Re: Realist and a 70s kmart flash

[bercov@xxxxxxxxxxx (John Bercovitz)]

The problem has been changed from a building and other stationary objects 
to a building and other stationary objects and actors.  Therefore my 
earlier post, which was stated to be for stationary objects, no longer 
applies.  So what can be done now?

Well, the exposure equation has aperture setting, exposure time, 
illumination, and film speed to play with.  Aperture setting and exposure 
time are fixed by the depth of field and by the moving objects.  This leaves 
you illumination and film speed as inversely related variables.  One choice 
for illumination is existing light, which is probably very well done 
because you have no doubt set up your lighting to show off your set and its
actors to best advantage.  Another choice is artificial lighting such as 
strobe, flash, or tungsten lamps.

If you go with existing light, you might try film in the 1000 to 3200 ASA 
range*.  It will be a bit grainy but if you're going to convert to Photo CD 
anyway, the grain may not be as important.  Franklin Flocks and Bob 
Mannle, both of this list, have a great deal of experience in the areas of 
low existing light photography and computer graphics.  Perhaps one of 
them would care to comment on to what degree grain would show up in a 
computer graphic converted from grainy film.  I do think you want to stick 
with print film so that you can utilize the extra couple of stops of 
exposure latitude it has and also to make your exact exposure values less 
critical.  A measurement of the existing light will tell you what film
speed you will need.

If you don't want grain, you'll want to go with 100 speed print film and 
then you'll need artificial lighting (usually expensive ) which you will 
have to buy, rent, borrow, steal or cobble up.  If time is money, cobbling 
up ain't worth it.  A friend of mine used to tell me, "Time isn't money; 
money is money."  But what I mean is you'd likely get your lighting quicker 
if you bought it with the money earned on a night job at Mickey Dee's than 
if you spent your time cobbling up/together flash units.  But you never 
know; at a photo swap meet you might find a few dozen ancient and 
venerable strobes for a few bucks each.  If you can, then I would try to 
mimic the placement and intensity of your existing lighting with the 
strobes.

The other option in artificial lighting is tungsten.  You'll need tungsten 
film and you'll need speed-robbing filters if you can't find tungsten 
sources which match the color temperature of the film.  Common floods 
have a lower color temp but a filter chart from any filter manufacturer 
will tell you which filter you need and how many stops it will cost you.  
If you have a large Powerstat or Variac, you can pump the voltage up to get 
the color temp you need.

John B

PS:
Incidentally, going back to an earlier point your mentioned, to test your 
strobe synch, just point your strobe and camera at a nearby wall, open the 
back of your camera, put an eyeball behind each lens, and trip the shutter.  
If your setup works, you will see a flash of light come through the lenses 
when the shutter is open.  If you see the shutter blades "frozen in time" in 
a partly open condition, you'll know your synch is off slightly.  If you see
no flash of light, you got bigger trouble.

*Film speed is basically another trade off, this time with graininess.  
Since a certain number of photons are required to expose a grain of silver 
halide, regardless of size of grain, if one wants high speed film, one 
should make the presented area of the grain large to give it a better chance 
of intercepting the requisite number of photons.



------------------------------

End of PHOTO-3D Digest 1094
***************************