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  1. #1

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    Safelight filters - Kodak #1 and #2

    I have some new Kodak safelight filters that I want to use with my red LED safelight (for extra protection with VC enlarging paper and slow ortho films).

    I think most people would use the #1 but I've never been quite clear on the following. The #2 is not just a more dense version of the #1. It also absorbs light further into the red spectrum (ie cuts off at higher wavelengths). So assuming I want a given level of illumination, instead of using nthe #1 filter why not use the #2 filter and put more wattage through it? Given the spectral characteristics of the #2 filter shouldn't I be able to put a lot of light through it and therefore light my darkroom with a relatively bright, but safer spectrum? Or should I just use the #1 with less power? To me, logically, putting more light through the #2 filter would be better for good brightness and longer safe times. Not sure though.

  2. #2
    Mike Wilde's Avatar
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    test, test, test. Even with 'standard' arrangements, safe is only a relative term.

    I expose paper with no neg in the enlarger to process to a very light grey tone, then do a routine of dropping a series of coins on the paper almost immediately.

    I then proceed to take them off at 1, 2, 4, 8 and 15 minutes, and then process it.

    I will do this for any change in the safelight(s) regime in the darkroom(s), even as simple as put a new bulb of the same rating of power in the lamp. Old tungsten lamps can dim appreciably.

    For film fog testing with ortho films, I usally can work out a just fogged exposure under the enlarger, by processing it in dektol, etc.

    Then I set a 1/2 x5" step wedge over the film that has been lightly fogged, and leave in in place for 15 minutes or more, before processing it.


    The 1/2 stop step sequence generates patches big enough to read in my densitometer.
    The fogging effect can also be judged visually by printing the neg with the fogged step wedge pattern to see the first wedge that does not increase fogging.
    From the log factor you can work out the longest 'safe' time.

    The fiirst exposure gets the paper repsonse off of the 'toe' of the H-D curve. In this state it is more susceptible to showing any fogging effects.
    my real name, imagine that.

  3. #3

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    I've tested both with my setup and have very, very long safe times. But would have to add quite a bit more wattage with the #2 to get higher illumination so was just wondering if my theory was ok.



 

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