

[BigBeaner]

Color Negative 16mm is the best bet. Search this site we've talked about some guys in Ireland shot a movie that looks better than Matrix and Sin City with just a few props, actors and green screen using this process.

Also use the compositing of After Effects.

[tlatosmd]

I looked for a post on this topic before I wrote, but I didn't find anything

Here it is: viewtopic.php?t=10858&highlight=blue+screen

[christoph]

This is my first post and I'm an absolutely newbie. I hope I'm not asking a silly question...

I'd like to know if it's possible to make chroma keys with super 8 film. I don't know if film grain is an insurmountable obstacle to get a good result, or if you can do it just being carefully and following some tricks.

Any advice will be very very welcome, because I'm planning a shortmovie where chroma is an important thing.

hiya and welcome,

first of all may i ask how much experience you have with chroma keying and with compositing in general? which programs (and plug ins) will you be using? and what's the subject matter of your short and what will be the final destination? how are your backgrounds generated/shot? how important is that it looks completely convincing?

those are all important factors to decide on the best format...
generally pulling a good chroma key of super8 is pretty hard and needs a lot off extra work and money. you'd have to shoot on vision2 200T stock (or lower), you'd have to pay for an expensive transfer, preferably on a spirit and to uncompressed 10bit 4:2:2 video, and you'd have to put a lot of work into stabilizing and degraining the footage (which lowers the quality).
16mm will make this easier (and more expensive), but you still need top end transfer and a some post processing.

if you do this for the look of it, go ahead, but if you're short of money and want clean results you would have it much easier to either shoot with a rented high end SD video camera (the panasonic DVCPRO50 ones are great value for the money - digibeta is really much better but way more expensive in the end) or one of the prosumer HDV (or DVCPRO HD) cams and get excellent result, specially if you downconvert to SD in the end.

personally i'd borrow the canon HDV, transfer over firewire, convert to uncompressed HD, do some chroma smoothing, key and composit it, keep an HD original and downconvert to uncompresed SD for digibeta/DVD. total cost maybe 100 EUR for the camera for two days (the rest can be done on any home computer).

hope that helps a bit and feel free to mail me if you have any specific problems
++ christoph ++

ps: make sure your greensceen lighting situation matches with the background
pps: DV is actually not that hard to key if you know some tricks.. but it will always look a bit soft

[Brigante]

Thanks to find the topic, tlatosmd.

Christoph, thank you very much for your advice. It has been very helpful.
I haven't got any experience shooting chroma keys, but I hope to work with a good DP. I’m finishing the script and I just wanted to know if it would be possible to do what I’m writing.

The scene that I’m worried about is located on a train, where the landscape that you can see through the windows will be make by blue screen. The landscape won’t be shot, but made on a computer, and the point is that it must look as a computer-generated landscape. At the same time, I want for the whole scene a film look (to be a bit more precise, a super 8 look), that’s because I’m wondering if I could shoot it in that way. The main part of the short will be shot on DV, with the Sony DSR 390 DVCAM, and edited with FCP.

I really appreciate your offer to help. If you don’t mind I’ll mail you when the shooting dates will be closer asking for advice.

Thanks.

[christoph]

mixing a CGI background with a super8 foreground seems like a weird thing to me, gonna be a nightmare to match. it's much easier to have two clean sources and "degrade" the image in the end.. unless you want an arteficial seperation of the two layers of course.

here's a few things to look out for while shooting:

- use a greenscreen, not a bluescreen (for both film and video)
- if shooting film, overexpose the stock a stop
- if shooting video, turn down the incamera sharpening (often labeled detail) to the minimum
- try to match the lighting situation in the foreground to the background.

++ christoph ++

ps: for some greenscreen tests of various cameras, check dvxuser.com and dvinfo.net..
i just did a quick composite with DV and DVCPRO footage from a HVX:
http://voon.dyndns.org/hvx/DV25vsDV50.jpeg
and one in the DVCPRO HD space:
http://voon.dyndns.org/hvx/final-key-grad.jpeg

(if you want to mess around yourself, the originals were)
http://voon.dyndns.org/hvx/DV25-Green.png
http://voon.dyndns.org/hvx/DV50-Green.png
http://voon.dyndns.org/hvx/HVX200_Key2_01-orig.png

pps: you are NOT gonna get this kind of result if you just try to composite in your editing suite... you'd need at least after effects or something better.
so if you really want to go the super8 route, shoot a test chart, have it transfered to uncompressed video, and i'll see what i can do ;)