B&W- Setting the right ASA

[Jan Weis]

Imagine this, You are in a building which is lit by sunlight from the outside through windows. Do I set the the film speed as outdoors or indoors. I assume that I should set it as out doors since it is sunlight we're talking about but I want to make sure not to make a mistake after all its my first short film.

 

here's a shot of the set:

 

 

 

 

 

//Jan

[John Pytlak RIP]

If the light source is unfiltered daylight, treat it as daylight. Compared to tungsten light, daylight has more energy in the blue portion of the spectrum. Be careful, as some energy-efficient windows may be "tinted" and have some coloration.

 

Most panchromatic B&W camera films have a bit more sensitivity in the blue portion of the spectrum than the red. So a blue-rich daylight source is a bit more effective in exposing the film, and the film exposure index for daylight illumination is about 1/3 stop faster.

[David Mullen ASC]

Yes, in daylight color balance, whether indoors or outdoors, use the daylight ASA rating.

 

However, note that there is only a 1/3-stop difference between that and the tungsten rating, so it's not the end of the world if you use that rating instead. I also use the tungsten rating when adding any orange-to-red filters, since now the light hitting the film is at that spectrum.

[Jan Weis]

I'm glad it wont be the end of the world if I mess the ASA setting up but I'm even glad that I now know what ASA to set it as and for that I thank you both John & David.

 

//Jan