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  1. #11

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    I've been using a kodak #13 safe light filter for color printing for over 20 years (the round one that fits in a round safe light lamp). You just have to keep it a safe distance from the paper. As Allan said, it takes a couple of minutes for your eyes to adjust though. When you first turn the light off, it seems like total darkness. Even after your eyes adjust, you can just see well enough to make out the shapes of things in the room. IMO, it beats working in total darkness.

  2. #12
    RH Designs's Avatar
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    Colour papers have a "dip" in their sensitivity curve and safelights designed for colour materials exploit this. However, "safe" is a relative term and with the advent of the very fast RA4 materials it's not really possible to make a truly safe safelight. The amber LED ones (like our own) can be used for brief bursts (to see where you are) but if you want the light on continuously the safe light level is so low that you might as well be in darkness anyway. When I printed colour in my Nova processor, I used to switch the light on only when moving the print from slot to slot so the total exposure was never more than a few seconds. The safest colour safelights use a sodium lamp which has a very narrow spectrum matched exactly to the paper's sensitivity dip but even then, they can only be used at a very low level.
    Regards,
    Richard.

    RH Designs - My Photography

  3. #13

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    The safest colour safelights use a sodium lamp which has a very narrow spectrum matched exactly to the paper's sensitivity dip but even then, they can only be used at a very low level.
    Exactly: Using this type of illumination gives the max. preformance though I use this darkroom light 1,5-1,8m from the baseboard indirectly illumination and dimmed with the mechanical diafragm till 5%.

    Then you have rather visible light but RA-4 proof for about 4-5 minutes which is not a real problem because I am working with a Thermaphot ACP processor so the time between paper on the baseboard make the exposure and put in the developer machine is rather limited.

    Best regards,

    Robert

  4. #14

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    I agree with Robert. Both the DUKA 10 and 50s exploit this spectrum dip. Illumination even at 5 is remarkably good - good enough to cut 10x8 paper into 2 x 5x8s if your trimmer is already set up with guides for this.

    I use drum processing so have never tried it for tray or Nova slot but I suspect it would work OK. From box to exposure and full development in the slot, followed by stop and blix should be way less than 3 mins.

    The two drawbacks are: expensive to buy and replace the bulbs and you can't turn the light off due to the time it takes to warm up again and get to the right spectrum dip. You can however mechanically shield the light with a slide on the outside of the lamp or construct a cover which fits over the lamp. This will cut out the light completely whereas the mechanical cover just reduces it to very low levels.

    I wouldn't be without one.

    pentaxuser

  5. #15

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    Quote Originally Posted by RH Designs View Post
    Colour papers have a "dip" in their sensitivity curve and safelights designed for colour materials exploit this. However, "safe" is a relative term and with the advent of the very fast RA4 materials it's not really possible to make a truly safe safelight.
    What RA4 materials are you referring to? I still use a #13 Kodak filter with Endura and Fuji CA papers. As long as it's a safe distance from the paper, it's a "truly safe safelight". As a test, I left a half covered piece of paper face up on the base board for 20 minutes with the safe light on, and it processes totally white, with no indication of which side was covered and which side wasn't.

    Quote Originally Posted by RH Designs View Post
    The amber LED ones (like our own) can be used for brief bursts (to see where you are) but if you want the light on continuously the safe light level is so low that you might as well be in darkness anyway.
    In my experience, that is not correct at all. I use a 20w bulb with a #13 filter, and it seems almost like total darkness at first, but after a minute or so, it's significantly different than total darkness.

    Quote Originally Posted by RH Designs View Post
    The safest colour safelights use a sodium lamp which has a very narrow spectrum matched exactly to the paper's sensitivity dip but even then, they can only be used at a very low level.
    Sounds like typical advertising hype to me. It doesn't make any sense when you consider that a good quality filter only allows a very narrow spectrum to get through (a significantly narrower spectrum than a sodium lamp produces), regardless of how broad of spectrum the light source produces. A Kodak #13 filter only lets through a "very narrow spectrum matched exactly to the paper's sensitivity", and it's a fraction of the cost of LED or sodium lamp safe lights.

  6. #16
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    We are picking up a very old thread here, but what is being discussed is still relevant. When I did colour printing I used a sodium lamp, which gave a very bright working light. The drawback of this type of unit is it's long warm up time before it becomes safe, and the fact that it should not then be turned off until the end of the printing session. My unit had a mechanical shroud for dimming the lamp, which was a bit of a fag to use. These units were very expensive, but can now be had very cheaply via eBay. Since then as now I used drum processing my paper was never exposed to the safe light for much more than 30 seconds.
    Regards Dave.

    An English Eye


  7. #17
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    Sean;

    No safelight is safe with color film due to the distribution of the sensitivity. However, a Wratten 13 safelight is usable with color paper. The paper is designed to have a hole in the sensitivity where the WR13 emits allowing use at 4 ft or greater with a 15 watt bulb by indirect illumination.

    PE

  8. #18

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    I also used the Kodak #13 (5"x7") filter for a number of years and never experience fogging w/Kodak materials. I used a 7.5w bulb though, with white trays. It was a few minutes in the dark before I could see the trays.

    Regards,
    Paul
    "Pictures are not incidental frills to a text; they are essences of our distinctive way of knowing." Stephen J. Gould

  9. #19

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    A sodium lightsource (590nm) has a bandwith of about 6nm, a mercury lightsource 254nm often used in the spectroscopy also such a small bandwith. Everybody who has worked in that field knows that a real grid (monochromator) with deuterium lamp has a much smaller bandwith than with any filter unit you can build.

    Going to the electronics: A standard LED can have a bandwith of 50-60nm. Especially the Jobo light source has selected LEDs in their lightsource to minimize the bandwith of about 30nm which is five times worser than the sodium light source with the monochromatic light.

    More bandwith means less allowed intensity of the light so a filter unit must be rather dimmed, a LED source in between and the monochromatic light can have the brightest intensity. Fortunately at the moment you can catch these Osram Duka 10 or DuKa 50 light sources for a bargain but indeed you have to be lucky with the bulb itself because they are rather expensive (about Eur. 90-100,- ).

    My 2c on this subject.

  10. #20
    Dave Miller's Avatar
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    Quote Originally Posted by Fotohuis View Post
    A sodium lightsource (590nm) has a bandwith of about 6nm, a mercury lightsource 254nm often used in the spectroscopy also such a small bandwith. Everybody who has worked in that field knows that a real grid (monochromator) with deuterium lamp has a much smaller bandwith than with any filter unit you can build.

    Going to the electronics: A standard LED can have a bandwith of 50-60nm. Especially the Jobo light source has selected LEDs in their lightsource to minimize the bandwith of about 30nm which is five times worser than the sodium light source with the monochromatic light.

    More bandwith means less allowed intensity of the light so a filter unit must be rather dimmed, a LED source in between and the monochromatic light can have the brightest intensity. Fortunately at the moment you can catch these Osram Duka 10 or DuKa 50 light sources for a bargain but indeed you have to be lucky with the bulb itself because they are rather expensive (about Eur. 90-100,- ).

    My 2c on this subject.
    I concur with this. My sodium unit was bright enough to allow me to read instructions, and books by. One other problem, and the reason I stopped using it for monochrome work was the amount of heat it gave off, quite considerable, and a problem in the summertime.
    Regards Dave.

    An English Eye


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