Thanks! So it sounds like I should be aiming for 5000 K. I plan on using a digital camera to take pictures of the slides once their on the light table. However, I'm worried about a "strobe effect" that I've seen in the past where the light seems to dance around on the lcd of the camera. Is there any way to avoid this?
Hi Jeremy,
The strobe effect is probably the interference between the power-grid frequency, and the LCD refresh frequency. But the intensity of fluorescent tubes does vary, unless one uses some smart circuitry to reduce 'Fluorescent Tube Flicker', and/or the tubes use a slow decay type of fluorescent agents.
Just use a longish shutter-speed if the particular light table exhibits variable emission levels with a short frequency. The nearer your exposure time gets to the frequency of the power-grid in your area (50 / 60 Hz) the more trouble you can expect. If you use more than of half of that, say longer than 1/15th of a second, then the diffused exposure levels will begin to even out. Shooting closeups, and of dense material, at low ISO, with an aperture that benefits the corners of the lens/image, should be possible with relatively stable exposure levels. The light from the tubes themselves is diffused, so the backlight should be rather uniform over the area of a film frame.
Do use a frame mask to avoid veiling glare in the lens, and also shade the front surface of the film from (strong) room light reflections.
Cheers,
Bart
P.S. If you also shoot negative film in addition to your slides, then I'd use differently filtered light to compensate for the mask colour. That will improve noise levels, especially in the blue and parts of the green colors. Also, early Kodachrome was designed to be projected by using lower color temperature lamps than your light table, so they may look too cool and be slightly noisier than necessary, unless filtered light is used for exposure.
