Difference between revisions of "Tips for Pulsed Ruby Holograms"
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Latest revision as of 21:55, 11 May 2013
Tips for Pulsed Ruby Holograms
by Ron Michael
When using a pulsed ruby laser and to avoid the waxy look of pulsed ruby reflection holograms try these tips:
A reflection hologram is taken instead of a H1/H2 setup. The person sits further back (A safety requirement of this setup to avoid the reference beam in regards to shooting a direct reflection hologram. Details: Details ).
Together these contribute to a higher demand on spatial frequency resolution of the film. holofringe.xls
This when combined with the playback illumination in effect helps give a smoother image of that person with a small loss of detail.
I use glamor lighting technique to enhance my subject's features. I don't use use a harsh lighting technique but opt for softer fill light in addition to the main light. (This necessitates using a multi beam reflection setup.) Glamor lighting is where a main spot beam is directed from the front, on one side, overhead at a 45 degree angle just enough to cause a slight nose shadow and a second fill light up front, on the other side, similar angle to reduce contrast of the shadows.
If you take pictures underwater with a simple flash camera you get a lot of backscatter from the particles in the water. But at a 45 degree angle lighting technique (similar to glamor lighting) you get the pictures on Scuba magazines. Similar if you pancake light someone you get more of the deeper reflections of the IR lightning. So it's a technique issue as well.
I strived for a natural lighting appearance of the subjects as if it was taken in white diffused light very similar to natural photography, good detail without overt razor sharpness and in using a processing chemistry like SM-6 and a reversal bleach I get the subject playback back toward red-orange for a more brighter playback.
If not careful it's easy to over contrast the image, or pancake light the subject, managed to give them a dead look, able count the pores in the face and yes in that pancake shot get a very waxy look. Yet some ruby work are excellent and remain famous images.
Below is a reflection hologram from a ruby laser without spatial filtering and with a collimated reference beam in a direct reflection holographic setup with two diffused object beams in a glamour lighting technique. Two object beams was split 78/16 percent. Subject is 12 to 15 inches away from film plane. Exposure was single pulse 12nsec at 45 to 60uj/cm2. Film plate is a 30cm x 40cm glass plate Agfa 8E75HD processed in SM-6 and pyrochrome bleach. Two photographs of the same hologram was taken. The hologram was illuminated by HeNe laser. When viewed directly the image appearance was sharp and less contrast and more visible detail. For example you could see the fingers holding the fish.