IRE relationship to F stops when using False Color

[Stewart Read]

Hi All

Can anyone point me in the direction of a good explanation of how the various Purple, Blue, Teal, Green, Pink, Straw, Orange and Red zones relate to F stops ? I know what the IRE ranges of these colours are, but I am trying to understand the f stop difference between (for example) Green and Teal.

Just got the excellent False Colour plug in with the RED preset for Davinci Resolve. Trying to emulate Patrick O'Sullivan's Flanders Scientific/False Color tip in order to analyse shots from movies and understand the lighting ratios !

Thanks for any help !

 

[Mark K.]

False Colour values aren't designed around f-stops, they are spread across variable IRE ranges, so it's best not to think of them in that way. Rather, decide the IRE level at which shadow noise becomes objectionable to you and make that your 'crushed black' reference point. Have a colour set to it. Then set a colour to the IRE range that represents 'shadows with discernable detail', then set a colour for 'middle grey' (which is also a useful reference for approximately 1-stop under caucasian skintone), then a reference for 'correctly exposed caucasian skin', then one for 'skin highlights that you don't want to exceed', then a reference for 'white', then a reference for 'just below clipping', then a reference for 'clipping'.

It's like using the zone system, once you have a reference point for the various exposure levels across a scene - false colour allows you to set precisely the exposure you want almost instantly (it's why it's such a fantastic monitoring tool IMO).

 

[Scott Crawley]

F-stops do not consistently translate to specific IRE values on their own. There are variables at play, so a direct 1:1 comparison is not possible.

 

[Stewart Read]

Thank you Mark

 

[Stewart Read]

Thanks Scott