greg_nixon2 Posted March 19, 2019 Share Posted March 19, 2019 I have some wide aero film which I plan to slit down in width. In the darkroom I would like to be able to see the slitter and film while it is being loaded. The spec sheet for the film specifies "for a short time an indirect safelight of a 15 W bulb with the Agfa 108 filter can be used at a distance not less than 150 cm." What is an Agfa 108 filter and are there any equivalents out there. Cheers Link to comment Share on other sites More sharing options...
Alan Marcus Posted March 19, 2019 Share Posted March 19, 2019 Panchromatic film can tolerate a dim green filter used for just fraction of a minute, during developing. They are used mainly to find lost items in the darkroom or to otherwise help you get your bearings. They are used to observe film in the final stages of developing. We are taking about developing by inspection. This works because wet film has reduced sensitivity and Pan film is less sensitive to green than the other colors. Kodak and most other film makers publish data on a green filter. Likely the Kodak equivalent will be Kodak #3 Dark Green – used to inspect Pan Film must be 4 feet from film illuminated by 15W household light bulb. Restrict safelight operation to just a few seconds. Link to comment Share on other sites More sharing options...
greg_nixon2 Posted March 20, 2019 Author Share Posted March 20, 2019 Thanks for your reply Alan. The keyword is green, I will look for a green filter. I did not know about reduced sensitivity when wet. Link to comment Share on other sites More sharing options...
rodeo_joe1 Posted March 20, 2019 Share Posted March 20, 2019 I think you're better off building some sort of jig that can be used in total darkness Greg. Any safelight that's actually safe for extended use is going to be exceedingly dim, and near to useless for a precision operation like slitting film. When I needed to cut down some sheet colour materials, I used thick adhesive tape as a guide on a small guillotine and butted the sheets up against it before cutting. It was pretty easy to use in total darkness - and I still have all my fingers to prove it! For slitting rolls of film efficiently you need a roller cutter placed the necessary distance from a vertical guide plate. A pair of scissors wielded in near-darkness isn't a good idea.:rolleyes: Link to comment Share on other sites More sharing options...
conrad_hoffman Posted March 20, 2019 Share Posted March 20, 2019 The dark green filters, properly used, are so dim as to be nearly worthless. I think it isn't so much that the film is less sensitive there, but that the eye is more-so. If you're older, like me, your pupils won't open up as far in the dark, making the problem worse. Definitely consider rodeo_joe's suggestion. Link to comment Share on other sites More sharing options...
Alan Marcus Posted March 20, 2019 Share Posted March 20, 2019 You can use infrared. Procure surplus army night vision goggles. Both film manufacturing and photofinishing use IR vision aids for various tasks including film slitting. Link to comment Share on other sites More sharing options...
James G. Dainis Posted March 20, 2019 Share Posted March 20, 2019 If you do use the green safelight, stand in the dark for at least five minutes to attune your eyes to the dark. I once covered a window by a sink with a folded blanket to block the light. All was totally black as I started processing some 8x10 inch Ektachrome. After about five minutes I realized that it seemed a lot lighter. I could have read the New York Times in there. No harm was done to the film. I believe it was Alan Marcus who informed me that the dark green blanket worked as a green safelight. James G. Dainis Link to comment Share on other sites More sharing options...
Alan Marcus Posted March 20, 2019 Share Posted March 20, 2019 If you do use the green safelight, stand in the dark for at least five minutes to attune your eyes to the dark. I once covered a window by a sink with a folded blanket to block the light. All was totally black as I started processing some 8x10 inch Ektachrome. After about five minutes I realized that it seemed a lot lighter. I could have read the New York Times in there. No harm was done to the film. I believe it was Alan Marcus who informed me that the dark green blanket worked as a green safelight. Sorry -- Not me -- Alan Marcus -- IR scope his best bet! Link to comment Share on other sites More sharing options...
glen_h Posted March 20, 2019 Share Posted March 20, 2019 More specifically, it is the sensitizing dyes that (mostly) wash off the grains by about half way though development. That, and as above, the (dark adapted) eye is more sensitive to green. In all the years, I have never been interested in trying this. I now have, thanks to the previous owner of the house, an 8x10 #3 safelight and filter. As I understand it, the #10 is even darker (and has a different use). The OP did not indicate that it was only (and at least half way though) development where the filter could be used. I did one time try slitting film in an ordinary paper cutter. I put electrical tape at the width that I wanted, so I could press against that. (I also have it for the desired print widths.) I slit some 70mm film down to 120 size, in the dark, without any problem. -- glen Link to comment Share on other sites More sharing options...
glen_h Posted March 20, 2019 Share Posted March 20, 2019 There are aero films with different and unusual sensitivities, so it would not be surprising to find one with an unusual safelight. The spec. sheet should also give the sensitivity (spectral) curve. -- glen Link to comment Share on other sites More sharing options...
James G. Dainis Posted March 20, 2019 Share Posted March 20, 2019 Alan, if it wasn't you who mentioned the blanket working as a safelight then it must have been that other former Kodak engineer who did so. Was his name Rowland or some thing like that? I would agree that IR would be best.? James G. Dainis Link to comment Share on other sites More sharing options...
greg_nixon2 Posted March 21, 2019 Author Share Posted March 21, 2019 Thanks all for your replies. I am building a slitting jig for use in total darkness. Attaching the film to the takeup reels will be a bit tricky, I was hoping to be able to use a safe light for that. The film will be mounted on the jig, 100ft roll on the left, then the slitting bed in the middle, and then takeup spools on the right. The film will be emulsion side down for slitting and I need only to view the jig for a short time. The data sheet is here https://www.foma.cz/en/foma-air-100. Cheers Link to comment Share on other sites More sharing options...
glen_h Posted March 21, 2019 Share Posted March 21, 2019 The data sheet is here https://www.foma.cz/en/foma-air-100. Cheers Seems to say: Safelights –infrared light or total darkness. I wonder if you could put the roll inside a light proof bag, with the end sticking out (far enough to reach the splice device). Get everything ready, turn out the lights, and remove the bag. Also, most films are opaque enough that, if kept tight on the spool, will protect the rest of the roll. This is one reason for the rem-jet backing used on some films. (Production movie cameras load off such a reel.). I suspect your film doesn't have spool end flanges, but if you added some, you could load with some light, and again ruin the first few feet of film. Throw those away after slitting. -- glen Link to comment Share on other sites More sharing options...
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