Af100 for green screen shooting???????

GRENCH

GRENCH

Well-known member
I'm aware that shooting greenscreen should be pretty sweet with the AF100 when recording to an 8 bit recorder in 4:2:2 via the sdi out put, but I'm wondering how well it holds up using the internal recording function. We won't be purchasing an external recording unit for several months. Does the image hold up when keying images recorded on the sd cards?

I'm extremely curious. If anyone has done test I would love to see it. I have searched and haven't seen a good test as of yet. We have been using the HVX200 for our green screen shoots and are currently awaiting the delivery of our AF100.

Thanks!!!!
 
Here's a test I did on a green screen (2nd half of this test) against the RED. You be the judge (internal codec only).


I'm sure Shooter will be along shortly to show you his kick-ass green screen grab from the Wendy's spot he did.
 
I've done a few green screen shoots in native codec without any troubles at all. The fellow doing the compositing gave very positive feedback about the image and ease of compositing.

Light your green screen well --- so its flat on the waveform with minimum thickness of the wave form line . Light your subject as needed and you should be good to go.
 
Mark Smith said:
I've done a few green screen shoots in native codec without any troubles at all. The fellow doing the compositing gave very positive feedback about the image and ease of compositing.

Light your green screen well --- so its flat on the waveform with minimum thickness of the wave form line . Light your subject as needed and you should be good to go.
Click to expand...

What IRE do you typically bring your screen to?
 
monkeyking said:
Mark, what determines thickness of wave form line?
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the WFM representation of the green screen has 2 dimensions. The dimension most people look at is the horizontal one left to right. Is the line flat, bowed , tilted, all of which are effects of uneven lighting. The other dimension which is less examined is the thickness of the line of the WFM line. Assume that you've got your screen lit to 50 units perfectly so you have a trace across the WFM at 50 units without any slopes or bows in it. Set a frame which is your widest shot and look at the thickness of the WFM trace. Now either zoom in or move the camera in to a tighter frame and compare the thickness of the WFM trace to the one you saw in the wide shot. The trace in the tighter shot will no doubt be much thinner than the wide shot. The trace thickness represents un even illumination from top to bottom of the frame. As you even out lighting from top to bottom , the WFM trace will get thinner, and pulling your key will get easier.
 
Thanks Mark!
I never realilzed the line thickness was a function of the y-axis lighting.
You can teach an old dog new tricks afterall.

chris
 
I'll add that the vertical lighting differences tend to manifest themselves to a greater degree as the size of the green screen goes up. So you'll likely see more vertical illumination problems on 10x20 than on a 8x8, but if you are sloppy you can see vertical illumination probs on almost any size screen
 
Benjamin Eckstein said:
What IRE do you typically bring your screen to?
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With me it is about 50 IRE.

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I light my key bgs approx 2 stops under my subject.

Subject read incidental and bg read from spot meter ( reflected)
 
Matt and Shooter, both of your keys look really, really good. I am curious what kind of a light kit (kit or your own collection) you all use for a basic key, both to light the screen and the subject.

Edit: I think I remember seeing a really good green screen still that you did Shooter?
 
blackcat said:
Matt and Shooter, both of your keys look really, really good. I am curious what kind of a light kit (kit or your own collection) you all use for a basic key, both to light the screen and the subject.

Edit: I think I remember seeing a really good green screen still that you did Shooter?
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I pull lights out of the truck to light key shots ( and everything else). Over the years of pulling keys ( and I have shot lots of them)...its no real mystery to me. I have used many and various light units / sources to illuminate key BGs.

I will add... I have used many lights of many styles to illuminate key bg s... but today ... I used green kino tubes on my chroma green screen for the 1st time. Results were amazing.

Key lighting : Its basic, documented and fundamental.

Evenly lit color screen. Left to right , top to bottom ( Green / Blue)
(Ability to read waveform info , incidental and reflected light meters .....helps a lot)

1. Separation of subject to BG ( Distance )

2. Back light and rim light to eliminate key BG spill and influence..

3. Exposure and levels - Key BG 1 - 2 stops below subject. ( Incident on subject..reflected on BG)

4. Lens choice and DOF to suit BG ( insert / composite)

Good post skills ( or access to them) to pull Keys.

It kind of simple.


BTW: I am no fan of digital key bgs for interior situations. Chroma BG colors are easier to manage exposure wise.
 
I have green kino tubes for my Divas and its kind of freaky how big of a background you can light with a couple of divas with green tubes and the right physical space. One has to be very careful with managing green spill when using green Kino bulbs.
That said I'm finding the physical space where you situate your greens screen, especially on location to be the one thing that nobody ever talks about but can have a very large effect on the outcome. freedom to place-position lights where needed in relation to the screen position will have a great deal to with how successful you will be in lighting your screen, and therefore the final result.

I'm generally placing subject a stop above background but I feel less like there is a hard and fast rule . I've had situations where the background was hotter than the subject work just fine and of course the reverse as well.
 
Matt and Scooter.

Thanks for the wonderful footage, still and info guys.
One Question????
Have any of you guys tried keying using the Reflex Media light ring and bead cloth with the AF100 or other camera? Curious to head some experiences. We are looking at using it on some of our mobile shoots.
 
Thanks for all the great info! I have a large portable green screen that I am using for my own projects, but I haven't used it for any paid gigs yet. I have had some fairly decent results with my screen, including my lighting setup. I do watch the separation of the subject to the background. That seems so crucial. Most of what I am doing up to this point is more abstract, so matching DOF and lighting--on the subject--to create a convincing illusion for the background has not been a huge issue. However, I do plan to experiment soon with that.

The samples that you all sent look really great.
 
Separation from the subject to the background is probably the #1 thing that newbie keyers get wrong. You need as much separation as you can possibly get. Minimum of 10 feet, and preferably a lot more.

Even lighting is the other issue. 4' flous do a good job, but it's best if you can have them above and below, rather than from the sides.

The reflecmedia brings its own set of issues. With that, you want the absolute minimum distance from subject to background that you can get, to keep the awful shadow from appearing, and you want as much camera-to-subject distance as you can manage, to keep from spraying green light on your subject and ending up with green eyes and green teeth... my experience with the reflecmedia is that it's six of one, half dozen of the other. If you're in the field and you don't have a proper lighting kit, it shines. If you're in close quarters and can't get separation between the background and the subject, it's better for that. But for anything else, I prefer conventional greenscreening.
 
I'm generally placing subject a stop above background but I feel less like there is a hard and fast rule . I've had situations where the background was hotter than the subject work just fine and of course the reverse as well.
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True ...but the less reflectance coming off the BG onto the subject the better and it's easier to work the key.

Another tip....flag / mask / matte as much of the BG off the front lens element. A blue or green reflection on the lens is not helpful and generally there is a lot of it because the key BG is usually at 90 degrees to the lens.

Green tubes in Diva Units. I was amazed how much coverage and output 2 x Divas on floor stands had on my 20 x20 green screen ( Chroma Green). We flatlined the waveform with the thinnest of lines I think I have ever seen. I think we had 5.6-8 ( 400 iso !!!) Glad we didnt have a digi green.
 
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