Having taught photography for 30 years, I'll comment on several posts-
On Feb 29, 2008, at 1:06 PM, Richard L. Hess wrote:
Hi, Tom,
The classic approach is two floods at 45-degree angle. You can use
lower-power lamps and with the digicam you don't need to use a filter
like you used to with auto white balance, but beware, you may end up with
more blue channel noise in the digicam image without the filter than
with.
If you don't do a custom white balance, the color of the cover can affect
how the camera "interprets" things
If I were doing a bunch of these, I'd probably set up a tripod with
lights (I don't like the elCheapo copy stand I bought) and put them on
the floor and use my D200 and the 60 mm micro-Nikkor.
I should also comment that you would want a 90 degree finder for any
copystand or other vertical arrangement.
If you are lighting the stuff at 45 degrees look at the edges for
reflections where the cover material wraps around. You can do crossed
polarizers on lights and camera, but the lights will burn most polarizing
material.
45 degree is just a ballpark. A 12x12 mirror tile will be better to
position the light. You also aim them at the far side of the copy, so the
light "feathers" as distance increases.
If you are happy with the colour balance, you can use Chroma 50
fluorescent tubes and that will provide a more even and cooler light.
Again 45 degrees on two sides, but now there are no round hotspots, as
you've got 2' line fixtures which are larger than your target. You may
still see some gradient across between the two tubes, adjusting them
should balance that out. If you get utility reflectors that's probably
better than bare bulbs as it provides more of an option for evening out
the light.
I don't know how many you're doing, but if you're doing 100, it makes
sense I think to get the fluroescents and give them a try. Finding 2-foot
Chroma 50 lamps may be a bit of a challenge, but a good hardware store or
photo store ought to be able to order them for you. I'll bet B&H stocks
them.
Chroma 50 means daylight (5000k) balance. Ideally, a bulb use with over 95
color accuracy rating. I use Philips F32T8/950 thoughout the studio. Best
around last time I looked, and a local bulb store had them in stock.
Nothing is perfect, of course, and even the chroma 50s are a
discontinuous line spectrum, but incandescent lamps create so much heat
and unless you use four, are subject to hotspotting on albums and can't
easily be fitted with polarizing sheets (as they melt). Lower wattage
incandescent lamps (like 75 W or 65 W reflector floods) tend to have
rougher patterns than true photo lamps, and also a lower yet colour
temperature (maybe 2900 instead of 3200 for true, hot photo lamps). The
lower the colour temperature, the more relative noise in the blue channel
as you boost the colour balance in the camera -- that can be overcome by
an 80A filter.
I agree, use a daylight fluorescent if you can't do the work in your
skivvies.
Bruce