Using coloured lighting to facilitate a black and white grade

[Sherwin Akbarzadeh]

Hi All,

 

I'm shooting a black and white short film on digital. I will be shooting in color to capture the most information and allow flexibility in the grade. This led me to an idea - if I were able to light parts of my scene in fairly uniform colors it would help me to isolate those areas in the grade.

 

My problem is that the main location is a huge warehouse with 10 feet high pure white walls. There are windows near the roof and at one end of the warehouse which bring in a medium intensity soft ambient light. There are artworks hanging on the wall and each artwork will be accented by a 30w tungsten fitting. My thought was that if I used blue bulbs in these fittings, which more or less correspond with the blue ambient daylight also lighting the wall, I could isolate the wall in post and darken it / recover detail in the white wall. I'm shooting on the Sony EX1 into an Atomos Samurai 10-bit 4:2:2 recorder which delivers Pro Res HQ files that grade quite well.

 

On a different but related note - I know about the use of orange or red filters in b/w photography. I would rather retain color information than use a filter on the lens but it got me thinking about whether adjusting the white balance to warm everything up would have the same effect on contrast as using an orange filter. Would skies be 1/3 stop darker with wb set at say, 7000K? It seems like an extreme thought.

 

Thanks

[David Mullen ASC]

No, just changing the color temp is not the same thing. A color filter cuts wavelengths of the complimentary colors while letting similar colors get through, changing the relative exposures of each color on b&w panchromatic film. You are better off getting maximum color separation (like by using Polas outside to make the blue sky more saturated) and then playing with the individual RBG levels in post.

[Sherwin Akbarzadeh]

Thanks for your response David. I see now that maximum color separation is the sensible choice.

 

I'm letting go of my idea about lighting the wall blue. Whilst helping to grade the blue wall separate from the foreground, the blue hue will limit the color information within the wall and thus my ability to grade details in the wall itself.

 

Sometimes it helps to write things out! Thanks for your time.