Daily black shading - risky or not?

[Sean Sweeney]

Hi folks,

Just wanted to get your opinion on something. You get a couple of different schools of thought regarding black shading. RED's recommendations are that you only need to shade after significant temperature variations or very long exposures.

Some AC's have a tendency to want to black shade every morning. Couple of questions regarding this:

1) Is there any inherent risk in a daily black shading?
2) If black shading regularly, are default or current settings preferable (I tend to go with default settings). If setting the shading to the 'current settings', is it not risky over a multi-day shoot (even if the exposure parameters remain the same day-to-day)?

I want to get a feel for what other RED owners / techs / AC's think about that subject.

Many thanks for your feedback.

 

[Dominik Muench]

By "risk" you mean if the sensor could get damaged by doing it to often ? no there isn't.

I'll just quote Mr. Jannard from another tread about the topic:

... you can't do it too often, although it isn't necessary to do it except when installing new firmware, extreme temperature changes, or for very long exposures.

Jim

 

[Sean Sweeney]

By "risk" you mean if the sensor could get damaged by doing it to often ? no there isn't.

I'm thinking more along the lines of having things like color shifts or differences in contrast crop up. I've never seen that even on shows with daily black shades, but I'm curious as to other folks' experience regarding the consistency of the image from day-to-day with daily black shades.

 

[Sean Sweeney]

Anyone else? I'd love to hear about your experiences with daily black shades if that's how you like to work!

 

[Robert Ruffo New]

Hi Shawn!

Along with what we think of as black shading each black shade cumulatively adds dead photosites to a list - these are assigned the color values of neighboring pixels Sometimes DOAs are a false positives. In general, it's pretty rare to have even one dead pixel found on an MX but if you did it 100 times you may have a sensor map with a few too many dead pixels - although at 5K pixels are so tiny that this is unlikely to be noticeable even if you know to look for it. Easy solution to this unlikely problem is just re-install firmware every 100 black shades or so.

Other than that black shading can be done 1000s of times if you want. However, I would say better to do it at the right temperature than often - because an old blackshade is fine, it's all about temp matching.

If black shading is done in truly black conditions (not just a lens cap!) it is always identical at the same temperature, and you know me, and so you know that I have done all kinds of nerdy tests to ascertain this.

The sensor responds differently (but always in the same way differently) as recording time temp is different from Black Shade temp.

If sensor is much colder, blacks might look a little crushed, if it is much warmer then noise can appear. But.. All these things give the same result every time under the same set of input conditions. Where you can have variance is if you black shade at different temps every day, but are shooting in the same temp environment, or if the temp of your environment changes more than 5-8C. However, it's nothing even rudimentary color grading can't easily fix (and likely is not really noticeable even without a grade matching effort)

All this to say, Black Shades are as consistent as you are, and variances are 100% operator error.