Thread: BLACK SHADING For Dummies & Experts

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  1. #1 BLACK SHADING For Dummies & Experts 
    Okay … there’s WAY too much confusion and incorrect information floating around about Black Shading. Today I even read a post on CML by someone who was talking about a recent Dragon shoot where the camera was warning that “it was going to overheat” - when in fact - it was just the CAL T/E indicator was just telling him that his sensor temp was slightly different than the temp the camera was blackshaded at!! Oh my.

    I'm 100% convinced that lots of folks shooting RED are shooting lots of footage with a non-optimal back shade and many don't even know it. Let’s end this madness now.

    Here’s a guide to Black Shading - OFFHOLLYWOOD style.


    Black shading works by measuring the pattern of fixed noise, storing it in memory, and then subtracting it out of all subsequent frames—leaving only random noise behind. The pattern stored in memory is called a “CalMap” in the RED menus (short for Calibration Map), and is effectively a map of the black level for every pixel—hence the name black shading. - http://www.red.com/learn/red-101/bla...ng-calibration
    Let’s start by focusing on the TWO factors that effect a CalMap - beyond the obvious fact that a CalMap is specific to the actual individual sensor that you calibrate - in other words you would not load on CalMap made on one Epic into a different Epic.

    #1: EXPOSURE TIME (aka Shutter Speed)
    #2: SENSOR TEMP

    When you create a CalMap by blackshading - you can save the file into the camera and/or onto the SSD so that you can copy it to a hard drive and save it. Currently, the latest firmware only lets you hold ONE user created CalMap in addition to the factory default inside the camera. But you can create and save as many CalMaps as you want with different Exposure Times and Sensor Temps onto SSDs - copy to hard drive - copy back to an SSD and load into the camera. Hopefully - soon - we will be able to hold 4 or so CalMaps so that we could switch to another one instantly - wouldn't that be bad ass? :)

    When you look at actual CapMap file - the naming convention works as follows:

    example: 48_45C_20140108080645

    The first digits are the EXPOSURE TIME aka Shutter Speed - in this example 48 for 1/48th of a second. Forget about “Eqivalent Degrees (180 deg., etc.) since that is calculated based on framerate and shutter speed. This is one reason I avoid Equivalent Degrees and like to keep my GUI on Shutter Speed fractions of second as they are absolute.

    The second digits are the SENSOR TEMP in celsius. In this example 45C.

    The next digits in the filename are the DATE (year/month/day) - 2014/1/8 in this example.

    The next digits in the filename are (HH/MM/SS) relating to the 24 hour clock in the camera just to differentiate equivalent calibrations at different times.

    Your back shade CalMap file only cares about Exposure Time - it doesn’t actually care at all about Frame Rates. Sure, when you increase or decrease frame rates you can be forced to increase or decrease your Shutter Speed - but if you black shade with camera at 1/60th of second at 23.98fps with Sensor Temp of 40C - it would be the exact same CalMap as if you black shaded at 1/60th of second at 50fps with Sensor Temp of 40C and the filenames of both CalMaps would start with “60_40C_” - so ... it's all about Shutter Speed and Sensor Temp.

    On the GUI you will see “TEMP: XX/YY” where XX = Sensor Temp and YY = Core Temp.

    Most of the time the Core Temp will be warmer than the Sensor Temp - as the Sensor is closer to the fan/cooling chamber that the Core (guts) of the camera where the processing happens.

    The Sensor Temp is effected by the Core Temp - Core Temp gets warmer = Sensor Temp gets warmer, Core Temp gets cooler = Sensor Temp gets cooler. Think of it as the Sensor Temp “reacts” to the Core Temp.

    Your FAN SETTINGS control the CORE TEMP. So, your “Target Temp” you can set in Adaptive and Adaptive Quiet Record is the Core Temp you want to the camera to level off at and stay at. Adaptive and Adaptive Quiet Record, with the new updated fans, are amazingly fast and efficient at maintaining a target core temp. I stay away from AUTO and MANUAL fan modes.

    The "CAL: T/E" indicator just below the TEMP indicator on the GUI displays the relative change in the temp and exposure times to currently loaded CalMap. The T (Sensor Temp) and the E (Exposure Time) are GREEN when you are “all good”. If one turns Yellow there’s a slight change - if one turns Red there’s a significant change. A + or - will appear to indicate if the Temp or Exposure has increased or decreased.

    DO NOT PANIC if your T turns Yellow during a shot. You are most likely totally fine. However, I try to stay in the green and you should too - and specifically if you are shooting low light - where you might fight the noise floor - you want that Sensor Temp on the money with your CalMap if you want the cleanest image off the sensor. Think of Yellow as "pay attention" and consider a fan adjustment, shutter spped adjustment - or ... re blackshading or loading a pre-created CalMap that more closely matches the T or E.

    If you make a slight adjustment to your TARGET TEMP in your fan settings - you typically will see the Core Temp quickly adjust and the Sensor Temp following. So, as opposed to re-calibrating if your T turns Yellow to get Green on the T in the CAL: T/E indicator - adjust your TARGET TEMP.

    You will see that you can swing the Exposure Time (shutter speed) quite a bit without getting a Yellow warning. But bottom line - that CAL: T/E indicator is gonna let you know when you are pushing it a little - or pushing it too much.

    ALWAYS black shade when you update or re-install firmware and throw out any saved CalMaps you have if you archived any.

    Note that with Dragon especially, it takes a bit of time to warm up the camera. So, best practice is to get your camera crew (or yourself) to power up the camera as fast as possible - ideally while they are building it - so it’s reached it’s Core Temp target and your Cal: T/E gives you all green before you need to roll. If I’m in pinch - I stick in a mag and just let the camera roll non-stop for a couple minutes - I find that it brings the camera up to temp faster. Then I just re-format the card.

    You can pre-create CalMaps for different Sensor Temps by adjusting the Target Temp in the fan settings - let the Core Temp settle to the Target Temp and create the CalMap storing it to the SSD. Then increase or decrease the Target Temp - rinse and repeat. This way, you can have a few CalMaps at different temps and/or extreme shutter speeds so you can load them into the camera from an SSD in a second as opposed to re-calibrating for 13 minutes.

    I hope some of you find this post helpful.
    Last edited by Mark L. Pederson; 01-22-2014 at 10:19 PM.
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  2. #2  
    Senior Member Nick Morrison's Avatar
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    WOW. Amazing. Thanks for taking the time. Very, very informative.
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  3. #3  
    Senior Member Michael Mayda's Avatar
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    Thank you for the very informative notes. Much appreciated!
    Michael Mayda, Forensic Imaging; Dragon #00942; Epic X #00653; Red MX #1976
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  4. #4  
    Member Martijn de Vre's Avatar
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    Thanks!! Very helpful!!
    RED EPIC DRAGON, RED ROCKET X, The Netherlands,Tw @martijndevre
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  5. #5  
    Senior Member jake blackstone's Avatar
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    All this confusion could have been easily avoided, if Red just used a proper name for this process -FPS (Fixed pattern noise) calibration. Term "black shading" is easily confused with standard black shading, that is traditionally done with video cameras.
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    Hi Matk,

    Strong...very strong...STICKY

    Thank you very much

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  7. #7  
    Senior Member Nick Pasquariello's Avatar
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    I have a followup question. On a recent shoot, an AC and I were looking at two Epics, and seeing that the temp was yellow on one (as well as a full 5 degrees Celsius different than the other, despite having had more than an hour of warm-up time each, and same fan settings), decided to blackshade. (Core temp difference could have been due to differing firmware, the cooler one was running the latest v4 stable release, and the warmer one was running the latest v5. [Oh, and for the curious, blackshadeing time between the two firmwares took exactly the same amount of time])

    Anyway, the question: during the blackshade process, the fans run high, and as the camera is shading, the core and sensor temps cooled down considerably. If the sensor is cooling as it's blackshading, (and I'm talking 5-8 degrees Celsius here), is it really getting a good read? And is the shade calibration map based on . . . the temp at the start? Middle? Seeing as how we were shooting interviews, with low fans, I can't imagine that a calibration map while fan is BLASTING on high would be much use 15 minutes into a shot with fans on absolutely minimal . . .
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  8. #8  
    Quote Originally Posted by Nick Pasquariello View Post
    I have a followup question. On a recent shoot, an AC and I were looking at two Epics, and seeing that the temp was yellow on one (as well as a full 5 degrees Celsius different than the other, despite having had more than an hour of warm-up time each, and same fan settings), decided to blackshade. (Core temp difference could have been due to differing firmware, the cooler one was running the latest v4 stable release, and the warmer one was running the latest v5. [Oh, and for the curious, blackshadeing time between the two firmwares took exactly the same amount of time])

    Anyway, the question: during the blackshade process, the fans run high, and as the camera is shading, the core and sensor temps cooled down considerably. If the sensor is cooling as it's blackshading, (and I'm talking 5-8 degrees Celsius here), is it really getting a good read? And is the shade calibration map based on . . . the temp at the start? Middle? Seeing as how we were shooting interviews, with low fans, I can't imagine that a calibration map while fan is BLASTING on high would be much use 15 minutes into a shot with fans on absolutely minimal . . .
    What fan mode are you in? I only use Adaptive or Adaptive Quite Record (with the new Fan Upgrade kits) - and assuming you let the camera settle to target temp and then shade - you should not see a swing of 5-8 degrees. I susepct you are in the AUTO fan mode which I always found problematic. And no two cameras are exactly alike - but remember that the CAL: T on yellow means there's a difference in that camera to the current, loaded CalMap - so if you are comparing two different cameras - do they both have CalMaps loaded that were created at eactly the same Sensor Temp? If not - obvously one will hit green faster than the other. And yeah - different firmware builds can effect different behaviors.
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  9. #9  
    Junior Member Zach Wilson's Avatar
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    Great post Mark. The first thing any noob that starts shoot RED should read.
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  10. #10  
    Senior Member Nick Pasquariello's Avatar
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    Quote Originally Posted by Mark L. Pederson View Post
    What fan mode are you in? I only use Adaptive or Adaptive Quite Record (with the new Fan Upgrade kits) - and assuming you let the camera settle to target temp and then shade - you should not see a swing of 5-8 degrees. I susepct you are in the AUTO fan mode which I always found problematic. And no two cameras are exactly alike - but remember that the CAL: T on yellow means there's a difference in that camera to the current, loaded CalMap - so if you are comparing two different cameras - do they both have CalMaps loaded that were created at eactly the same Sensor Temp? If not - obvously one will hit green faster than the other. And yeah - different firmware builds can effect different behaviors.
    Oh, the comment on the differing temps was just a tangent; we tried to match the cal maps to the temps of the individual cameras, not to each other (in other words, one to, say, 45, and the other to 40). Neither camera has the fan upgrade. As soon as we hit shade, the fans fired up to full bore, for the duration of the shade process, which is what caused the temp to drop steadily throughout passes 1 and 2.

    I want to say that we were in Auto mode. I don't fully remember.
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