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  1. #1

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    Dev by inspection: what light?

    I've got this [font=Arial, Helvetica, sans-serif][size=-1]Kaiser 'Spectral 590' Safelight [/size][/font]in my darkroom that can be used for color work:
    [font=Arial, Helvetica, sans-serif][size=-1]...The light emitted lies in the narrow spectral range around 590 nm...[/size][/font]
    I wondered if it can be used for development by inspection. Is it in the safe range for film and, if not so, what lamp should I get for it?

    Don't try to sell me IR and nightvision goggles, I know that story ;-)

    Tnx.

    G

  2. #2
    Amund's Avatar
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  3. #3

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    dark green, the darkest of them all ...

  4. #4
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    With the SBR's working as well as they do, I can't imagine doing DBI. tim (curmudgeon, to be sure)

  5. #5

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    Quote Originally Posted by noseoil
    With the SBR's working as well as they do, I can't imagine doing DBI. tim (curmudgeon, to be sure)
    Let's just say I'm curious and want to try it at least once.

    G

  6. #6

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    I use a red safelight filter with a 15w bulb. The light is about 6 feet from my developer tray & pointed away. I use TMY in pyrocat. It is a bright light, but I don't notice any fogging happening. I'm guessing the film is desensitized as it develops, but I don't know that for sure. I have fogged some film by accident once when I stepped on the footswitch while the film was in the presoak. I do use time & temp, but like to check my negs anyway. Sometimes I'm glad I did.

  7. #7
    Ole
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    In the spring and summer, I use white light. My darkroom is sufficiently "un-dark" that I can see what I'm doing after about five minutes in the "dark". Haven't seen any fogging from this, although I limit the time out-of-developer as far as possible.

    When the daylight is less than 18 hours I prefer to work at night, with a dark green filter. Or dark red if I'm doing EFKE PL25, since it has reduced red sensitivity so I can use a relatively brighter light. But it's still pretty dark!
    -- Ole Tjugen, Luddite Elitist
    Norway

  8. #8

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    Go to K mart or some similar store and get a a green glow night light, the kind that plugs to outlets to keep your home lit enough for safety at night. These things are about 4 wattts in power and emit quite a lot of light and since they are leds, the spectrum of light they output is very narrow. Result: no fogging, ever, that I have noticed.

  9. #9

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    When developing by inspection the film should not be exposed to the safelight until at least half the development time has elapsed. Exposure should be brief and the safelight should not be closer than 3 feet.

    A dark green safelight such as a Wratten #3 should be used. This corresponds to the greatest sensitivity for the human eye and usually roughly corresponds to a dip in the film sensitivity.

    Some practice is required before this method becomes an accurate means for determining development. The extent of development should be gauged by inspection of the film from the backing side and not from the emulsion side.

    Some desensitization occurs from developer by-products which occur during development. However, the film can be desensitized by first soaking in a dilute dye solution. Two commonly used solutions are given below.

    Basic Scarlet N Desensitizer

    Stock Solution

    Distilled water (50°C) ................. 175 ml
    Chrysoidine .............................. 1.0 g
    Phenosafranine* ....................... 1.0 g
    Isopropanol .............................. 5.0 ml
    Distilled water to make ................ 200 ml

    * an equal weight of safranine O may be substituted.

    For use dilute 1 part of the stock solution with 50 parts of water. In total darkness, soak the film in the bath for 2 minutes and then transfer to the developer without rinsing.

    Ansco 351 Pinakryptol Green Desensitizer

    Stock Solution

    Pinakryptol Green ...................... 1.0 g
    Distilled water to make* ............... 500.0 ml

    * Use of a 50-50 water-alcohol mixture for solution will improve the keeping
    qualities of the desensitizer.

    Dilute the stock solution with 10 parts of water and follow the instructions given above.

    The dyes can be obtained from chemical supply houses or from companies specializing in photo chemicals.

  10. #10

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    Gerald has the right answer. Some of the others, well I'd be sceptical. I've done DBI, but couldn't divine any useful information from what very little I could see. It might be useful if you are doing individual sheets in trays. It is practically useless with roll film on a spool unless you unroll some of the film and look at the emulsion side - a practice that could all to easily lead to some damage if you are not VERY careful.



 

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