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Slowmo footage very noisy all of a sudden :/

Dominik Muench

Dominik Muench

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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:

sarah.jpg


what can I do to improve this ?

The Epic firmware is on the latest beta version.
 

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Good question. I had similar happen last spring. Went out shooting in the rain, black shade for default 24fps. Everything looked great. Switched to some 300 fps and the darks danced with flies. Only thing I can think of is that I didn't re-black shade for 300fps. Maybe you needed to do this too? But you said you've done this previously with satisfactory results. The blacks in the image don't look too extreme. Not like the solid dark rock faces on my shots in spring.

Hopefully your questions has a solution. Leaving it up to chance is pretty dumb.
 
I will try and find a screenshot from material I shot a couple of weeks ago in the same location with similar conditions and settings and its waaaay cleaner than what I managed to get yesterday. The black shading wasn't really an issue in the past for me.
 
yeah that's a bummer, wish someone else would help us out trouble shooting.
 
Always try and black-shade with the AC plugged in. I had this issue before where I did a BS on battery, got noisy blacks at high speeds. Re-black shaded and haven't had the issue since.

Couple things to always keep in mind which you prob already know:

always black-shade with the RED cap on. may want to throw something over front of cam too to keep it as dark as possible (when shooting outside)

let sensor come up to normal operating temp before blackshading

good idea to perform the factory preset black shade, not user HS. also BS at current FPS.
 
The only thing I didn't know was the AC cord being plug in makes a difference. I'm doing everything else. It's bullshit we have to BS this camera all the time or some ghost in the machine switch electronics on us. Sounds more like superstition to me. In the field, to switch black shades between FPS speed is a real pain. Especially if I have to haul a genny to power up the AC plug.

So I either BS for 300fps or 24fps. Two days for shooting to get what I want. What if the rain stops? Maybe I can figure out a solution to use a car bat and the lighter plug for 30 min. Then I gotta hope my BS worked, the first time. If it failed....

So there should be a BS saving option for this reason. I can set "preset" BS for FPS and temp and have at it in the field. Freedom.
 
Chris McKechnie said:
Always try and black-shade with the AC plugged in. I had this issue before where I did a BS on battery, got noisy blacks at high speeds. Re-black shaded and haven't had the issue since.
Click to expand...

Did you BS for high FPS or default when you get the noisy blacks? The re-shade was at the same settings?
 
thanks chris maybe I shall give that another try tonight. maybe I need to let the camera heat up properly beforehand.

will there be noticeable changes if I calibrate for lets say 300fps and then shoot some more on 25fps ?
 
i think i even had similar things two years ago with RED MX - blacks lifted noisy and bluish while high speed.

corrct me if im wring but i think for BS it doesnt matter if you choose user or factory before the shade. i think it is after the shade that with these two options you can choose between the factory made one at red when the camera was born and the laste Shading you just did yourself

Why we cannot save multiple BS Presets yet ( or i just dont know how?) is a mystery to me, especially since BS takes a looong time.

--> RED Techs, this would definitley be a firmware feature for the future
 
Did you make sure the camera was well into its operating temp range? I always run it even hotter and it makes a difference. RED are always very quiet on this issue, why don't you send in a report and try get an answer from support?
 
Dominik,

I didn't realize you didn't let the camera heat up beforehand. Definitely gotta do that. If that fixes your problem, let us know.

Dominik Muench said:
thanks chris maybe I shall give that another try tonight. maybe I need to let the camera heat up properly beforehand.

will there be noticeable changes if I calibrate for lets say 300fps and then shoot some more on 25fps ?
Click to expand...
 
Dominik, you gotta give it like half an hour, let the temp max and even out. 55% fan speed is too much. Go down to 35% to get it nice and hot. This has been said to make a big difference.

Try and gauge the temp of the location you'll be shooting, use the fan controls to stabilize the temp at the desired location temp. Lower fan speed = hotter, higher fan speed = cooler.

I think you are well on the way to making this issue.... as Jim would say... OBSOLETE.

Dominik Muench said:
how long do you usually let the camera idle before you black shade brigham ? I waited around 10 minutes and reduced the fan speed to 55%.
Click to expand...
 
The camera shot off is above 80. So at 75, you'll get an orange light.

I'm usually in the 37-42 range. Your good. I wouldn't worry about heat, it will top off and stay level at some point.

Again, try to match you BS temp with the ambient temp of the spot you'll be shooting. If you need the fan quiet, try BSing at a higher temp. Use the fan speed to get your temp to your desired level. Will take some testing but better than picking up noise on a beautiful girls butt. :)

Dominik Muench said:
thanks Will, I just wasnt too sure about the temperature in the past....whats the hottest max I should be aware off ? 35% fan speed seems very low. when I had the cam at 55% it got hot quite fast.
Click to expand...
 
At 72c the temperature display will turn yellow
At 74c it turns orange
At 75c the user speed is overridden and fan goes to max speed. Even if recording.
At 76c the temp display will turn red. Although max fan speed usually prevents getting there.
At 77c if you are recording, the record will be stopped
At 83c the camera will shutdown
 
doing BS for each frame rate is just plain....pain in the ass. I have not done that yet, never needed to. But I will try and see the results.

Also BS it hotter.

Anyways, just my opinion on both the issues, isn't this a bad thing, if we have to do this to get great results?
 
Ok I did a short test today and the footage is still very noisy....I let the camera warm up for a good 40 minutes, then did a custom blackshade for my shooting settings, 240fps, 2K, 8:1:

here is a very short sample, this was taken in the middle of the day in bright sunlight with a shutter of 1/1000 of a second at F5.6 with my 17-50mm RED Zoom, ISO 800.

as you can see there is considerable noise and grain in the dark hair area, the black ink on her tummy and her whole left side of the body as well as the yellowish looking rocks in the background...these are NOT compression artefacts of the video file, this noise is in the RAW file as well when viewed in RedCine-X at full resolution:

[video]http://blacksun-productions.com/leah.mov[/video]

as comparison, this video was shot a couple of months ago with 300fps in 2K-WS during sundown so there was much less light and the footage is much cleaner:
 
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