Safelight for Color

Discussion in 'Color: Film, Paper, and Chemistry' started by Sean, Oct 29, 2003.

  1. Sean

    Sean Admin Staff Member Admin

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    Hi,

    When I took a color class in college I remember having to do everything in total darkness. Was wondering if anyone here has used the new led safelights geared for color? I've seen one by Nova and a few other companies that claim they are safe for color papers. I'd rather do my color in trays by safelight rather than tubes..
     
  2. Eric Rose

    Eric Rose Subscriber

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    As far as I'm concerned there is no such thing as a safe light for color. There are lots of old kreonite ra-4 processors out there for sale. Pick one up and away you go. Processing in 5 minutes from start to dry finish. It's the only way to go. I would not even consider trays, if you have to go manual use the tubes. Less chance of scratches etc.
     
  3. Robert Kennedy

    Robert Kennedy Member

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    I can't even see how a color safelight would work. B/W paper is sensitive to certain wavelengths more than others. Hence the uniquie color of safelights. And even they will fog paper after a certain time.

    But colro paper is sensitive to all visible light. How can that work?
     
  4. Thomassauerwein

    Thomassauerwein Member

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    Sean I know nothing of any safelight for color. Part of the magic of printing color is learning to trust yourself in total darkness doing things viscerally, you'll even be changing the color of the light for burning eventually. I also agree with Eric the less you handle the papers while in the chemistry the less oppertunity for error.
     
  5. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I have a Jobo LED safelight that I use for B&W, and it does have two settings for color. I haven't printed color neg, though, for ages (long before I acquired this safelight) so I don't know how effective it is for such use. When I did print color, I used rotary drums.
     
  6. Ed Sukach

    Ed Sukach Member

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    Me too. I haven't tried it for color either.
     
  7. AllanD

    AllanD Member

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    I have a Durst safelight that is an array of amber LEDs in a rectangular matrix. It gives just enough light to make moving about the darkroom safe, but only just. The down side is that the light levels are so low that it takes several minutes to acclimatize. Turn the room lights on then off, and you are back to struggling in virtual darkness anyway ! Even so, I'd rather work with it than without.

    I did a quick test and it showed no fogging on Fuji CA after five minutes. The light is positioned 2 meters from the paper. I process in an old and rather blackened Nova tank, so the high risk period is (mostly) limited to the time the paper is on the easel. Exposures must be short for RA-4 paper, so I feel that the risk of visible fogging is small.

    I read somewhere that colour safelights only work by limiting the wavelength of light output to a gap in the sensitivity range of the paper. Of course, the characteristics of papers vary, so a light that may be workably safe for one paper may fog another. However, no light will be fully safe; the best one can hope for is that no visible fogging will occur in the time it takes to expose and process.

    I took a chance with the Durst safelight, but with darkroom equipment prices as they are it wasn't a big money gamble.

    By the way, the best thing I did was to buy the Nova processor.
     
  8. Robert Kennedy

    Robert Kennedy Member

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    Interesting. I guess in a way it isn't that different from developing by inspection in theory. You can use XXXX light for XXXXX before it fogs things. Work at a decent clip and you will be safe.
     
  9. OPTheory

    OPTheory Member

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  10. donbga

    donbga Member

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    I agree completely with Eric. Forget the safelight - learn to see with your fingers.

    Processing in tubes is much better than trays but to get best consistency a processor is the way to go. However running a processor isn't a cheap affair be prepared to make a lot of prints to make it worht your while.
     
  11. max_ebb

    max_ebb Member

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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.
     
  12. RH Designs

    RH Designs Advertiser Advertiser

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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.
     
  13. Fotohuis

    Fotohuis Member

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    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
     
  14. pentaxuser

    pentaxuser Subscriber

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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
     
  15. max_ebb

    max_ebb Member

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    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.

    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.

    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.
     
  16. Dave Miller

    Dave Miller Member

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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.
     
  17. Photo Engineer

    Photo Engineer Subscriber

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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
     
  18. panastasia

    panastasia Member

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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
     
  19. Fotohuis

    Fotohuis Member

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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. :wink:
     
  20. Dave Miller

    Dave Miller Member

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    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.
     
  21. Photo Engineer

    Photo Engineer Subscriber

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    Kodak Endura paper was designed with sensitivity to match the output from a tungsten light with a WR 13 over it. The peak and dip were complimentary. This does not apply to Fuji papers AFAIK.

    The WR 13 can be used continuously with an indirect illumination using a 15 watt bulb. I use 2 in my darkroom pointed away from my work area and they are quite bright after just a short time.

    I have never, in over 30 years, fogged a sheet of color paper by that means.

    PE
     
  22. max_ebb

    max_ebb Member

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    I've never had any problems using a #13 safe light with Fuji color paper.

    Exactly what type of sodium lamp are you referring to? Are you sure you're not talking about nominal output rather than actual/total output? If the output bandwidth of a sodium lamp was that narrow, you wouldn't be able to distinguish colors at all in a room lit with a sodium lamp. I assume you're talking about high pressure sodium, but even with low pressure sodium, you can distinguish colors. The same with mercury vapor lighting. I don't know of any unfiltered light source except for a laser that would produce a spectrum bandwidth as narrow as 6nm.
     
  23. Photo Engineer

    Photo Engineer Subscriber

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    Regarding Fuji papers, I did not mean to imply that it would not work at all, but rather that the Kodak papers were specifically designed with that safelight in mind, and vice versa. The Fuji papers may not have exactly that same dye for sensitization.

    PE
     
  24. Discpad

    Discpad Member

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    Low pressure sodium vapor lamps use the sodium doublet transitions at 589.0 & 589.59 nM, and are extremely monochromatic. Only when impurities are added -- Doping -- will you see other electron transitions. :surprised:

    If you go to San Diego, you'll see that all of the street lights are low pressure sodium vapor, installed at the behest of the Mount Palomar Observatory: The "city lights" essentially ruined the southern view of their telescopes; but when the LPS bulbs & fixtures were used, they could easily filter out the monochromatic light contamination.

    High pressure sodium vapor lights also use other electron transitions from the intentional doping; and some even use the very efficient 389 nM near-UV mercury transition, which excites phosphors in the tube much like a conventional fluorescent tube.

    -------

    In any case, although the sodium doublet transition as leveraged in a low pressure sodium vapor lamp is highly efficient, yielding (IIRC) ~140 lumens per watt, it is not favored by illumination engineers because of the very monochromicity which makes it desireable for an RA-4 safelight.