Portra films under fluorescent lighting.

Can someone correct me if I'm wrong here...

Kodak's Portra data sheet indicates that P400 needs about +2 stop under fluorescent light. An FLD filter also takes 1 stop, meaning I'd want to rate my film at ISO 50 for a correctly exposed and color balanced image? I'd probably want to push to 100 just to recover the speed a bit. I'm aware I need to shoot at 1/60th...

Is that about right? I am shooting portraits in a prison, which is under all fluorescents. I will be able to use a tripod, so I can probably get away with 1/30th of a second, but my fear is that the FL lighting is going to rob me of a ton of light. I can use a small strobe, but my feeling is that the image will just look "strobed" regardless of technique.

Sperdynamite said:

I can use a small strobe, but my feeling is that the image will just look "strobed" regardless of technique.

Click to expand...

If you plan to use a strobe and and FLD filter, I would match the color temp of your fluorescent lights with the strobes. You can also try correcting the image when you print or scan. But don't expect perfect color balance because not all fluorescent tubes have the same color temp. Even if the tubes are the same, the color shifts as the tubes age.

You only need to compensate for whatever filter you are using, so up to 2 stops. The data sheet lists recommended filtration and the loss of light caused by the filtration.

Fluorescent lights flicker on a 60 Hertz frequency [50 Hertz in most places outside the US] so the shutter speed needs to be 1/30 second or slower.