Blackmagic Forum

Hello,

My camera is experiencing very noticeable horizontal noise and harsh lines in lower light footage (shadows). Noise is acceptable of course but the lines with different brightness values is a problem.
The strange thing is, the upper ISO range 1200 and above does not have this issue whatsoever. Just very even noise throughout. Which is very easy to remove. I tried PIXEL Remapping but of course that would not solve the issue but I was desperate to try something.

I've attached 3 stills. Two at ISO 1000 to pronounce the issue (all issues are present throughout the entire lower ISO bank) And one at 3200 showing very even acceptable noise. The affects are more visible in the video.

You can also see the issue when viewing false color when monitoring. (The lines are present)

I know the sensor needs light but the horizontal lines seem like something is wrong.
Thoughts?

Thank you!

There are two native ISO's on the Pocket camera.

One is at 400 and the second one is at 3200.

at 1000 you're amping up the 400 quite a bit and you might find that you have a cleaner result at ISO 3200. It's counter intuitive, but you can get cleaner blacks at 1250 than 1000 because it's not he threshold of when the next gain channel switches in. But the choice is...

Add some gain to the lowest native ISO...
Use the higher native ISO instead and shoot it pulled down....

I don't have the camera in front of me, but from memory the next ISO kicks in just above 1000 at 1250. You'll notice as you go up will suddenly clean up in the noise in the blacks.

So you're at the very highest gain of the 400 ISO at 1000 OR you can go to the lowest gain of the next highest dual ISO native bracket at 1250.

JB

John Brawley wrote:There are two native ISO's on the Pocket camera.

One is at 400 and the second one is at 3200.

at 1000 you're amping up the 400 quite a bit and you might find that you have a cleaner result at ISO 3200. It's counter intuitive, but you can get cleaner blacks at 1250 than 1000 because it's not he threshold of when the next gain channel switches in. But the choice is...

Add some gain to the lowest native ISO...
Use the higher native ISO instead and shoot it pulled down....

I don't have the camera in front of me, but from memory the next ISO kicks in just above 1000 at 1250. You'll notice as you go up will suddenly clean up in the noise in the blacks.

So you're at the very highest gain of the 400 ISO at 1000 OR you can go to the lowest gain of the next highest dual ISO native bracket at 1250.

JB

Thanks for jumping in John! Much appreciated.

While I surprisingly do understand the way the Dual Native ISO works, I normally don't shoot 1000. I was just using that to show the issue more clearly, which also like you described is also affected at 400, the native ISO since 100 - 1000 is the same with a different curve.
I normally like shooting at 640 or 800 to get more stops in the highlights but since the curve is the only difference, the harsh horizontal lines in the shadows exhibits on all ISO's under 1250 including the native of 400.

My plan is, if I have to, shoot low light at 1250 and above to clean the shadows. Unfortunately I lose stops in the highlights.
Your first choice of "Add some gain to the lowest native ISO" unfortunately just brings the horizontal noise issue right back in because it was there to start with. And loss of stops in the highlights.

Are you saying that this issue is present in all 6K pocket cameras?

Well, they seem to have about one stop less DR than the UMPs and every camera is showing some issues if starved of light and then pulled up. The second ISO range of the Pocket cameras is impressive, even a Sony A7S (aka the night owl) isn't really seeing that much more, it's actually just smoothing noise and detail out.

I wouldn't lift a black sky, but rather pull it down to black. No electronic camera is recording true black, but video noise instead.

If the fence or those trees are of importance, give them some light.

Uli Plank wrote:Well, they seem to have about one stop less DR than the UMPs and every camera is showing some issues if starved of light and then pulled up. The second ISO range of the Pocket cameras is impressive, even a Sony A7S (aka the night owl) isn't really seeing that much more, it's actually just smoothing noise and detail out.

I wouldn't lift a black sky, but rather pull it down to black. No electronic camera is recording true black, but video noise instead.

If the fence or those trees are of importance, give them some light.

Thanks Uli! I appreciate the thoughts. I've researched some online videos with BMPCC6k shooting night scenes utilizing ISO400 and I did not notice any horizontal line noise issues.

I guess the bigger question I would like an answer to is if this is an issue with my sensor or do all 6k's have this inherent problem?

Maybe someone from BM can lend their opinion.

Thank you!

Well, I still have a 6K Pro around for a few days.

You can shoot a test or two with the lens cap on and pull it up until you see the lines.
Tell me the values and I'll try to reproduce it.

Uli Plank wrote:Well, I still have a 6K Pro around for a few days.

You can shoot a test or two with the lens cap on and pull it up until you see the lines.
Tell me the values and I'll try to reproduce it.

Hi Uli,

Thanks for offering to test.

I just recorded different flavors of Braw (8-1 & 12-1) 5.7k & 6k with the lens cap on and had the same issues.

ISO 400 - raise and lower the gain in resolve to show different variances of dancing horizontal noise (lines).
ISO 3200 - very even noise. Nothing that would show horizontal or vertical.

I also tested a dark room with a lamp in the corner. The issue shows wider "horizontal lines".
The lens cap test shows more narrow "horizontal lines".
Again, 3200 very even noise.

I'm curious to see what you come up with.
If anybody else would like to try, that would be great!

Thank you!

I sometimes get horizontal lines in very dark areas of the frame when shooting in the lower ISO ranges on the Pocket 6k Pro. However, the shot has to be pretty under exposed and I find that it's not very noticeable unless I'm really pixel peeping. I also think applying some noise reduction and maybe a de-flicker filter in Resolve makes it even less noticeable.

Matthew_Lawrence wrote:I sometimes get horizontal lines in very dark areas of the frame when shooting in the lower ISO ranges on the Pocket 6k Pro. However, the shot has to be pretty under exposed and I find that it's not very noticeable unless I'm really pixel peeping. I also think applying some noise reduction and maybe a de-flicker filter in Resolve makes it even less noticeable.

Thanks for your input! Appreciate it.
I have tried noise reduction but it doesn't help the dancing horizontal lines.
Unfortunately they are noticeable without pixel peeping.
I have not tried the de-flicker filter. I will give that a shot!

I tested it with the cap on at 400 and 3200 ISO.
If I pull the gain up to insane values, I can see very faint horizontal waves at both ISO settings, but they are pretty much covered by the noise at 3200. To see them I need to increase gain and/or contrast in the shadows to levels well beyond practical use.

So, to tell you if your camera is behaving normally, you'll need to post short samples from yours to a transfer service, so I can compare. For me, it's a non-issue.

BTW, these might be high frequencies wandering around in the camera. After all, the input stages are analog.

Uli Plank wrote:I tested it with the cap on at 400 and 3200 ISO.
If I pull the gain up to insane values, I can see very faint horizontal waves at both ISO settings, but they are pretty much covered by the noise at 3200. To see them I need to increase gain and/or contrast in the shadows to levels well beyond practical use.

So, to tell you if your camera is behaving normally, you'll need to post short samples from yours to a transfer service, so I can compare. For me, it's a non-issue.

BTW, these might be high frequencies wandering around in the camera. After all, the input stages are analog.

Thanks for testing!
I guess it sounds like my camera does have some problems. I don't need to push the levels that hard to have unacceptable results.
It looks like I will have to contact support to see what options I have to fix the issue.