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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 :)

Noise

D

Damian Grady

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We shot some slo-mo footage a couple of days ago at a local college at 100fps on our Epic-X and if I'm honest I'm a little dissappointed by the image quality. To me is seems pretty noisy coniserding the sports hall was pretty well lit and the aperture was wide open. The shutter was at 200/sec and iso was at 1600.

Here's an R3D and RMD snapshot: https://www.dropbox.com/sh/xcube0oedfb7gth/0c51zuLb6h

Am I doing something wrong here?

Any help and/or advice would be very much appreciated.
 
Was it correctly exposed for 1600 ISO or was it underexposed despite shooting wide-open? It is noisier than other shots you've done at 1600 ISO?

Saying "it seemed pretty well lit in there and I shot wide-open" doesn't sound like you took an exposure reading of any sort? Keep in mind that you lost 2-stops of light by shooting at 100 fps, so it would have been the same as shooting at 24 fps with a 400 ISO camera in terms of the light levels needed.
 
What David said. Also did you black shade at this frame rate and shutter speed. That makes a pretty big difference.
 
Hey guys, thanks for the replies. I didn't black shade no Phil as I didn't have time. It was an unscheduled part of the shoot and the game only had 5 minutes to go so black shading would have taken too long. Good point though.

That's also a very good point David however I have achieved better results than this in similar lighting conditions without taking an exposure reading. It was all a bit ad-hoc this bit but it was either shoot something or have nothing to shoot.
 
Ah. Then I'd say this noise was introduced via the lack of black shading. It's an important step if you want out of camera clean high speed material. Takes 10 minutes to do on set. Or you can spend more time in post fixing it :)

Interestingly, Dragon performs better on this front as the noise floor and temperature regulator on the sensor seems to keep the sensor within calibration temp with a 180 degree shutter from 24-72 fps and at 96fps I think it was safe at 1/144th. I'll certainly be testing that more.
 
he could have black shaded earlier in the day, or a week prior, and saved the black shade settings in the camera, correct? and simply switched back and forth?

if one were to do this, is the proper method to blackshade on 'adaptive' so that you know the temp will always be the same temp you black shaded at, regardless of the location temperature?
 
I dont think it is that important to do new blackshade when using a little faster shutterspeed. Its more important with slow.
 
Black shading is not supposed to effect 'random' or 'grain like' noise.
It only effects the so called 'fixed pattern noise' which is a static held grain type of thing.
I verified this technical detail with Graeme N.
 
I'd be curious as to what the histogram, goal posts and stop lights looked like when this was shot. ISO is somewhat irrelevant unless you are exposing with the eye and being a little careless with these other tools.

Some times I think people don't understand that no gain is ever introduced into the recorded signal on a RED. So noise is not introduced ion this manner. It's all about making sure that anything you don't want to be black is NOT in the showing up in the left goal post. Ideally, whatever shows up in the left goal post you would crush to black in the final image.

At least that's my take. :smiley:
 
Edit: Just checked out the R3D and it is just classic underexposure. No way to get this shot noise free without reduction at that exposure level.
 
I have opened the frame in RCX and it is very underexposed even at 1600 ISO (the histogram is way to the left), so I think your eyes may have fooled you when you say the court seemed pretty well lit. Besides, you were shooting at 100 fps (with an aperture of F4), and , as Mr. Mullen points out, you were sacrificing 2 stops there. My guess is that you may have relied too much on what you saw on the EPIC LCD (images tend to look brighter)
 
Also - I am not an expert in high frame rates but woukld it not have made more sense to shoot at 1/100th of a second rather than 1/200th?
 
Blackshading wouldn't have mattered much; you shot at 1/200 (2+ stops darker than 1/48th) at F4, indoors without any additional lighting... Your midtone/18% grey is pretty darn low, very much underexposed. Even at 1/48 it probably would have be better at f2-2.8. Factor in gaudy fluorescents (presuming that's what the gym is using) and you're in for a world of hurt when you balance those out and try to make up the ~4 stops (of the higher shutter speed and slower lens)... I mean look at how much magenta needs to be added to get rid of the green cast... That's basically boosting the blue-channel - the weakest one - by quite a damned bit to compensate for those lights.

Fortunately it seems pretty uniform noise, so noise reduction should take a lot of it away. More so when you downscale to HD.

@Terry: 1/200th (180deg) makes sense for 100fps... but when it's this under lit, I would have sacrificed "proper" motion blur for the extra stop...
 
Have people suggesting blackshading actually looked at the shot? This is underexposed, flatly lit footage. Saying it's black shading does a disservice to the original poster as it leads him to believe that it was the fault of the camera rather than his production budget. It was not shot properly for the clean images you'd expect from a production that has tons of money to light an entire basketball court.
 
Jake Bastian said:
Have people suggesting blackshading actually looked at the shot? This is underexposed, flatly lit footage. Saying it's black shading does a disservice to the original poster as it leads him to believe that it was the fault of the camera rather than his production budget. It was not shot properly for the clean images you'd expect from a production that has tons of money to light an entire basketball court.
Click to expand...

+1 it's only basic exposure skills not being applied..
 
Damian Grady said:
Someone advised me on here that I should set this at twice the number of the frame rate.
Click to expand...

That is the usual approach; particularly when shooting "normal" footage. But you have a tradeoff here. At 100 fps there is tremendous potential for underexposure -as you found out - and getting an extra stop of light by shooting at 100th would have, IMO, been an improvement.
 
Terry VerHaar said:
That is the usual approach; particularly when shooting "normal" footage. But you have a tradeoff here. At 100 fps there is tremendous potential for underexposure -as you found out - and getting an extra stop of light by shooting at 100th would have, IMO, been an improvement.
Click to expand...

Thanks for the top Terry. Much appreciated.
 
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