Omega D2 with point source DM lamp housinggreenspun.com : LUSENET : Large format photography : One Thread
I just bought a D2. It has DM Micro film head. This is a variable intensity point source light. My question is; what kind of results will this yield. What is a point source light and how does it differ from the regular condenser? Any information would be helpful. Thanks Mark
-- Mark Cowart (firstname.lastname@example.org), June 13, 2001
The sun is a point source. A point source enlarger produces very contrasty light that old timers thought of as very sharp. A comparison of point, condenser and diffused enlargers setups by David Vestal concluded that high quality prints could be made with each system, provided negative development and paper choices were tailored to the specific light source. The point source problem, and to a lesser extent condenser problem, is that in addition to producing sharp images of silver grains, they also produce sharp images of fibers, dust, and scratches. I have no experience with a microfilm head, but since such images are theoretically quite small, I would be concerned about coverage of the negatives. If coverage isn't adequate for your negs, it might be best to look for a used head.
-- Steve Singleton (email@example.com), June 13, 2001.
I printed extensively with a similar point-light source enlarger in a commercial photography studio in London. We were meticulous in film-processing to produce dust-free and low-gamma negatives (mostly Hasselblad, some 35 too). Experiment with adjustments to your ISO and development times to achieve a much thinner than usual neg, but be aware that any scratch, abrasion or dust will show up. Instead of stopping down your enlarging lens (which needs to be a sharp one), full aperture is used, and the point-light source is dimmed. Print exposures are still quite brief usually, since the neg is rather whispery and thin. Howevere a unique result is obtainable, with the effect of finely powdered charcoal on white paper, due to the very acute rendition of sharp-edged grain particles. It's some work to get your environment and your processing techniques & habits clean and consistent enough, but the effect can be very impressive when it turns out right. Careful alignment of the stages of the enlarger is also vital, since with lens wide open, there is no forgiveness from additional depth of field, and that grain does need to be critically sharp, not mushy, or the whole point is lost. Good luck, if you decide to try it, and do let me know how you fare with it - I bought a point-light source unit myself a while ago, for similar purposes. Cheers -Rodney Polden-
-- alma (firstname.lastname@example.org), June 17, 2001.