Dragon cold operation and noise.

[Ian Planchon]

I just got back from a 2 week shoot following the iditarod with my Dragon. I kept my camera on all day, and at operating temp. green across the board, but I was still getting a lot of red pixels/noise in the blacks even after a black shade. The ambient temps were hovering around -20 to -50 degrees the bulk of the time.

How do I post an R3D in this thread so I can show you what I was seeing?

 

[Christopher-lee dos Santo]

From my understanding, One needs to keep the dragon sensor warm to get rid of excess noise. Do you recall what the core/sensor temperatures that you were shooting under where?

I stand to be corrected, but from what I have heard/read, anything under 35 degrees is not considered warm enough. Even though your T/E are green. I have seen cleaner images with a 45/55 temperature blackshade than a 35/45 temperature blackshade, even though both had green T and E symbols. If that makes sense.

Good practice is to let the camera warm up for 30 minutes, then blackshade and keep the camera at that running temp. -20 to -50 ambient temperatures must be pretty hard to keep the camera warm, I imagine.

 

[Ian Planchon]

I was in the 40/60's most of the time. There were some times that it dipped below that, but for the most part it seemed like the core temp was good enough. is there a way to see that info in RCX?

 

[Jeffrey Loewe]

I shoot in cold temps frequently and experience the same issues. I usually turn my camera on in my bag when on the mountain to let it warm up. Just make sure to keep moisture out of your bag/case as it will cause the lenses to potentially fog.

I have experienced this as well. It's usually at night though or in storm weather.

 

[Ian Planchon]

Yeah, I would start it up in my portabrace backpack and leave it in there for an hour. then pull it out and let it settle to ambient temp, then blackshade. still pretty noisy. I will say that the black shade is the most annoying part of dragon.

 

[Matt Ryan]

If you are using the Skintone/Highlight OLPF you will see red noise in the blacks. With your R3D's, select the DEB checkbox in RedcineX and see if that removes it. That is what DEB was created for was to remove the red noise. Try it and if it works, there's your solution.

 

[Ian Planchon]

I did check DEB, but it didn't get rid of everything. definitely made it way more useable though.

good to know that its a Skintone OLPF issue adding to it though.

 

[luigivaltulini]

I did check DEB, but it didn't get rid of everything. definitely made it way more useable though.

good to know that its a Skintone OLPF issue adding to it though.

Post r3d still.

 

[Ian Planchon]

would love to, just not sure how. I asked about that in my first post.

 

[Matt Ryan]

would love to, just not sure how. I asked about that in my first post.

In redcine X, load the clip in the viewer and click the R3D snapshot button below the viewer next to the snapshot button... Snapshot button looks like a little dslr. Then take that R3D snapshot and upload it to dropbox or some other hosting site. Post the link here and we can download it and take a look..

 

[Ian Planchon]

I knew the R3D part, just not how to post it here. was trying google drive to no evail. I will try drop box!

 

[Ian Planchon]

here is a link to the R3D

https://www.dropbox.com/s/w5lf8jxspp1tows/I009_C020_0316ZL.0005717F.R3D?dl=0

 

[Hal Long]

DEB seemed to tackle much of the red noise in your still. The noise looks pretty evenly distributed with DEB on. There's still quite a bit of lens chromatic aberration where she or her equipment are framed by the snow. Your tint was at -11 and was highlighting the magenta of the CA. With that zeroed out it looks much better.

 

[Matt Ryan]

After looking at the R3D I'd conclude it's a combination of underexposure, skintone/highlight olpf red noise, high compression ratio, and tons of chromatic aberration from your lens. Shooting at 800ISO and still underexposed, plus a compression ratio of 15:1 will not get you very clean results. I'd check out the low light olpf at 800ISO and try at least 8:1 compression. Like Hal mentioned, your tint was off a bit which added to the red noise.

 

[Ian Planchon]

I'm not sure about the under exposure. in the high key situation it seemed like a good balance. as for compression, I was shooting 96fps, so 8:1 wasn't really an option.

chromatic aberration is a surprise to me, I haven't really had an issue with that on the RED 300mm prime, I didn't notice it at first till I zoomed in on it after it was mentioned. Luckily after grading in resolve it was pretty decent. but I was surprised at how much noise there was.

You think its better to run an low light OLPF in high key scenes like this?

 

[Matt Ryan]

I'm not sure about the under exposure. in the high key situation it seemed like a good balance. as for compression, I was shooting 96fps, so 8:1 wasn't really an option.

chromatic aberration is a surprise to me, I haven't really had an issue with that on the RED 300mm prime, I didn't notice it at first till I zoomed in on it after it was mentioned. Luckily after grading in resolve it was pretty decent. but I was surprised at how much noise there was.

You think its better to run an low light OLPF in high key scenes like this?

Your shot was a bit underexposed. I bumped it to 2000ISO in redlogfilm to get a good looking image. Personal taste but even at 2000ISO your highlights are far from clipping. So you could have opened up more.

I'd recommend either the low light olpf if you need to shoot at 800ISO or shoot at 250 ISO with skintone/Highlight OLPF. When I shoot skintone/highlight olpf, I expose the camera for 250ISO to avoid any noise.

This was shot at 250ISO on skintone/highlight and has no noise whatsoever and entirely used every stop of dynamic range without clipping or crushing (no light augmentation, all natural):

 

[Ian Planchon]

damn. thats exactly what I should have done.

alright, next time will be better.

thanks for all the help everyone!

 

[Matt Ryan]

damn. thats exactly what I should have done.

alright, next time will be better.

thanks for all the help everyone!

I posted your image above after you replied, but thought you might wanna take a look. I bumped the ISO to 2000 and still the snow did not clip so you had more room to open up. Of course it's personal preference but thought it might be beneficial.

 

[Ian Planchon]

thats pretty much spot on the image I ended up with in resolve. I have been so used to shooting at 800 iso as my baseline, I keep forgetting that this camera has so much more to play with now.

thanks again!

 

[PatrickFaith]

That footage is totally usable for 1080p. Main issue is 15:1 compression. I can email the jpeg of it, for some reason gets munched a bit when i upload it to reduser.

Here are the nuke nodes (i had to save the file to openexr then imported to nuke):


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