How to monitor Raw clipping?

[dbauch]

Hi,

A couple of questions for seasoned Alexa Mini users:

1. What is the best way to make sure that raw data is not clipping? As i understand it false color and Zebra monitor the selected color output. So if I'm monitoring in REC 709 then False Color isn't showing me the full exposure range of the raw file.
Do people set up a shortcut to change the viewed color space to log C, so that anything clipping there will be clipping in the raw file?

2. Pixel Masking; Assuming that this is to mitigate fixed patter noise, like Red Black shading. Do I need to do this only once or before every shoot? Is it a pain to do? Is FPN an issue with Alev III?

3. Is there a sleep mode on the mini to save power? Is it more power efficient to leave the camera running than urn off and reboot? Obviously this is dependent on the length of the 'breaks' but in general is there a big power hit from rebooting?

Thanks

[Jan Heugel]

Dear Dominik,

ad 1)
My personal recommendation is to look at a Log C image with False Color applied.
When doing so with Rec 709, you will see clipping where there is clipping in Rec 709 whereas Log C or MAX/ARRIRAW still show details.

ad 2)
If there was a fixed pattern noise, you would not be able to correct it but be more likely to call a ARRI Service Center.
From our experience you only need to do a UPM if you see unwanted effects in e.g. high ISO situations or long exposure times.
To a test before you shoot, if you are fine, no need to do anything.

ad 3)
There's no sleep mode, the camera is always "mission ready".
I'd say as a rule of thumb do only power off if you are on a tight "power base/battery supply" or if you have brakes of more than 5 min. Most occasions I've seen they wanted the camera running because of actor's positions/rehearsals.

Best,
Jan

[Michael L]

Hi,

I agree with dbauch that it would be great to see a raw clipping like a false colour option. I was under the impression that the classic alexa's you are able to view false color on the log-c file?

The Rec709 technique is not great when you want to expose a little higher the fill out your shadows or mids and you don't know what your highlights are doing. Its a little bit like saying just drive slower because your speedometer isn't correct. Yes you can but guessing is not fun.

I use a SmallHD monitor for false color and waveforms in Rec709 and one thing I find frustrating is you can't see your highlights on the waveform because the camera information on the screen effects those readings and clips the waveform. Is there anyway to turn the text brightness down on the screen or make it a different color so it doesn't effect the waveforms?

Thank Michael

[Jan Heugel]

Hey Michael,

that's what I was referring to under 1): monitor your image in Log C and apply false color to that signal.
That gives you an exact view on what the MXF/ARRIRAW will hold and whether there's still detail in the blacks/highlights.

I'm afraid there's no option to change the color of the overlays (only framelines).
The only way would be to monitor the signal with "SDI image = clean"

mini_sdiprocessing.png

Best,
Jan