RED Scarlet-X - intense noise in blue channel

[David Strüning]

Hello guys,

I know that there are some threads about visible noise in the blue channel. However, I need a specific opinion on this one. Therefore, it would be great if you are able to help me out.

I recently shot a short film with the RED Scarlet-X of my university. Due to internal communication problems of the staff, we were not able to do a previous camera check. On set we then recognized an intense noise in the blue channel which is according to my DP and 1st AC not normal. We talked to the RED support who (after he checked the .tiff files and log file we sent him) also confirmed that this is not normal. So far so good, there are a lot of people who say that this is not normal. However, the staff of my university is not willing to believe that there is something wrong with the camera. Below you can download an image which shows the effect. If you load this into REDCINE-X Pro, watch the scopes in RGB mode and mouseover nearby pixels, you can easily see the untypical strong difference in the blue channel. What do you think?

Download test file
ASA: 800
Gamma: REDgamma3
Color Space: REDcolor3

Best regards
David

 

[Peter Majtan]

The camera needs to be properly black-shaded for intended exposure/temperature combo - have you done that?

 

[David Strüning]

The camera needs to be properly black-shaded for intended exposure/temperature combo - have you done that?

Thanks for your time Peter. For sure, after the camera warmed up we did the black-shading.

 

[David Strüning]

This is a screenshot of the fullscreen video (full quality) in 100% mode, blue pixels all around the image are visible (not only in the dark areas).

 

[Patrick Grossien]

If your staff doesn't believe RED support I don't think they will believe us any more than them?!

 

[Patrick Grossien]

David where are you located? Maybe it's possible to arrange a meeting to make a comparable shot with a second Scarlet (which I guess you have no access to) for you to show the staff.

 

[David Strüning]

If your staff doesn't believe RED support I don't think they will believe us any more than them?!

Thanks for your time Patrick. I know, it sounds weird that the staff does not believe the RED support. However, it would be great to have more objective opinions about this situation.

 

[David Strüning]

David where are you located? Maybe it's possible to arrange a meeting to make a comparable shot with a second Scarlet (which I guess you have no access to) for you to show the staff.

Thanks for your support, I am located in Hamburg. I know that it is not that perfect circumstance to deliver a judgement, but what do you think about this image quality?

 

[Patrick Grossien]

David, I'm not seeing that kind of blue noise with my material. The noise doesn't look that patchy. Even when I try to underexpose as much as you did, it looks different.

Did you use any kind of filters on the lens, on the light? What light source did you use?

1 - update firmware. You're still running on 4.0.18 - not that this should be a deal breaker, but still just to eliminate every possibility you can. have them install the 5.1.38 release firmware. it's a world of difference!
2 - black shade again and check if the temperature and exposure indicators are both green when filming
3 - use more light - check your goal posts
4 - try to film @ 5600k and white balance in post to see if you that makes a difference

that said I tried to break the image just now, and couldn't get it to what you're experiencing. Try my tips anyway to see if it makes a difference.

 

[Gunleik Groven]

Downloading, but from the screenshot it looks a bit underexposed...

 

[paul schefz]

looks underexposed and unfortunately normal to me....i would set iso to 500 or 640 and stay away from the goal posts....

 

[David Strüning]

David, I'm not seeing that kind of blue noise with my material. The noise doesn't look that patchy. Even when I try to underexpose as much as you did, it looks different. ...

That is exactly what the DP and 1st AC said. Once you underexpose the image there is noise but this does not look that patchy.

... Did you use any kind of filters on the lens, on the light? What light source did you use? ...

The test file I posted earlier was shot without any filter on the lens/light. We did not use any special light source, just a standard tungsten bulb.

...
1 - update firmware. You're still running on 4.0.18 - not that this should be a deal breaker, but still just to eliminate every possibility you can. have them install the 5.1.38 release firmware. it's a world of difference!
2 - black shade again and check if the temperature and exposure indicators are both green when filming
3 - use more light - check your goal posts
4 - try to film @ 5600k and white balance in post to see if you that makes a difference

that said I tried to break the image just now, and couldn't get it to what you're experiencing. Try my tips anyway to see if it makes a difference.

I know that the firmware is not the newest one, but without the permission of the university I am not aloud to make any software change. Thanks for your tips, I will consider them.

 

[David Strüning]

Downloading, but from the screenshot it looks a bit underexposed...

looks underexposed and unfortunately normal to me....

This patchy noise appears also in images which are not underexposed. So I would not really believe in this as the reason for the patchy noise.

....i would set iso to 500 or 640 and stay away from the goal posts....

I think the sensor's native ISO is 800, right? Therefore, using this value should result in the highest possible dynamic range. Or is there any error in reasoning?

 

[Hans von Sonntag]

David,

from experience I'm pretty positive that the camera needs a stop at the repair shop.

If I were you (every here an then I teach at university and know the topology) I would give the person an official report and claim the camera as defective and the footage hardly usable. Then he's is forced to take action. This may lead to an other shelf-sitter but chance are not low that the camera will be sent back via Berlin home to Red.

Hans

 

[Patrick Grossien]

I know that the firmware is not the newest one, but without the permission of the university I am not aloud to make any software change. Thanks for your tips, I will consider them.

Hehehe that's why I wrote "have them install it" force them
I have been teaching at a university for the past couple of years and I know that it's tough to get staff to do stuff you want them to. One thing that could work is if it's still under warranty than they have to act quick. If not then you would have to convince them that a high quality camera which is not giving out the high quality images it is supposed to, needs a visit at the repair shop because it's otherwise senseless to have it in the first place.
The university is required to have funds for the maintenance of the equipment, so this should be a no-brainer anyway!

 

[Patrick Grossien]

This patchy noise appears also in images which are not underexposed. So I would not really believe in this as the reason for the patchy noise.


I think the sensor's native ISO is 800, right? Therefore, using this value should result in the highest possible dynamic range. Or is there any error in reasoning?

Your mileage may vary. a lot of people state that you should stick to 800 a lot of others say different, and in the end: ISO is just metadata and shouldn't actually affect the image. Just like color temperature. But it also makes you react to the image you see and the choices you make can definitely impact your image.
The rest is purely a trial and error thing and getting to know the camera. Then you can decide for yourself how much the setting of white balance and ISO affects your image quality.

 

[Patrick Grossien]

Gunleik, aren't you also a promoter of staying at ISO800 and 5600K during shooting?

 

[David Strüning]

David,

from experience I'm pretty positive that the camera needs a stop at the repair shop.

If I were you (every here an then I teach at university and know the topology) I would give the person an official report and claim the camera as defective and the footage hardly usable. Then he's is forced to take action. This may lead to an other shelf-sitter but chance are not low that the camera will be sent back via Berlin home to Red.

Hans

Hehehe that's why I wrote "have them install it" force them
I have been teaching at a university for the past couple of years and I know that it's tough to get staff to do stuff you want them to. One thing that could work is if it's still under warranty than they have to act quick. If not then you would have to convince them that a high quality camera which is not giving out the high quality images it is supposed to, needs a visit at the repair shop because it's otherwise senseless to have it in the first place.
The university is required to have funds for the maintenance of the equipment, so this should be a no-brainer anyway!

Thank you both for your statements, they confirm what we already thought. Now there are statements of the DP and 1st AC (experienced in shooting RED cameras), the RED support, several german high-end rental houses and the community here. In my opinion the staff now really need to react!

 

[David Strüning]

Your mileage may vary. a lot of people state that you should stick to 800 a lot of others say different, and in the end: ISO is just metadata and shouldn't actually affect the image. Just like color temperature. But it also makes you react to the image you see and the choices you make can definitely impact your image.
The rest is purely a trial and error thing and getting to know the camera. Then you can decide for yourself how much the setting of white balance and ISO affects your image quality.

Thanks for your advises. I will definitely get more hands on RED cameras in order to get familiar with their science of digital imaging processing and the consequences on image quality.

 

[Patrick Grossien]

David, you can always call RED Germany and plan a little trip to Berlin if you want to try out the cameras and maybe get some help there. Truly nice guys and girls there!