Low shutter blackshades super sensitive

[Robino_J]

I have blackshaded 1/2th shutter @46c and when the temp is off by 1 degree, the image starts shifting with a green cast.

Is this normal? I don't notice this as much at higher shutter calibrations.

 

[ericyoung]

I imagine first that 1/2 sec exposure is a pretty long exposure time, so will tend to exaggerate any shifts.

Secondly 46 deg C is a low temperature to calibrate at. MX typical operating temp was around 65 deg C if I recall, and Dragon certainly prefers at least 65 deg C. Running the camera for any length of time, 65 deg C is a much more realistic temperature to maintain, whereas 46 deg C will be a struggle to maintain at an even temperature across the sensor.

At least that's my theory, until you get an official Red answer! :smile:

Try calibrating at 65 deg C.

 

[Anton Shavlik]

I also noticed the red channel getting crushed quickly when doing a time lapse. I now use frame integration to better manage it which seems to work.

 

[Michael Lindsay]

Irrespective of temp the dragon is not in our experience as capable a camera as Epic MX for 1fps work... I think Red should consider removing the problematic frame rates from the options till they solve it...

As Anton suggests frame summing or averaging is a potential way around this.. But we have also had some crazy results with this approach.

M

 

[David Battistella]

Hi all,

i have to to say I am having the opposite experience. I find that if I black shade the camera with the exact settings I capture at the results on dragon are stunning. No color issues at all.

Is there anything in the image path? Nd?

what is the lens and aperture?

 

[Robino_J]

Here's a 1fps time lapse shot at 1/2th Shutter going from 46c to 48c. The issue doesn't have anything to do with lenses or aperture - this test was shot on a Canon 50mm 1.2 @ F4

Password: bs

Link for tablets: https://vimeo.com/130215986

 

[ericyoung]

Are your T/E indicators on the display staying green?

 

[Robino_J]

Are your T/E indicators on the display staying green?

It's green @46c then yellow at it's going up to 48c (i think it might be red at this point I don't remember...)

But as you can see in the video, even at 47c there's a huge shift and it's in the yellow. The video shows from 46c to 48c start to end.

 

[ericyoung]

It's green @46c then yellow at it's going up to 48c (i think it might be red at this point I don't remember...)

But as you can see in the video, even at 47c there's a huge shift and it's in the yellow. The video shows from 46c to 48c start to end.

Like I said, try it at 65 deg C. Set the Adaptive Fan target to 65, and recalibrate. I don't think I've ever seen a DSMC maintain a temperature of 46.

 

[Robino_J]

Like I said, try it at 65 deg C. Set the Adaptive Fan target to 65, and recalibrate. I don't think I've ever seen a DSMC maintain a temperature of 46.

thanks Eric I will try that. Only thing is I think it is at adaptative 65c target - isn't it the default? I have not touched it.

With 65c adaptative target my sensor goes up to 46~48 and core goes to 65c (from recollection) I will check when I come back later.

 

[David Battistella]

I would say turn the camera on, let it warm up for 10 minutes.

Set fan settings to adaptive 65 degrees.
Set your fps shutter, etc.
When its up temp. Black shade.

ive found it holds temp even on timelapse shots that last many hours.
Check also that your fans are working.

 

[Robino_J]

I would say turn the camera on, let it warm up for 10 minutes.

Set fan settings to adaptive 65 degrees.
Set your fps shutter, etc.
When its up temp. Black shade.

ive found it holds temp even on timelapse shots that last many hours.
Check also that your fans are working.

EDIT: Nevermind - I think you meant the core temp to be 65c...

OLD POST RESUME >

so my camera has been powered for 20 minutes set to Adaptative at a target of 65c and the sensor temp won't go over 47. Core is at 64. Current ambient temp in the room is approx 79f

What should I do?

see pic

 

[ericyoung]

OK. We were thinking you meant the core temperature you were using was 46 deg C.

So it looks like you had the default Target Temp of 65 deg C already, and as expected the Adaptive is maintaining the core at 65 deg C more or less. The way your camera is behaving definitely doesn't seem right then.

Don't know what else to suggest. It's probably time to contact your Bomb Squad rep.

 

[Robino_J]

OK. We were thinking you meant the core temperature you were using was 46 deg C.

So it looks like you had the default Target Temp of 65 deg C already, and as expected the Adaptive is maintaining the core at 65 deg C more or less. The way your camera is behaving definitely doesn't seem right then.

Don't know what else to suggest. It's probably time to contact your Bomb Squad rep.

Yes sorry about that. I'm blackshading again maybe last time it was not exactly at 65c?? If it's still bad after my new blackshades I will send the camera in.

 

[Robino_J]

OK. We were thinking you meant the core temperature you were using was 46 deg C.

So it looks like you had the default Target Temp of 65 deg C already, and as expected the Adaptive is maintaining the core at 65 deg C more or less. The way your camera is behaving definitely doesn't seem right then.

Don't know what else to suggest. It's probably time to contact your Bomb Squad rep.

I re-blackshaded everything. I did another time-lapse at 1/2th and if the sensor temp is not exactly at 47c (my new sensor temp target is 47c - core is 62~64c) the color shift is terrible. The time-lapse covered from 45c to 49c.

Then I did another time-lapse but using 1/48th calibration and ran it from 45c to 50c and I could see a tiny shift mostly in the shadows but i guess that's expected when your T is 2 degrees off. This tiny shift is acceptable though. The 1/2th is not.

OPTIONAL If anyone want to try since some users stated that this was happening to them as well... here's how I test the 1/2th calibration / time-lapse.

1. Blackshade 1/2th when core temp is at 65c and set camera to this calibration.
2. Make sure your temp is at your target sensor temp (for me it's 47) and then lower the temp by setting fan mode to manual. I put it on manual for 5-6 seconds and it lowers the sensor temp to around 44~45 - Do this until you reach a lower temp (around 2 degrees off from your target sensor temp) and then put the fans back to adaptive 65c.
3. Put your FPS to 1 and start recording the time-lapse at the lower temp until it reaches the target temp. Then you want to make it go hotter so set the fan adaptive target to something like 75c
4. Check the time-lapse to see if the colors are shifting in a non-acceptable way.

On my camera, going 1 degree off my target sensor temp is not forgiving and the footage becomes unusable. Basically the blue channel crushes.

 

[ericyoung]

What happens if you just use the calibration at 1/48th shutter speed, but do the time-lapse at 1fps?

 

[Robino_J]

What happens if you just use the calibration at 1/48th shutter speed, but do the time-lapse at 1fps?

It looks fine. Very small shift from 45c to 50c (with 47c sensor target)

 

[Graeme Nattress]

Best recommendation for longer exposures is to build them out of shorter exposures via the frame averaging. You can average up to 16 frames which makes for extremely low noise images too.

Graeme

 

[Robino_J]

Best recommendation for longer exposures is to build them out of shorter exposures via the frame averaging. You can average up to 16 frames which makes for extremely low noise images too.

Graeme

Graeme, so what I'm experiencing with 1/2th exposure calibration is normal right?

This video shows how sensitive the calibration is when the sensor temp change from it's nominal target to +2 degrees. You can see the image loosing calibration even with 1 degree off.

Just want to know if I should send the camera in or if that is expected. I tried frame averaging yesterday and i'm not sure it will work for my needs. I shoot miniatures and the motion blur has to be very accurate. I do need to learn more about it though - new to this average processing.

https://vimeo.com/130215986
Password: bs

 

[Graeme Nattress]

Low shutter speeds will make everything very sensitive to change, and temperature matching with black level calibration is going to be one of those sensitive factors. Any issue here will be magnified by high ISO shooting.

A long exposure (even when bang on calibrated) won't reduce noise any more than a proper exposure reduces noise. Frame averaging does vastly reduce noise though, so there's benefits to using it over-and-above just what a long exposure can achieve for you. Similarly it makes the system less sensitive to any calibration change and enables very high ISO shooting. For motion blur you'll have to experiment to see how it works for you.

Graeme