Slowmo footage very noisy all of a sudden :/

[Björn Benckert]

Ok So found your problem

You shot in 2K 2to1
You will have much cleaner, less noisy results by shooting 4K with the Scarlet and 5K with the EPIC
Unless you are forcd to go to 2K by shooting high speed in this case you did shoot high speed 240fps
I understand this forced you into 2K
Give 5K 120fps a try and then process your footage threw twixter if you want to slow it down more.
That is a very helpful solution.
Or if you can get away with 4K or even 3K highest resolutions staying out of 2K you might like the results better
Whatever you do give them all a try and see what works best for you.


PS i understand youve seen good images shooting 2k 300fps under your same conditions
try shooting at iso 640 opening up your lens a touch more without over clipping those highlights



Best of luck

Luis, It's worth mentioning that Twixor does not always solve without artifacts. It's more like one of these things that work for some shots but a lot of shots... does not work well at all.
So a little warning, do not go out and shoot something at one frame rate and promise your client that the rest of the slow down will be done with twixor or any other motion interpolated slowdown, as non of them work for any kind of shot. It's all depending on how your foreground move over your background, if your background is out in blur, etc. So a test shot might work superbly then when shooting with a higher Fstop twixor might just not do the trick at all, with the exact same scene...

 

[Adrian Jebef]

Hi Karl

I looked at some footage that I shot last week....just catching up with the transcoding now...and this footage I shot at 320 ISO instead of 800....you're right. its definitely cleaner at that ISO range.

this is what came back from the RED Support after I sent them an R3d and camera log file, seems to be a number of factors coming together:

The camera appears to be fine. There are no indications of anything going on sensor or hardware related.
I believe the problem just has to do with the high shutter settings you are using, mixed with the high compression and lowered resolution. This is why the problems you are seeing is showing up primarily in the blacks. I would recommend using your exposure check, as you have a very bright sun, mixed with very dark elements in the shade, especially the black hair.

Your Blackshading methodology sounds accurate- it's exactly what we would recommend using those settings, so you are good on that.

The only other suggestion would be the lens itself- There appears to be some chromatic aberration using that lens- it is possible the focus is slightly off, and I would suggest testing your back focus adjustment. It is possible the back focus settings are slightly off.

Honestly, increased noise and lack of resolution will always be a problem when you go any lower than full-frame 5K with the EPIC. When you go high-speed you are physically blowing up your image. Anything shot at 2K is technically inferior. Your best bet to get less noise is to expose at native sensor sensitivity (320-400 ISO). Noise reduction and sharpening software (like DaVinci Resolve) can help considerably on the back end.

 

[Paul J Steinberg]

I agree, the 2K 300fps quality is really poor. The Red One's 2K 120fps was usable (found the grain/noise similar to 16mm film) but the Epic's 2K isn't something I'd be comfortable recommending.

Just currious, has anyone tested the new 512GB highspeed cards? At $4000 they're too expensive to buy and try. I'd like to see the results of the lower compression ratios on highspeed material before I invest that amount into new media.

 

[Bryan Moore]

We shot some 2k 240fps stuff on epic inside of a cnc machine and I was suprised on how well it came out. I figured it was gonna look like death. But came out totaly usable.

 

[Will Keir]

I think Bjoern is going in the right direction, the noise looks the same when my shots are underexposed. How to fix this? Can you put ND filters to take the highlights down and expose the blacks?

thanks for that Lu, I will give it a try, shot everything in 96fps 5K yesterday, a lot of it in very low light situations and the footage is really nice and clean. I will definitely give twixtor a go.

hey bjoern i ll try and get one done tomorrow. might give HdrX a try on my next shoot. you have a droidworx rig ?? were flying one here in Australia with my Epic on it....great fun those

 

[Will Keir]

Your best bet to get less noise is to expose at native sensor sensitivity (320-400 ISO).

Native ISO on the Epic is 800. Shooting 320 ISO is a technique some people use to not under expose their shots in dark environments.

 

[Will Keir]

You should be able to rent these cards.

Just currious, has anyone tested the new 512GB highspeed cards? At $4000 they're too expensive to buy and try. I'd like to see the results of the lower compression ratios on highspeed material before I invest that amount into new media.

 

[James T Mather]

Native ISO on the Epic is 800. Shooting 320 ISO is a technique some people use to not under expose their shots in dark environments.

The sensor is 320 Asa. The opposite is true. Shooting 800 is recommended by Red as a means of highlight protection (the way kodak used to slightly overclock their stocks) but if you are using this ASA as a baseline for exposure you will have (very) slightly noisier footage - personally I prefer this. You can test this by switching between RAW and other colour spaces.

 

[Will Keir]

Dom,

If you could use a faster lens to do these tests, open up full and stop down with NDs, I am thinking you wouldn't see this issue. When I get my set of super speeds I'll give this test a go and let you know what I found. Won't be for a little while yet.

In a high contrast area, you might consider applying HDRx too.

 

[Robert Berger]

Hi Guys


I had a shoot yesterday where I shot everything at 240fps - 8:1 compression and when I got home I found the footage to be much noisier than usual.

The shooting conditions were quite good, it was all in bright daylight, so the sensor had plenty of light. I shot with a Zeiss 21mm F2.8 Distagon lens and I black shaded the camera body before the shoot. Not to this exact frame rate and exposure because it keept varying for different scenes but I did the factory default black shade.

I've shot under these conditions and with these settings many times before and in the past the footage always looked great and very clean, even in low light and when shooting 300fps at 12:1 compression, which is why I'm so surprised about these results.

Here is as still frame out of redcine X, straight from the unaltered raw image and as you can see there is considerable grain and noise in the darker areas of the image:

what can I do to improve this ?

The Epic firmware is on the latest beta version.

when you shoot highspeed in 2K in 240 or 300 fps, take the lowest iso you can, at this moment it is 250 iso and in the lowest compression codec. Don't under expose and over expose. T0 much over exposed will the highlights be crushed. You will get clean beautiful slomo's. I do it everytime.

 

[James T Mather]

Yeah, I've had no problem with 300fps on a commercial intercut with Epic but you've got to watch exposure and give it plenty of light. It sounds like underexposure is your problem. It is softer, true. But for HD tv it's perfectly workable - provided you have a thick neg and make sure you're shooting around 5000-5600 kelvin so your colour channels are clean.

 

[Adrian Jebef]

Dom,

If you could use a faster lens to do these tests, open up full and stop down with NDs, I am thinking you wouldn't see this issue. When I get my set of super speeds I'll give this test a go and let you know what I found. Won't be for a little while yet.

In a high contrast area, you might consider applying HDRx too.

Opening up the lens and adding ND's just cancels each other out. Are you thinking of ND Grads?

And as James notes, the EPIC's base sensor sensitivity is ISO 320-400. The camera clips highlights in a very unflattering way so the manufacturer has "recommended" we underexpose by a full stop to compensate.

 

[James T Mather]

That is assuming your shot content has overexposed areas. I would have thought it is part of a DoP's job to deal with that.

 

[Dominik Muench]

when you shoot highspeed in 2K in 240 or 300 fps, take the lowest iso you can, at this moment it is 250 iso and in the lowest compression codec. Don't under expose and over expose. T0 much over exposed will the highlights be crushed. You will get clean beautiful slomo's. I do it everytime.

thanks for the advice, I will give that a try on the weekend.

 

[Karl H]

Hi Dominik

The sum of it really is that yes you're going to get more noise zooming in but you can still get great results depending on what you're shooting. Twixtor equally has it's limitations and may not work at all depending on your subject.

The sensor is 320 native, not 800. At 800 you're underexposing the sensor - fine in most cases but not in slo-mo or if you need to dig into shadows. My opinion is that Redcode Raw is a bad choice for anything high ISO and an RGB codec would eliminate this problem... But once you know it's limits you can work around it. As most people have said, shooting low ISO and lighting for that is key - as is choosing the lowest compression the fps will allow. I know it sounds ridiculous but anything in the blacks/lower part of the histogram is prone to dancing shadows so it's best if you can overlight/overexpose (without clipping highlights) and crush the shadows later. This will help with compression and also visible sensor noise. Follow this mantra and you can get some really nice looking stuff even at 2K. The only way is to test. You can always try shooting 3K too and see which gives you the best compromise you're willing to live with.

Shooting 5K is not a foolpoof solution either. You can get terrible compression artifacts in slo-mo at 5K (check my old thread where I had bad results ... http://www.reduser.net/forum/showthread.php?78098-Epic-compression-artifacts-in-slo-mo&highlight= ) After this, I tested and tested until I understood exactly how the system records/performs. Since this test I had better results shooting lower ISO and opening the iris more. Avoid high dynamic range scenes if possible, keep that histogram as far to the right as you can at 320.

 

[Dominik Muench]

Hey Karl

thanks for that, I will do some testing on the weekend with different formats and ISO settings....my understanding is that twixtor gives better results when the footage is shot with a faster shutter ??

 

[Karl H]

it does yes. As it's essentially tracking pixels it helps if they are clearly defined with no motion blur. You can always shoot something like 3K and then try to twixtor it further. The slower footage you put into it, the better results you'll get out.

also depends on what you're shooting. something against a blue sky will work out better than something on a really busy background where you might get uncontrollable warping.

 

[Will Keir]

So you drop the ISO, that does nothing in camera. Meta data. Your results are from exposing your shot with more light coming in.

when you shoot highspeed in 2K in 240 or 300 fps, take the lowest iso you can, at this moment it is 250 iso and in the lowest compression codec. Don't under expose and over expose. T0 much over exposed will the highlights be crushed. You will get clean beautiful slomo's. I do it everytime.

 

[Will Keir]

Opening up the lens and adding ND's just cancels each other out.

I was thinking that perhaps if the blacks and already deep black, using ND's will take the highlights down, leave blacks, still black but allowing you to open the lens up for a bit more exposure.

Doesn't work?

And as James notes, the EPIC's base sensor sensitivity is ISO 320-400.

Why do you guys keep misinforming each other. I got it straight from him, the native sensor ISO is 800. Fincher has a few custom made Epic's just for him that our rated 320 ISO.

 

[Will Keir]

Karl,

You seem to have a bit of wisdom but this get's frustrating. If the native sensor is 320 ISO, why do the people at RED, top down, including the engineers continually state it's a 800 ISO native camera? Why does Jim tell us Epic is a 800 ISO camera?

I've underexposed the camera at 800 ISO, maybe in practice you are right, you get great results at 320, but this is because your over lighting your shots and Epic's can handle more light better than less. I have shots that look totally bleach white yet didn't clip.

If you are getting no noise in dark situations at 2k, 300 FPS you are certainly doing something right. I have had similar problems to Dominik at 800 ISO. 2k 300 FPS in daylight, and the dark part of the rocks danced with flies.

Perhaps the 800 ISO rated native sensor is 5k 24fps and with slow motion work closer to 320 ISO at 2k 300 fps?

The sensor is 320 native, not 800. At 800 you're underexposing the sensor - fine in most cases but not in slo-mo