Exp comp for BW film in Artificial Light?

Hello,

I'm interested in using HP5 indoors w available tungsten and fluorescent light, and wanted to know if I need to make any adjustments in metering. Thanks.

GB

Manufacturers used to publish two speeds the main ISO for daylight and another for Tungsten lighting, but a lot depends on the films spectral sensitivity, and the same goes for the light meter.

Ilford used to recommend 400 EI for daylight and 200 EI for Tungsten with HP5 and it does help retaining good shadow details to increase exposure y a stop.

Ian

Take care also, should you use filters, that the filters factors may be different too.

gbenaim said:

Hello,

I'm interested in using HP5 indoors w available tungsten and fluorescent light, and wanted to know if I need to make any adjustments in metering. Thanks.

GB

Click to expand...

As a rule of thumb, I'd cut the film speed in half for tungsten, but only a proper film test will tell.

The amount depends on the film and also on your meter.

The manufacturer's data sheet will give a tungsten speed. If it is a modern film and no tungsten speed is given then no adjustment will be needed.

Some meters are more sensitive to the red end of the spectrum and may cause underexposure. The problem is worse with modern meters with silicon cells, little problem exists with selenium & CdS meters.

Shoot a test roll and bracket and find out what works best for you.

You do need to be careful in one area: household illumination is very uneven. When taking pictures indoors you may need to add lamps or reflectors to fill in the shadows. If you have an incident meter or grey card then you can check the lighting balance by metering both the shadow side and the lit side of the subject - the ratio shouldn't be much greater than 1 stop.

One reason that Tungsten film speeds are rarely given these days is because they were mainly for to Tungsten studio lighting which was once far more common.

So with B&W cine films the Tungsten light EI is given, but not listed for the same conventional stills films.

Ian

Since intended underexposure is somewhat of an epidemic with the 'avialiable light' crowd, I suspect many people would ignore the Tungsten exposure index anyway

The use of different daylight and tungsten EIs were mostly discontinued sometime in the 1960s after the 1961 exposure meter standard changed the color temperature of its calibration light source. Allen Stimson, An Interpretation of Current Exposure Meter Technology, Photographic Science and Engineering, vol 6, no 1, Jan-Feb 1962 states "Among other innovations, meters will henceforth be calibrated at 4700K instead of 2700K to make them more accurate in daylight and eliminate the need of different tungsten speed for most panchromatic materials."

I've attached a copy of a couple of pages from an old Kodak Reference Handbook. It's very interesting.