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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

100fps - lowlight and grain

J

jahno

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hey there,
i was wondering about the varispeed and the loss of light/aperture.
i hope i did not lose sight of any threads about that topic.

we were shooting about 10 firefighters in front of a burning door at night.
only light was a 400w HMI toplight. and later the fire behind the door.

but it looks like we haven't even lost any light due changing from 25fps (1/50) to 100ps (1/200). how is that possible?

after watching the footage in redcine i noticed very grainy dark parts.
may it be that there's a grain boost bla thing that boosts the light?

the operator also recognizes that he was able to shoot up to 15mins without changing the 8gb CFs.

any comments, experiences or stuff about that?

best regards
jahno
 
I don't understand why you didn't loose light, it should have been two stops. Did you compensate with the ISO setting? That would explain the grain. Red One is a great camera, but not extremely low-light.

15 mins is normal: If you shoot 100fps, you are shooting 2K.

Greetings from next door ;-)
 
thanks nomad and tim,
i'll try to change the shutter option.
what does "relative" do? is it something like grain boost bla?

@ nomad: no iso changes. always 320 @ 5000K
 
The answer: It's not possible, our universe doesn't work that way. Something else is going on.

If you had shutter at 1/200th on both, then I could see this happening.

Are the RedCine settings absolutely identical for the regular and varispeed shots? Brightness or exposure would compensate, much like ISO. Curves as well could be compensating the brightness.
 
Hey Jahno

Couple things could cause the grains, your metadata might be at different ISO setting.

"Relative" Shutter mode means: (Shutter is locked in the camera, and you are in charge of shutter angle) This means that if you are ramping shutter will stay at the locked angle. Example: 180deg (1/48) @ 23.98 and 180deg @ 120fps.

"Normal" Shutter mode means: Camera controls the shutter, so if you ramp
from 23.98fps to 48fps the shutter will compensate the stop.

Extra space on your CF Card could be shooting @ 2K as Nomad said or could have RedCode28 setup. That will give little extra space, depending on the color details.

(Did You use Build 16 or 17?)
 
I think I can help on this as well-

You absolutely need to go into relative shutter mode. Look under shutter settings. Switch to relative. When you begin to set your overcrank FPS you will see it get darker for sure.

We have been doing a bunch of over-cranking stuff here, and the grain issue is caused by a few factors.

Because you are now in a 2K mode, you are basically zoomed in on the chip. So whatever noise that was there in the 4K mode, is basically magnified. That is the only bummer with 2k overcranking. You will see more grain, and the image looses some sharpness.

If your lens is wide open- IE: 2.0, 2.8 - then the softness will be even more visible. If you can, close down that lens a bit. 5.6, 8.... anything but totally open.

I noticed you had one HMI light. I am very curious as to what lighting temperature you had set on the camera. Was the camera at 5000K or 5600K? Or did you have it at 3200? I am guessing you had it set at 5600K for the HMI light.

If not- anything that is lower then 4500K begins to induce more and more noise. 3200K will have a fair amount of noise in the blacks and grays. If you go under 3200K for any reason, you are seriously starving your blue channel of light. Avoid it at all costs if you want to avoid noise.

You guys may laugh, but we don't even white balance the camera hardly anymore- unless outside during the day. Once I see the white balance starting to go under 4500, I don't white balance anymore. I just adjust our lighting to it. In some rare cases I will go to 3200 and accept the noise that is in the blacks. In 4K it is small for the most part. If I am overcranking, I will avoid 3200 at all costs.

So - try to keep that white balance 4500 or higher to help avoid noise.
Try to not use a totally wide open lens during overcranking
And go into relative shutter mode! That is very important!

Hope this helps a bit.
 
thanks for your answers,
as i said before... we always shoot on this settings:

asa320
wb 5000K (why? because of some tests, that told us to stay on the chip's native color temp)

shutter mode: wasn't able to look it up yet. i will do that tomorrow
and there absolutly no changes made in redcine...
I will have a look at quicktime renders tomorrow. maybe it's just a r3d thing

the 4k-2k thing seems to be the most logical way to explain the grain if there's no hidden grain boost inside our lady.

we had to shoot @ f1.3/1.2 (different lenses from the old arri-zeiss hs series)
 
We have been doing a bunch of green screen work.

I discovered the whole 5000K thing by doing some research and by chatting with some fantastic people on this board.

It is not that they are telling us to leave it on 5000K because that is the native setting for the chip- You can wander around, but be prepared to see the grain at lower settings.

Since we moved over to 5000K in the green screen studio, we have been nailing these keys.

I feel that your issue is that you were in the 2K overcrank mode. It is a wonderful thing to be able to overcrank, but you do pay the price a tad.

I am interested in what the new chip will do for overcranking.

This is why I am seriously interested in the epic now. A 5K overcrank at 100fps would freaking rock.
 
thank you a lot guys! love you! :clown2:

we already decided to buy this epic X pack :)

best regards
jahno, berlin
 
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