Using B&W film in electric light

[alun]

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Does anyone have any hints regarding exposure compensation when shooting B&W (conventional) film by electric light?

 

I'm guessing that the kind of electric lighting may make some difference, but not too much, and in the past (with moderate success) I have assumed that you can meter as usual using the in-camera meter or hand-held and then open up a stop or maybe even two if possible, on the grounds that I always think that 'electric light probably isn't as bright as it looks' (not very scientific, I know)...

 

Any suggestions/guidance gratefully received.

[Xmas]

It depends on

 

The electric light you are using

The red sensitivity of your film &

The red sensitivity of the meter

 

 

If it is strip light you need the specfication for the phosphors, they vary a lot. Tungsten filement is very red unless the bulb is overrun like a photoflood, when it is still overly red.

Ortho will need more exposure, however lots of the fast films are overly red sensitive well into near infra red where tungsten will be pouring out photons, just like a M8. The film data sheet will tell you this.

The CdS cells are overly red sensitive unless they have a cut filter like M8, Selenium is closer to the eye for response.

 

You might need more exposure or less, you need the specs for every thing to predict which way.

 

Noel

[tgray]

I guess it depends on the film and the 'electric' light. For most panchromatic films, like Tri-X, you can probably get buy with just normal exposure, even if they light is something extreme like all red. Just like shooting in daylight with a red filter on the lens. So you can trust the internal meter.

 

If you want to be real exact, Kodak rates their motion picture B&W film as 1/3 of a stop slower in tungsten lighting. So if you are shooting Tri-X and normally rate it at 400, try 320 indoors or apply an exposure compensation of +1/3.

 

They don't give this correction factor for their still films. They do give different filter factors for filters under daylight and tungsten, but I don't think that was what you were asking. I quote out of the T-Max spec sheet: "Virtually no difference between the daylight and tungsten film speeds"

[alun]

Thanks, both - that last comment (tgray) is helpful as it's T-Max I have. Cheers.