BMPC 4K or GH4 for green screen: what would you do?

[TheRenaissanceMan]

You guys saying the GH4 can't stand up to a 10-bit 4:2:2 camera realize the GH4 outputs 10-bit 4:2:2, right?

[hmcindie]

Have you guys never done any greenscreen work in your lives? j.f.r obviously hasn't.

The lighting, how you shoot it and your software skills play a way more important role than the camera you use. As long as you don't shoot with a potato.

[jax_rox]

22 minutes ago, hmcindie said:

The lighting, how you shoot it and your software skills play a way more important role than the camera you use. As long as you don't shoot with a potato.

Yeah, but better bit depth and colour info is always going to better/give you a key easier. Doesn't mean it can't be done.

3 hours ago, TheRenaissanceMan said:

You guys saying the GH4 can't stand up to a 10-bit 4:2:2 camera realize the GH4 outputs 10-bit 4:2:2, right?

If that's being used, sure. That wasn't specified though.

[TheRenaissanceMan]

8 hours ago, jax_rox said:

If that's being used, sure. That wasn't specified though.

Fair enough. Just thought I'd float that out there for anyone who forgot/didn't know.

[jax_rox]

3 hours ago, TheRenaissanceMan said:

Fair enough. Just thought I'd float that out there for anyone who forgot/didn't know.

Wouldn't the cost of a GH4 + external recorder push it up to the same as a BMPC anyway..?

[Jonesy Jones]

Just now, jax_rox said:

Wouldn't the cost of a GH4 + external recorder push it up to the same as a BMPC anyway..?

Yes, higher even. And data storage costs would be at least equal. So no point in that. But thanks for the input R man.

[TheRenaissanceMan]

Eh...BMVAs are cheap. And the GH4 offers very different strengths and a lot more versatility. I'd take a BMPC personally, but both are great options.

[hmcindie]

20 hours ago, jax_rox said:

Yeah, but better bit depth and colour info is always going to better/give you a key easier.

But if that's the only thing you are focusing on, then you might screw it up even if you shoot with an Alexa and RAW. Because there's no way the camera will fix A) poor lighting (and that will destroy the key, no matter what you use), B) poor software skills (not doing a proper key but just pressing one button on the Premiere Ultrakeyer and hoping for the best). Even Hollywood films with huge budgets send some of those greenscreen shots to India to be rotoscoped because they can't fix their own greenscreens. And they don't shoot with either a GH4 or BMPC (which are both good enough for greenscreen work, BMPC maybe slightly better because you can enhance the greens a bit more before the key but it can make aliasing on the edges of sharp lines - and that's a bad thing when keying - so then you have to fix those manually...)

So attack the lighting first. Make sure you can separate the actors and the BG so that there are no shadows on the greenscreen and as little spill as possible. Make sure that you have tracking marks if you are moving the camera around. Make sure that you don't have to manually mask anything out. Shoot it properly (don't shoot wide and then except to crop in because "it's 4k!". Plan those shots! Then attack the software side. Learn what ever system it is you use (I use Keylight in AE but I do a semicustom pass with and I don't just drop it in and wait for it to work immediately). Go through possible tutorials. Try your own methods. You might have to key separately different parts of the screen (hair vs hard lines). You will have to add motion blur to the key too afterwards so movement doesn't look too unnatural. Etc etc.

If those things are working for you, then you are 99% there and the pick between the BMPC and the GH4 is trivial.

[jax_rox]

11 minutes ago, hmcindie said:

But if that's the only thing you are focusing on, then you might screw it up even if you shoot with an Alexa and RAW.

Of course, but the assumption was that everything else is equal, in which base higher bit depth and more colour information is going to work in your favour every time. Getting everything else right is very important, but all else being equal the BMPC will still key easier. And as I said above, allows a lot more room for error.

If everything else is 100% perfect, the GH4 will be easy to key as well. But how often is everything else 100% perfect? Realistically, even if the GH4 takes only 5 extra minutes to get the key right because of its bit-depth and lack of colour, multiply that over the amount of videos you're doing and you can end up with hours of unnecessarily wasted time.

I do agree with you that the actual setup is more important than the camera, however. But I don't think the choice is between a BMPC and no lights in a small room versus a GH4 in a large room and a full lighting setup. Though, I could be wrong.

[M Carter]

On June 15, 2016 at 11:38 AM, Jonesy Jones said:

Have you seen this video? (Yes I know that this is the BMCC not BMPC. The point is that the GH4 keys nicely.)

Ummm... the GH4 keyed nicely in comparison to the BMC because it has almost twice the pixels and can hold more detail.

The BMC4K gives you the extra pixels and much more color data.

If you're really set on the GH4, add an NX1 to your tests. Don't know how it keys, but (my opinion) it smokes the Panasonic for IQ. Really remarkable little camera and you also get APS-C vs. the little GH sensor. 

On June 17, 2016 at 2:20 AM, jax_rox said:

Of course, but the assumption was that everything else is equal, in which base higher bit depth and more colour information is going to work in your favour every time. Getting everything else right is very important, but all else being equal the BMPC will still key easier. And as I said above, allows a lot more room for error.

If everything else is 100% perfect, the GH4 will be easy to key as well. But how often is everything else 100% perfect? Realistically, even if the GH4 takes only 5 extra minutes to get the key right because of its bit-depth and lack of colour, multiply that over the amount of videos you're doing and you can end up with hours of unnecessarily wasted time.

I do agree with you that the actual setup is more important than the camera, however. But I don't think the choice is between a BMPC and no lights in a small room versus a GH4 in a large room and a full lighting setup. Though, I could be wrong.

I've pulled hundreds of keys as far back as the Panasonic HMC 150, not even a full-raster chip. But we spent 2 hours just prepping and stretching lighting a very big screen, and lit our subjects properly. (and delivered 720 as i recall). It can be done, but I'd prefer as many pixels and all the bit depth I could get.