Black Shading (again) Strategies

[David Battistella]

Now that there are 4 spots to store Black shading calibrations I am starting this thread to consolidate resources and the discussion. *so as not to derail the other thread too much.

Mark Peterson has an excellent thread on this:

http://www.reduser.net/forum/showthread.php?111628-BLACK-SHADING-For-Dummies-amp-Experts

I have a thread on this:

http://www.reduser.net/forum/showthread.php?117878-Black-Shading-A-look-under-the-hood&highlight=



So let's have the BS calibration and strategy discussion over here.

Battistella





Ability to store 4 Black Shading calibrations is IN the release build!

PS: You can custom name your cal maps when EXPORTING.

1. Create a BS calibration at say 180 degrees 24FPS
2. Export the to an SSD (name it what you like)
3. Load it from the SSD

The name does not show up in the user slot but it does load the calibration.

A nice starting point would be to do this.

Slot 1 180 degrees
Slot 2 360 degrees
Slot 3 90 degrees
Slot 4 11 degrees

With these FOUR calibrations loaded you pretty much can shoot at ANY shutter angle by switching calibrations if you get a cal warning.

SCENARIO. You are shooting at 180 shutter and then switch to high speed and get a call warning.
Go to MENU>SETTINGS>MAINTENANCE>CALIBRATE>SENSOR>SELECT THE CALIBRATION FROM THE LEFT PANE SET (takes about 10 seconds) and you are good to go at your new shutter angle.

Next shot is a 360 degree Timelapse, no problem. Follow the steps above and in 10 seconds you are ready to go with that calibration.

PROVIDED, you prepped the calibrations you want in advance.

I keep some frame summing calibrations on the SSD.

These are NOT transferable between sensors so you have to keep the calibration for each camera on Multicamera shoots.

Any other questions. I am here.

Battistella

Great work guys.

Battistella

 

[Björn Benckert]

Ability to store 4 Black Shading calibrations is IN the release build!

PS: You can custom name your cal maps when EXPORTING.

1. Create a BS calibration at say 180 degrees 24FPS
2. Export the to an SSD (name it what you like)
3. Load it from the SSD

The name does not show up in the user slot but it does load the calibration.

A nice starting point would be to do this.

Slot 1 180 degrees
Slot 2 360 degrees
Slot 3 90 degrees
Slot 4 11 degrees

With these FOUR calibrations loaded you pretty much can shoot at ANY shutter angle by switching calibrations if you get a cal warning.

SCENARIO. You are shooting at 180 shutter and then switch to high speed and get a call warning.
Go to MENU>SETTINGS>MAINTENANCE>CALIBRATE>SENSOR>SELECT THE CALIBRATION FROM THE LEFT PANE SET (takes about 10 seconds) and you are good to go at your new shutter angle.

Next shot is a 360 degree Timelapse, no problem. Follow the steps above and in 10 seconds you are ready to go with that calibration.

PROVIDED, you prepped the calibrations you want in advance.

I keep some frame summing calibrations on the SSD.

These are NOT transferable between sensors so you have to keep the calibration for each camera on Multicamera shoots.

Any other questions. I am here.

Battistella

Great work guys.

Battistella

I dont know if this is allready on the road map but would it not be great if the camera offered us to pick the closest out of the four in camera calibrations that where made when changing exposure time / fps.

For example if I got


1/50s cal
1/200s cal.
then when going from lets say 25fps to 70fps the camera would ask if I want to swap calibration... I don't think doing it automatically would be a good option as it takes some time to swap.

 

[Tommaso Alvisi]

I dont know if this is allready on the road map

I think it is!

 

[David Battistella]

There might be be a few ways.

First. The camera does tell you to swap calibration maps by warning you by turning yellow or red in the T/E indicator.

Perhaps a a calibration might be assigned to a preset. The preset could include the switch to the cal map slot you choose.

The he prest can then be mapped to a single button or say four different buttons for different presets.

1. 180 degree 24fps
2. 360 degree 1fps
3. 216 degree at 60 fps
4. 270 degree at 75 fps

now, you'd assign us BS 1to1 2to2 etc so that when you switch speeds your calibration also switches, 10 seconds.

Battistella

I dont know if this is allready on the road map but would it not be great if the camera offered us to pick the closest out of the four in camera calibrations that where made when changing exposure time / fps.

For example if I got


1/50s cal
1/200s cal.
then when going from lets say 25fps to 70fps the camera would ask if I want to swap calibration... I don't think doing it automatically would be a good option as it takes some time to swap.

 

[Phil Bates]

David, don't you need different black shade calibrations for different ambient temperatures? For example a night timelapse vs studio, etc. I am wondering if this would help if you are shooting outdoors with constantly changing air temp.

Thanks,
Phil

 

[David Battistella]

David, don't you need different black shade calibrations for different ambient temperatures? For example a night timelapse vs studio, etc. I am wondering if this would help if you are shooting outdoors with constantly changing air temp.

Thanks,
Phil

Phil.

BS calibrations are SENSOR operating temperature dependent. I keep mine at at adaptive and 62 degrees (there is a range of course). The fans take care of the rest. The BS warnings come when the operating temp of the sensor out of range for the current camera settings and calibration. You might run into a problem if you can not keep the camera in the range, like the external temperature drops, in which case you'd want to BS at that temperature.

It might change on the same day, as an example, if you shot at the base of a mountain range and ended up at 1200 meters and cooler temperatures later the same day. Some of this also depends on your fan noise. I know Christopher Probst has mentioned he likes to run his dragons cooler, so there the fans would be running higher and louder. If you are doing interviews and long takes you might want to shade it "hotter" so that is stays in range.

Again here. Best to employ a strategy during prep.

Battistella

 

[Phil Bates]

Thanks David!

 

[Tom Van]

...
A nice starting point would be to do this.

Slot 1 180 degrees
Slot 2 360 degrees
Slot 3 90 degrees
Slot 4 11 degrees

...

This made me rethink my BS strategy, or perhaps caused a bit of confusion. I've always thought black shading was dependent on shutter speed, not shutter angle. I have cal maps saved at different shutter speeds...

1/50 @ 24fps
1/100 @ 50fps
1/200 @ 100fps

So the shutter angles are all 180 degrees relative to the frame rate.... have i been doing it wrong? In other words, since I'm switching my cal maps to the same angles, am I making a difference?

 

[David Battistella]

Have a look at this. Its just a different way of displaying relatively the same values. Some use degrees, some use fractions.

http://provideocoalition.com/freshdv/story/shutter_speed_vs_shutter_angle

Battistella

 

[Björn Benckert]

This made me rethink my BS strategy, or perhaps caused a bit of confusion. I've always thought black shading was dependent on shutter speed, not shutter angle. I have cal maps saved at different shutter speeds...

1/50 @ 24fps
1/100 @ 50fps
1/200 @ 100fps

So the shutter angles are all 180 degrees relative to the frame rate.... have i been doing it wrong? In other words, since I'm switching my cal maps to the same angles, am I making a difference?

Shutter speed is whats relevant angle together with a frame rate gives you a shutter speed.

 

[Tom Van]

David, I understand the relationship between shutter speed and shutter angle but I'm a little confused about whether my cal maps make a difference when I'm going from one shutter speed to another while maintaining the same angle... i.e.

shutter speed 1/50 @ 24fps (180 degrees) to shutter speed 1/200 @ 100fps (also 180 degrees).


Edit: I just went over Mark Pederson's BS thread again. It's shutter speed. Cal maps on different speeds but same angles should make a difference. Confusion cleared.

 

[David Battistella]

David, I understand the relationship between shutter speed and shutter angle but I'm a little confused about whether my cal maps make a difference when I'm going from one shutter speed to another while maintaining the same angle... i.e.

shutter speed 1/50 @ 24fps (180 degrees) to shutter speed 1/200 @ 100fps (also 180 degrees).

Depends if you are in relative or absolute mode.

If you don't move off of the 180degrees then you probably won't need to calibrate. if you move to 45 degree shutter you would probably see the cal indicators switch color.

I always use degrees.

Battistella

 

[David Battistella]

A little bit more on RELATIVE and ABSOLUTE modes.


There's a difference between RELATIVE and ABSOLUTE shutter with the DSMC system. Since I am pretty much always in RELATIVE (displaying the shutter angle in degrees), then what happens in that mode is that as I change the shutter or frame rate the camera's exposure time changes. So if I am doing ramping or something, the camera will change exposure through the ramp, it adjusts the exposure time automatically. This way the camera only reports cal errors when I move the angle around say from 180 to 90 while it maintains the optimal shutter. (you get fewer yellow warnings) in this mode.

In ABSOLUTE it's the other way around. The shutter time (1/48th etc) stays the same but the shutter angle changes. If you want to see it in action then you have to fire up the camera and see the effect as you change shutter speeds in ABSOLUTE mode and change ANGLE in the RELATIVE mode. I leave it on RELATIVE for over or under cranking so that the camera maintains exposure, otherwise when ramping from 24-70FPS the image goes darker showing you the stops of light loss because it is maintaining the shutter angle (as much as it can with the electronic shutter).

Basically, in ABSOLUTE mode an specific shutter speed (1/48th) while the angle (exposure time) changes so you have to keep an eye on what the CAL map is doing while you are in that mode. The camera will tell you when it is getting out of range.

Green Green
Green Yellow
Green RED

You can get away with Green Yellow in many cases but Green Red would need a BS calibration.

Cheers,
Battistella

 

[Trevor Meier]

Is there any benefit to separate calibrations for frame averaging/summing? Since the technique sums multiple exposures at a preset exposure time, it seems like that exposure time would only need to be calibrated once whether you use it in summing mode or not... or am I off base here?

 

[David Battistella]

Personally,

I create a new BS for summing and averaging modes because it is a special situation for the sensor. In summing the sensor is taking the sum of a number of exposures (at a given angle ) to create a frame to emulate slower angles and longer exposure times.

With the averaging, the camera is making multiple exposures and averaging the exposure to create a frame.

im experimenting now with using averaging to create cleaner frames. As an example you can use a two frame average (asking the dragon to do 2, 4, 8 or 16 exposures instead of one, to create a frame, which can also apply to regular speed footage. Here the camera sensor and computer combine to computationally create the desired exposure.

Running some tests with this when I'm back in Italy.

In any case.

If you go into summing or averaging mode, I'd say you have to do a BS for any of the settings you select. And one for exact frame number you choose 2,4,8,16 in either of these specialized modes.

Battistella

 

[bevan goldswain]

Has anyone had trouble getting odd RED / YELLOW warnings when using motion mount?

When I have motion mount set to ND ONLY then the T/E warnings respond the samw as if I had any normal mount.
When it is set to SOFT or SQUARE shutter it give yellow or orange warning even when the correct black shade calibration is set.

example:

Motion mount on ND only mode
24fps 1/48 shutter - BS CAL MAP is for 1/50 sec and I am getting GREEN/GREEN for the T/E

Motion Mount on soft shutter
24fps 1/48 Shutter - SAME BS CAL MAP as before, and I get GREEN/DARK YELLOW T/E+

Only when I change my shutter to 1/125 do I get GREEN/GREEN when using soft shutter mode.


Can anyone explain what is going in here?
Why would changing from soft shutter to ND only effect the BS warning?

 

[Ruff]

This is now so confusing for the camera assistants.

I appreciate the additional stored options, but try explaining how to select and change them to an AC on a super busy set... it's a nightmare.

Is there a reason why the camera cannot auto select the most suitable stored option?

Diving into the menus every time we change a camera / shutter speed is a burden.

 

[Tommaso Alvisi]

Is there a reason why the camera cannot auto select the most suitable stored option?

It should work this way...let's hope in the next fw update!