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  1. #21

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    Quote Originally Posted by Jim Noel View Post
    I simplified the solution in my 10x10' darkroom. I use the supplied yellow/tan filter over the tube. I inserted black foam core in the vanes to attenuate the light. I have never had a problem with fogging in the 20+ years I have used this light.
    That's basically the point that I wanted to get to, down the road...but I haven't gotten to "never had a problem with fogging" yet.

  2. #22

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    Go with the filter sold by manufacturer. Rosco gels come in large sheets and the code number is printed only in one corner. Depending on where the cuts are made, it may or may not show up.

    I use the gels in green and blue as VC filters for Aristo cold light head using all the grades of each, 1/8 to full. The man who made Aristo heads put me on to it.

  3. #23
    Greg Davis's Avatar
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    I did another safelight test this morning. First, I used a CD as Ken spells out to check for other colors of light. With the vanes wide open, and the Yellow tape filter in place in the bottom, the Red tape filter in the vanes, I saw no color except yellow. Still with the vanes wide open, I exposed two pieces of paper to the safelight, one was flashed before the safelight exposure, the other afterwards. Both showed signs of fog after 3 minutes in the flashed area, none in the borders. Both showed fogging at 7 minutes in the flashed area, none in the borders. My previous test was done in a different darkroom and I cannot guarantee there wasn't a light leak.

    I expect better performance with the vanes fully or partially closed.
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    Did millions of people suddenly disappear? This may have an answer.

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  4. #24
    Ken Nadvornick's Avatar
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    Hmm...

    If the set of filters you are using, regardless of where they came from or what material they are made of, are successfully removing all of the extraneous higher wavelengths above the sodium D-lines doublet at ~589nm, then the only other immediate explanation is that the paper emulsion sensitivity is bleeding over to some degree into that wavelength. Either because it was designed to do that, or it has aged to do that.

    Or something else silly is going on. Like, say, a leaky paper safe. When I did my testing I did take new sheets of fresh paper directly from the box it came in while in total darkness, then held them in a clamshell safe that I also occasionally use to store loaded film hangers, while the Duplex warmed up. I don't really think this is it, but it is a very slight possibility.

    I am now looking for some time here to go down to my darkroom and also repeat the CD wavelength check. Maybe tonight.

    Perhaps my color vision is slightly different than his and I missed the very faint residual green line that 'Sundowner' observed. Since I tested on Kentmere Bromide, which should be blue-sensitive only, I would still have seen no fogging if, as he observed, all of the blue was removed.

    Tests on VC paper (which I haven't done under the Duplex) would be a different story however, if there was some minor residual green remaining. And I do note that if one looks at the Rosco transmission chart for the #19 filter, there IS a very slight transmission of greens. It looks to maybe only be 2-3%. But it's definitely there, if the chart is accurate.

    For the record, of late I've been using only the red LEDs because I got into working with some Slavich graded bromide, and that paper is marked as red-only safe. Then when using MGIV I've just continued with those LEDs.

    Ken
    "They are the proof that something was there and no longer is. Like a stain. And the stillness of them is boggling. You can turn away but when you come back they’ll still be there looking at you."

    — Diane Arbus, March 15, 1971, in response to a request for a brief statement about photographs

  5. #25
    Greg Davis's Avatar
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    My paper is a brand new box of MGWT, the paper is taken from the box, not a safe. PM me your address and I will send you some of the filter material I am using, which is the same stuff in the filters sold by Freestyle and others for these safelights. You can try it out yourself.

    And as I said, I get some fogging when the vanes are wide open after three minutes, but closed down, I get much longer times while still bright enough to work easily.

    I should note that I am using these Kodak instructions to perform the test.
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  6. #26
    Roger Cole's Avatar
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    Defective #19 filter?

  7. #27

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    Quote Originally Posted by Ronald Moravec View Post
    Go with the filter sold by manufacturer. Rosco gels come in large sheets and the code number is printed only in one corner. Depending on where the cuts are made, it may or may not show up.

    I use the gels in green and blue as VC filters for Aristo cold light head using all the grades of each, 1/8 to full. The man who made Aristo heads put me on to it.
    I'm about at the point of trying a fresh filter from Freestyle (or whomsoever retails them) just to see what happens. The sheet of rubylith came in today, though, so I'm going to test that out tonight...and if I still get fogging then I'll know something silly is going on, somewhere, although I don't know what it could be. I've developed an unexposed strip and gotten pristine white, so I know the emulsion isn't just graying over time.

    Also, I never thought of using blue/green gels as cold light filters...that's pretty innovative!

    Quote Originally Posted by Greg Davis View Post
    I did another safelight test this morning. First, I used a CD as Ken spells out to check for other colors of light. With the vanes wide open, and the Yellow tape filter in place in the bottom, the Red tape filter in the vanes, I saw no color except yellow. Still with the vanes wide open, I exposed two pieces of paper to the safelight, one was flashed before the safelight exposure, the other afterwards. Both showed signs of fog after 3 minutes in the flashed area, none in the borders. Both showed fogging at 7 minutes in the flashed area, none in the borders. My previous test was done in a different darkroom and I cannot guarantee there wasn't a light leak.

    I expect better performance with the vanes fully or partially closed.
    I didn't even make it to three minutes; based on what I saw on my very-inelegant coin test, I had near-immediate, sub-1-minute fogging...but I halfway expected that with the green band that I saw. I wish I could get a picture of it; the best I can say is that it looked like a fuzzier version of the sodium spectrum that was linked-to earlier in this thread, excerpting the blue band. I know I don't have light leaks, because nothing has changed in my darkroom except this safelight and heretofore I could leave Oriental out for an hour without a trace of fogging...and that was a long, boring hour, let me tell you.

    Quote Originally Posted by Ken Nadvornick View Post
    Hmm...

    If the set of filters you are using, regardless of where they came from or what material they are made of, are successfully removing all of the extraneous higher wavelengths above the sodium D-lines doublet at ~589nm, then the only other immediate explanation is that the paper emulsion sensitivity is bleeding over to some degree into that wavelength. Either because it was designed to do that, or it has aged to do that.

    Or something else silly is going on. Like, say, a leaky paper safe. When I did my testing I did take new sheets of fresh paper directly from the box it came in while in total darkness, then held them in a clamshell safe that I also occasionally use to store loaded film hangers, while the Duplex warmed up. I don't really think this is it, but it is a very slight possibility.

    I am now looking for some time here to go down to my darkroom and also repeat the CD wavelength check. Maybe tonight.

    Perhaps my color vision is slightly different than his and I missed the very faint residual green line that 'Sundowner' observed. Since I tested on Kentmere Bromide, which should be blue-sensitive only, I would still have seen no fogging if, as he observed, all of the blue was removed.

    Tests on VC paper (which I haven't done under the Duplex) would be a different story however, if there was some minor residual green remaining. And I do note that if one looks at the Rosco transmission chart for the #19 filter, there IS a very slight transmission of greens. It looks to maybe only be 2-3%. But it's definitely there, if the chart is accurate.

    For the record, of late I've been using only the red LEDs because I got into working with some Slavich graded bromide, and that paper is marked as red-only safe. Then when using MGIV I've just continued with those LEDs.

    Ken
    Maybe it's the VC paper I'm using, then; I don't know how green-sensitive Oriental's Seagull VCFB really is, but now that I think about it my splint-print soft/hard exposures - I use Ilford's MG 00 and then the 5 - are actually pretty close to each other, time-wise. Heretofore, the hard exposures were always longer because of the one-stop light loss, and when I printed on Ilford MG-IV the exposures were usually in a 1:2 ratio. Perhaps, then, Seagull is more green sensitive and I have a compound problem. Thoughts?

    Quote Originally Posted by Greg Davis View Post
    My paper is a brand new box of MGWT, the paper is taken from the box, not a safe. PM me your address and I will send you some of the filter material I am using, which is the same stuff in the filters sold by Freestyle and others for these safelights. You can try it out yourself.

    And as I said, I get some fogging when the vanes are wide open after three minutes, but closed down, I get much longer times while still bright enough to work easily.

    I should note that I am using these Kodak instructions to perform the test.
    I was going to move on to that exact Kodak test after successfully completing my ad-hoc coin test; haven't made it that far, yet.

    Quote Originally Posted by Roger Cole View Post
    Defective #19 filter?
    I've wondered that, actually, simply because I found a LOT of information on rebuilding the Thomas with the #19 filter and when I did so I got results that seemed very atypical. Either that, or I'm really much more incompetent in the darkroom than I suspect...and that's an accomplishment!

    I'm going to go in and try a test with the rubylith right now, and see where I get. I'll post some results in a bit...

  8. #28
    Greg Davis's Avatar
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    Do you have both the top and bottom filters? If you are only using the top filters, that may be the source of the problem.
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  9. #29

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    Quote Originally Posted by Greg Davis View Post
    Do you have both the top and bottom filters? If you are only using the top filters, that may be the source of the problem.
    I did have both, yes; I had the red-tape and yellow-tape varieties, with yellow on the inner filters and red in the vanes, if I remember correctly. The inner filter was replaced with the problematic #19 filter and the outer vane filter was replaced with the #27 medium red. I didn't notice much of a difference in the amount of fog/burn with the vanes in any given position, which implies - to my limited understanding - that the #19 filter didn't work very well, and that the #27 filter didn't change much of what the paper saw, even though it certainly made an impact on what I could see.

    I didn't have time to get the paper test done, but I did manage to get the rubylith cut and installed, and I also snapped a couple of quick cell-phone images that didn't distort the colors too much. As it turns out, the light that the rubylith allows through isn't red at all; it's really about as orange as it looks in the following photo.

    Pictured: And I'm not sure what that means.




    In that image, the rubylith is actually sandwiched between two sheets of glass and taped into place so that there are no light leaks; it doesn't look very sealed, but I promise you that it is. The light is surprisingly orange; I figured that it would be much redder...so either I was 100% wrong or I got some non-kosher rubylith. Regardless, it seems to be working because I also managed to catch a very non-scientific CD reflection that shows the sodium bands.

    Pictured: Absence of green and/or blue.




    Since I managed to catch the color bands, I'll try and replace the #19 filter and see if I can show the green band that I've been seeing...and I'll also try the paper test and see if I can make it to eight minutes this time. If not...well, it's back to Square One.

  10. #30
    Ken Nadvornick's Avatar
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    Finally made it down to my darkroom this evening for some visual sodium safelight testing.

    Here's what I did...

    Removed the Duplex from it's correctly configured hanging mount.
    Placed it on a table in a darkened basement at night.
    Turned off all other light sources in the house.
    Removed all filters so only the bare bulb was showing.
    Closed the empty vanes.
    Let bulb warm and stabilize for 60 minutes.
    This bulb is a relatively low mileage sample.
    Made an observation on the bare bulb itself as a baseline.

    Here's what I saw...

    DVDs showed better color bands than CDs.
    DVD movie Mama Mia! hardly showed any colors.
    DVD movie My Big Fat Greek Wedding was much better.
    DVD movie Four Weddings and a Funeral showed excellent color bands.
    Using FWAAF I saw 2 faint blue bands, 2 green bands, and 1 red band.
    The sodium yellow intensity was blinding.

    Here's what I did...

    Covered both slots with a single layer of filter material.
    Filter material was Rosco #19 Fire polyester.
    Filter material was not sandwiched between glass sheets.

    Here's what I saw...

    Both blue bands gone.
    A single reduced green band still visible, the 1 red band still visible.
    The sodium yellow intensity was moderately reduced.

    Here's what I did...

    Covered both slots with a double layer of #19 filter material.

    Here's what I saw...

    Both blue bands gone.
    Both green bands gone.
    One red band still visible.
    The sodium yellow intensity was severely reduced.

    And here's what I think...

    All my original observations were made using the DVD for the movie The Hunt for Red October.* I now see that different discs have very different reflection characteristics. My original observations showed no residual blues or greens through a single layer of #19. Using the FWAAF disc I now see a definite residual green band.

    My original paper fogging tests were made using only pre-threshold-exposed Kentmere Bromide #3 sheets. This should be a blue-sensitive only paper. It showed no fogging even after 30+ minutes.

    Based on what I saw tonight, I now need to try Ilford MGIV VC blue/green paper to see if that residual green band makes a difference. Based on Sundowner's results, I would expect it to fog on the low contrast end to some detectable level when using my single sheet of #19 material. Then I need to try doubling up the sheets.

    For grins I did a Web search for a narrow-width bandpass filter material centered on the two sodium D-lines at ~589nm. Turns out you can get precisely that spec material. But it's ~$200-$350 per 2x2-inch glass squares for scientific usage. Yikes. But if we were rich that would do the trick perfectly...

    Greg, I'm PMing my mailing address as you suggested. If you'd be willing to loan me enough of those other two Rosco filters to cover the upper vanes of the Duplex for a visual check, I'd be glad to return them.

    Ken

    * You know... Red... October... Safelight testing... <Groan..>
    Last edited by Ken Nadvornick; 09-11-2013 at 02:24 AM. Click to view previous post history.
    "They are the proof that something was there and no longer is. Like a stain. And the stillness of them is boggling. You can turn away but when you come back they’ll still be there looking at you."

    — Diane Arbus, March 15, 1971, in response to a request for a brief statement about photographs

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