Do you HAVE to do a BLACK SHADING CALIBRATION "every time" you start your SCARLET ??

[George D.]

Do you HAVE to do a BLACK SHADING CALIBRATION "every time" you start your SCARLET ??

According to the manual, each and every single day that you turn your Scarlet on to record, you are supposed to do a Black Shading Calibration.

Is this really TRUE ??

I mean, we just got our Scarlet and I'm trying to learn it now, and when I did the Black Shading Calibration, it must have taken 15-20 minutes. You mean to say, we are going to lose that much time, every time we start the camera?

If that's true, shooting in the field from one location to another, is going to be a real drag just waiting for the camera at each location. What if we're driving along and see something great that will last for only a minute or two? Are we going to have to wait for the Black Shading Calibration to happen first?

Please verify that I understand this correctly, and I sure hope I'm wrong.

Thanks for your help.

.

 

[Maik Müller]

No, thats not needed.
Blackshade when:
- you make big changes to framerate/shutterspeed (switching from 4k/24fps to 1k/120fps for example)
- switching to long exposure modes (for timelapse etc.)
- dramatic temperature/environment changes
- on set, before a big shoot
- after you've updated your firmware
- maybe after you haven't used your camera for a few days/weeks

Additional notes:
- Blackshading doesn't take that long anymore with fw 4.
- You can save blackshade-profiles to a SSD (and on your PC), so you can create a library.

And finally, blackshading is a bit overrated, don't panic if you have forgotten it or not the time (as long as you aren't pushing the cam to extremes).

 

[Patrick Grossien]

Also, in youre running the new 4.x firmware, the menu tells you if your black shading is off - also if its off a lot or just a bit.

 

[Nick Gardner]

I black shade when I update the firmware. Thats it. If there are no problems, no need to black shade. No need to fix something that doesn't exist.

Nick

 

[Bob Gundu]

Also when black shading, wait at least 20 minutes to get the camera warmer.

 

[Joseph Kh]

See link below to an old thread explanes when you need to do a black shading calibration. (not sure if this applies to Scarlet and Epic).

www.reduser.net/forum/showthread.php?33809-How-to-do-a-Black-Shading-Calibration

 

[ericyoung]

No, thats not needed.
Blackshade when:
- you make big changes to framerate/shutterspeed (switching from 4k/24fps to 1k/120fps for example)
- switching to long exposure modes (for timelapse etc.)
- dramatic temperature/environment changes
- on set, before a big shoot
- after you've updated your firmware
- maybe after you haven't used your camera for a few days/weeks

Additional notes:
- Blackshading doesn't take that long anymore with fw 4.
- You can save blackshade-profiles to a SSD (and on your PC), so you can create a library.

And finally, blackshading is a bit overrated, don't panic if you have forgotten it or not the time (as long as you aren't pushing the cam to extremes).

All good advice - the only one I don't do is when going to higher framerates from standard 24/25/30fps during a shoot (having black shaded at the start of the shoot at the standard framerate).
Never had a problem.

Dropping more than 5fps below 24/25/30fps, I definitely would.

 

[jake blackstone]

I think the most unfortunate thing about the black shading is it's name. It's really not black shading in a traditional sense, like on a video cameras for balancing three channels for proper black shade. Black shading in Red lingo actually is a FPN correction (fixed pattern noise correction). FPN is present in EVERY modern image sensor and it always need to be measured and taken out electronically. It is very similar to FPN correction, that was needed to be performed in a Spirit telecine every time it was turned on or the gate was changed. As a result, because people don't pay attention to the proper black shading, I get noisy Epic and Scarlet images all the time now, much more so, than even with an old MX. I don't want to start a flame war here, it's just is...

 

[Timur Civan]

start of each day, and when you go from hot to cold. thats a bout it.

 

[Jeff Whitehurst]

George, this info should get you on track. http://www.red.com/learn/red-101/black-shading-calibration

Regarding pulling out the cold camera for a quick shot, I set up my User BS option to be optimized for this scenario. So, Factory BS is for a properly warm brain and standard settings, User BS is for straight out of the bag.
Anything more exotic than that, I take the time to shade for the actual shot settings and conditions.
Hope it helps, Jeff

 

[ericyoung]

I think the most unfortunate thing about the black shading is it's name. It's really not black shading in a traditional sense, like on a video cameras for balancing three channels for proper black shade. Black shading in Red lingo actually is a FPN correction (fixed pattern noise correction). FPN is present in EVERY modern image sensor and it always need to be measured and taken out electronically. It is very similar to FPN correction, that was needed to be performed in a Spirit telecine every time it was turned on or the gate was changed. As a result, because people don't pay attention to the proper black shading, I get noisy Epic and Scarlet images all the time now, much more so, than even with an old MX. I don't want to start a flame war here, it's just is...

It's not just FPN. It's dead/stuck pixels AND noise gradients across the frame. And there must be other stuff too, or the shading wouldn't take so long.

 

[ericyoung]

start of each day, and when you go from hot to cold. thats a bout it.

And cold to hot :smile:

 

[Timur Civan]

well yea i ment both.

 

[jake blackstone]

It's not just FPN. It's dead/stuck pixels AND noise gradients across the frame. And there must be other stuff too, or the shading wouldn't take so long.

"noise gradients" is FPN by the definition. ANY difference between pixels is FPN.
You can't fix dead pixels by electronic adjustment. If that was the case, there would be no dead pixels on any cameras.
It takes that long, because you need to poll each pixel on a sensor and @5K it takes a LONG time to do.

 

[Scott Crawley]

You can't fix dead pixels by electronic adjustment. If that was the case, there would be no dead pixels on any cameras.

I'm curious about that Jake. It has been my understanding that the vast majority of sensors had some flawed pixels and that via software they can be mapped out, otherwise there would be virtually no good sensors at all. I too have been under the impression that a Red black shade included re-mapping bad pixels, though I can not quote a source.

 

[ericyoung]

"noise gradients" is FPN by the definition. ANY difference between pixels is FPN.
You can't fix dead pixels by electronic adjustment. If that was the case, there would be no dead pixels on any cameras.
It takes that long, because you need to poll each pixel on a sensor and @5K it takes a LONG time to do.

As Scott says, I did not mean it was "fixing" dead pixels, it's remapping an adjacent good pixel to that address (or possibly an average of surrounding pixels). For most real world images, a single adjacent pixel mapping is pretty good at hiding the dead pixels, and obviously simpler and quicker than averaging, although it can artifact in certain images. Simply polling pixels can't take that long - after all the Epic can do it 96 times a second!

Your definition of FPN is different to mine. My understanding of FPN - a noise pattern that is stationary in relation to the pixel array, because it arises out of the slight variation of pixel sensitivity and the readout circuitry performance for each pixel. The pattern does not vary with temperature, although it's level and hence visibility does.

A gradient ( as clearly seen on every Epic I've worked with as it warms up - if ISO is turned up ) can be there even if no Fixed Pattern Noise "screendoor" effect is apparent. The gradient is not pixel dependent, but rather due to a temperature gradient across the sensor - almost certainly to do with the particular heat dissipating solution that Red have implemented behind the sensor.

Hence my distinction between the various corrections required to get reference black in the camera during black shading calibration.

 

[jake blackstone]

I'm curious about that Jake. It has been my understanding that the vast majority of sensors had some flawed pixels and that via software they can be mapped out, otherwise there would be virtually no good sensors at all. I too have been under the impression that a Red black shade included re-mapping bad pixels, though I can not quote a source.

Yes, ALL sensors have variations, that needs to be accounted for and adjusted to even out all those variations. That's why it's called FPN. Every sensor has unique FPN and, apparently, it changes depending on a temperature or a readout speed. I think, and I could be wrong, that you're probably thinking about bad hard drive sectors, which ARE taken in account and not used. I'm not aware of mapping of dead pixels, as i'm not aware of a technique of using adjacent pixels instead. Dead pixels is a dead pixel, hence a term "dead pixel"

 

[jake blackstone]

Simply polling pixels can't take that long - after all the Epic can do it 96 times a second!

It takes that long, because it needs to test each pixel at EVERY level, not just a single readout level, that camera does during the shoot. Big diff...

 

[ericyoung]

It takes that long, because it needs to test each pixel at EVERY level, not just a single readout level, that camera does during the shoot. Big diff...

Except it isn't doing that - the camera is capped up, so it only has a black reference. It may well be doing it at every framerate as you suggested above, and that would account for the length of time.

[Edit: or, re-reading your comment, I think that's what you meant! ]

 

[ericyoung]

Yes, ALL sensors have variations, that needs to be accounted for and adjusted to even out all those variations. That's why it's called FPN. Every sensor has unique FPN and, apparently, it changes depending on a temperature or a readout speed. I think, and I could be wrong, that you're probably thinking about bad hard drive sectors, which ARE taken in account and not used. I'm not aware of mapping of dead pixels, as i'm not aware of a technique of using adjacent pixels instead. Dead pixels is a dead pixel, hence a term "dead pixel"

From my days as a broadcast video electronics engineer, mapping of dead pixels is very much a normal technique that was, and is, very much necessary with solid state pixel array sensors since the earliest CCD and CMOS cameras. There are no camera sensors where every sensor put in a production camera is 100% dead pixel free. To do so would mean the yield of usable sensors would be uneconomically low, especially with ever increasing pixel counts. It would also fail to account for pixels that died after camera purchase. Basically the camera signal processing detects the dead pixel and substitutes a copy of the data from the adjacent pixel for that pixel.

We can debate the actual definition of FPN, and and your definition is no doubt perfectly correct in your post production world. However, from my BBC camera engineering world, that is not what we understood by the term FPN. The name itself indicates it's a pattern that is fixed, even if the noise in each pixel is random and varying with temperature and sampling time.