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  1. #21

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    Please do report back on the Durst 138 including and diagrams for constructing the box. Thank you.

  2. #22
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    Maybe make one of the 4 white light with a switch for focusing? Or do you have a different solution for that?

    I might buy an old D2V head for this purpose if I can find one. Any suggestions on what to use for diffusion material that will let through yet diffuse the UV?

    Thanks,

    Will
    "I am an anarchist." - HCB
    "I wanna be anarchist." - JR

  3. #23

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    You will not like this answer.... quartz diffuer.

    UV will pass through Quartz, at almost 100% transmission. Now where to find diffused quartz in a 5-6 inch diameter disck?

    I think you are worrying too much.. get some diffused glass cut to size ( do NOT use plexiglass or other plastic, as it absorbs too much of the uV). You may get some attenuation, but you can still print through it...
    Frank Filippone

  4. #24
    Ole
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    Quote Originally Posted by Frank F
    You will not like this answer.... quartz diffuer.

    UV will pass through Quartz, at almost 100% transmission. Now where to find diffused quartz in a 5-6 inch diameter disck?
    Very easy: Mineral dealers. What you're describing is a slab of dull, boring agate that won't take a colour, and they can't sell do anyone else.

    It doesn't have to be "quartz glass" ( = fused silica), microcrystalline quartz diffuses just as well.
    -- Ole Tjugen, Luddite Elitist
    Norway

  5. #25
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    Quote Originally Posted by Will S
    If I might make a somewhat obvious observation, an enlarger head capable of enlarging to AZO that cost less than a used car (my current vehicle is valued at around $500 for example) would greatly increase the sales of AZO.

    Remember, you give the razor away free and sell the blades...

    Just in case anyone is listening..

    Thanks,

    Will
    I don't think many people want to do that - they want you to buy the "electric" shaver... Especially Kodak. Too bad, AZO was something that I was putting on my "to do" list when I manage to put together a LF rig... but by that time, it will be a dodo bird...
    So I wouldn't hold my breath on that enlarger head. What you put forth is an excellent idea, problem is you are forgetting that we are currently the baby being thrown out with the bathwater...

  6. #26
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    Azo is still very much alive. Buy some and just put it on the shelf, it keeps for a long time without any contrast or fogging problems. No need to do without if you can afford the investment now. tim

  7. #27

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    I had a chance today to make a prototype BLB head for my Durst 138 and it does show that the concept works, but their are some significant problems to solve. I used the bottom of the Durst condensor head as a pattern and cut a 1/4 inch thick piece of aluminum to replace the head. I then made a plywood box to fit over the negative carrier and suspended 4 BLB lamps from a plywood top. The bottoms of the lamps are about 2 inches above the negative carrier and they are quite close together, maybe about 1/4 inch apart. I used a different top piece to hold 1 27 watt white lamp for focussing. I picked a negative that prints on about a #2 grade enlarging paper to try. As soon as I projected the image onto the easel I saw my biggest problem-the light is VERY uneven. It is nice and bright directly under the bulb, but 1/2 inch away from the bulb the light is diminished by a good 2 stops. This is also true for the 4 BLB lamps- directly under them I had an exposure time of about 20 seconds at f/8 using a 135mm Nikkor with a 4x5 negative enlarged to 8x10, but a little bit away from the them the prints were very light. Also, the spiral pattern of the bulbs is visible as more uneveness. On the plus side I did not notice any focus shift going from white to UV light. I think if the uneveness problem can be worked out, this could be a useable system. Any suggestions, or questions? I will also post this to Michael and Paula's Azo site where I think the discussion really belongs.

    Richard

  8. #28

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    Quote Originally Posted by disfromage
    I had a chance today to make a prototype BLB head for my Durst 138 and it does show that the concept works, but their are some significant problems to solve. I used the bottom of the Durst condensor head as a pattern and cut a 1/4 inch thick piece of aluminum to replace the head. I then made a plywood box to fit over the negative carrier and suspended 4 BLB lamps from a plywood top. The bottoms of the lamps are about 2 inches above the negative carrier and they are quite close together, maybe about 1/4 inch apart. I used a different top piece to hold 1 27 watt white lamp for focussing. I picked a negative that prints on about a #2 grade enlarging paper to try. As soon as I projected the image onto the easel I saw my biggest problem-the light is VERY uneven. It is nice and bright directly under the bulb, but 1/2 inch away from the bulb the light is diminished by a good 2 stops. This is also true for the 4 BLB lamps- directly under them I had an exposure time of about 20 seconds at f/8 using a 135mm Nikkor with a 4x5 negative enlarged to 8x10, but a little bit away from the them the prints were very light. Also, the spiral pattern of the bulbs is visible as more uneveness. On the plus side I did not notice any focus shift going from white to UV light. I think if the uneveness problem can be worked out, this could be a useable system. Any suggestions, or questions? I will also post this to Michael and Paula's Azo site where I think the discussion really belongs.

    Richard
    This has been my concern when others suggested using multiples of lamps. I think that if one uses four lamps that exhibit the characteristics that you mention that a diffusion stage must be built. The easiest way to do this is to not have the bulbs themselves emitting directly onto the negative stage. I would plan on building a stryofoam enclosure in which the bulbs would enter from the sides and have stryofoam reflective baffles beneath the bulbs shielding them from the negative stage. These baffles would reflect the light emission upwards toward the top of the diffusion stage and this light from the top would then be reflected downward to the negative. This diffusion stage would have to be built oversize to provide for a top that was of the size needed to cover the negative holder. The angles of the baffles and dimensions would need to be worked out...the design should be fairly straightforward since the angle of reflection equals the angle of incidence.

    I still prefer the idea of placing a 400 watt HID Mercury Vapor lamp in the orientation of the original bulb and shuttering the lens. This seems like a much more straightforward approach since one is not totally reinventing the wheel.

  9. #29

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    Have you tried a diffuser? Try using a thin sheet of styrofoam for proof of concept. This will diiffuse he lights m, and therefore the highlights. The other idea is to place the bulbs FARTHER away from the negative, using the diffuser as well. Last idea.,.. a second diffuser. Double diffused light gets to be pretty even.

    To get more efficiency from the bulbs and to diffuse further, glue mirrors to all the walls of the light box head. You will; end up with what looks like a totally mirror interior. All surfaces get covered in mirrors. This will multiply the light source, and provide even further light evenness.

    Each of these ideas has a downside. Mostly loss of light. However, we can work on that after wwe find that there is a solution around the corner..



    On the subject of the Mercury bulb.. How do you propose to vent the heat from the bulb? Fan? Or does a Mercury bulb run cool?
    Frank Filippone

  10. #30

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    Have you considered for the L138S lining your box with highly reflectively Milar or mirrors and pointing the lights upwards and creating a very bright integration box? One idea may be to point a lamp at each intersection of the top and two adjacent sides.

    In general, if using tungsten lamps for print on AZO speed materials my biggest concern would be to use an exhaust fan to eliminate excessive heat. Such exhaust fans are available for the Durst equipment.

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