how to shoot in black litegreenspun.com : LUSENET : Large format photography : One Thread
need to shoot second page writing impressions with blacklite, please explain technique.
-- steve williams (email@example.com), December 16, 2000
If I understand what you want to do, is to photograph the impressions of pen/pencil writing on the second sheet of a tablet...when the original has been removed. Sounds like a forensic evidence kind of issue. I'm not sure that blacklight (UV) is the answer...but back lighting may help...or obligue lighting to put shadows into the impressions.
-- Fred Leif (firstname.lastname@example.org), December 16, 2000.
Following up on your email to me, clarifying that UV light causes the phosphoresence you need to photograph, I found the following reference. In Forensic Science, An Introduction to Criminalistics, the authors (Peter DeForest, R.E. Gaersslen and Henry Lee) refer to Kodak Publication M-27 on Ultraviolet and Fluoresence Photography. If you can locate a copy, it may have the specific recommendations that you're looking for. Fred
-- Fred Leif (email@example.com), December 17, 2000.
2 CENTS WORTH......... I have never photographed using black light BUT i have an opinion. In aircraft maintenance there are times when one has to check a non- magnetic part for cracks below the surface and extending to the surface such as an aluminum or magnesium alloy landing gear wheel. The company called Magnaflux puts out a kit and also individual components of the kit and basically this is whats done. The part is stripped of paint using a commercial chemical liquid or gel stripper. It is then washed with water to neutralize the stripper and clean the surface. Then there are 3 spray cans of the magnaflux product; Cleaner, Flourencent Penetrant, Developer that come into play. The Non-ferrous part is cleaned with the Magnaflux Cleaner by not spraying the heck out of it but by spraying the cleaner on a new paper towel such as a Kim-Wype or Wype-all and while the towel is damp, cleaning the areas to be inspected. After a few minutes of air drying the Magnaflux Flourescent Penetrant is LIGHTLY sprayed over the area to inspect and let to 'soak in' for a dwell time of about 15 to 20 minutes. Next is the cleaning AGAIN. The spray can with the Magnaflux Cleaner is used again on a clean paper towel by once again NOT spraying the item being inspected but spraying some onto the towel so it can be wiped by hand. It takes QUITE a bit of towels and hand cleaning at this point. The idea is to get ALL the penetrant wiped clean from the surface and when inspecting is going on, the penetrant that finds its way to any cracks by capillary action will flourese. Back to the cleaning, once the part is cleaned to the naked eye of this penetrant the next and last chemical is used. The Magnaflux product called Developer is used. Its a spray that comes out as a white powder covering the part with a LIGHT coating. Once it dries for a few minutes , it draws the flourescent penetrant to the surface and can be viewed in a room with the lights turned off using the bright 'blacklight' supplied in the kit. My kit ran approximately four to five hundred dollars, the expensive part is the blacklight. The chemicals can be ordered from any large aviation company and the black light can be borrowed maybe on premices from most aviation companies. If you want to experiment with this and modify to suit your needs I can most likely tell you which companies to contact in your area. oooh, one more point. Some gem and mineral collectors can tell you which minerals flourese and you could possibly get some of this material in a powder/dust form to lightly dust over this area for experimenting with this project. Sorry, no ideas about exposure times, but again there are Gem & Mineral Clubs around the country that give slide shows from some of its members from time to time. That may be a possible lead. I wouldn't mind hearing about your final experiment. Good luck and send me an e-mail if i could steer you in a direction for any of these supplies. Miles
-- MILES FEIGENBAUM (MFA1@IX.NETCOM.COM), December 19, 2000.