Head absorbing glass for 23c II has NO EFFECT :-(

Discussion in 'Darkroom Developing and Printing' started by Phil Glaser, Aug 15, 2004.

  1. Phil Glaser

    Phil Glaser Guest

    Hi,

    I recently shelled out $20 on e-bay for a sheet of heat absorbing
    glass for my Beseler 23C II and am VERY disappointed to find that it
    does absolutely nothing to resolve my negative popping issue. My
    testing procedure is to leave the enlarger on for about 30 seconds and
    then focus with a grain focuser. I then shut off the enlarger, wait
    about 10 seconds, and observe whether the the negative is still in
    focus. I have tried taping both edges of the negative to the negative
    carrier (pulling tightly to create lots of tension) and now the heat
    absorbing glass, and the result is the same every time: the negative
    is no longer in focus, but pops back into focus after about 10-15
    seconds. (And I am _still_ taping _with_ the heat absorbing glass.)

    WHY WHY WHY??? Where did Beseler go wrong with this model? I paid $75
    for this enlarger. Am I now going to have to shell out $130 for an AN
    glass carrier to solve this problem (I cannot find one used anywhere).
    If I had known this was going to happen I would have bought a
    different enlarger.

    Is there really NOTHING else I can do to solve this problem?

    Thanks for hearing my rant.

    --Phil
     
    Phil Glaser, Aug 15, 2004
    #1
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  2. Pheeewww... So your head is still where it belongs. :)

    SCNR,
    Ralf
     
    Ralf R. Radermacher, Aug 15, 2004
    #2
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  3. What format are you using? What carrier?
     
    Michael Scarpitti, Aug 16, 2004
    #3
  4. Phil, your surname is close to describing what you should do to solve the
    problem. Get some picture framing glass and make your own glass
    carrier.The fancy metal frame of the 23C is nice but not necessary. Take
    two sheets of glass large enough to stick out of the slot for the carrier
    and mask them with black tape or construction paper for the size of your
    negatives. Put the sandwich in the slot, center it, and close the slot.
    This will work, but with added risk of dust particles.
     
    PATRICK GAINER, Aug 16, 2004
    #4
  5. This seems to be a very common problem when using glassless
    negative holders. I have the same problem with my Omega D2V. I have
    not tried heat absorbing glass but I am not sure it would cure the
    popping. I have glass type holders for all formats that I use but the
    are a PITA because of having four surfaces to keep clean in addition
    to the film. I find popping varies with the weather, probably with the
    humidity but very often have to resort ot warming up the negatives
    until the pop and become stable and then either turning off the lamp
    briefly until I get the paper in, or using a card as a rudementary
    shutter to control the exposure. What I do is to warm up the negative,
    compose and critically focus. Then I turn off the lamp, put in the
    paper and block the lens with a card. Then turn on the lamp for long
    enough to pop the negative, then I can either make the exosure with
    the card or turn off the lamp for a second, move the card out of the
    way, and start the exposure with the timer. The negatives don't seem
    to un-pop for a couple of seconds, long enough to do this. Glass
    holders really are the best for sharpness but have the dust problem
    plus the possibility of creating Newton's rings. Newton's rings are
    interference pattern caused by reflections between the glass and the
    negative surfaces. There are various ways of dealing with them,
    probably an anti-reflection coating on the glass would work best but I
    don't know if such exist. I don't think the enlarger is badly
    designed, all of them with simple lamphouses have similar problems.

    Richard Knoppow
    Los Angeles, CA, USA
     
    Richard Knoppow, Aug 16, 2004
    #5
  6. Phil Glaser

    Jim Phelps Guest

    Phil,

    You didn't say which head you're using on the 23C-II. I have the older
    Dual Dichro (with the external power supply) and it uses a 200W
    Quartz-Halogen bulb. I do not have negative popping problems and I do use a
    piece of crystal glass (so as not to get the green from normal plate glass)
    for heat absorption.

    Could you have a problem with heat dissipation? I mean, if you're using
    a Dichro color head and the vents are blocked, this could be a source of
    your troubles. If you're using the standard head (light bulb), did you up
    the wattage from the recommended 75 watts?

    FWIW, I moved the fan out of my head for a reduction in vibration. I
    used a bathroom fan, the kind that sit in a 4" standard round duct and
    connected the wall mounted fan to the head with a dryer hose. Works well.

    Anyway, check the air flow in the head to make sure it's not being
    obstructed. The heat from the bulb has a long way to travel and an awful
    lot of glass to heat before the heat gets to the negative stage. 30 seconds
    seems real quick to me.

    Jim P
     
    Jim Phelps, Aug 16, 2004
    #6
  7. Phil Glaser

    Phil Glaser Guest

    35mm. I'm using the vanilla 35mm carrier that came with the enlarger.
     
    Phil Glaser, Aug 16, 2004
    #7
  8. Phil Glaser

    jjs Guest

    I have done very large enlargements with the XL version of your enlarger.
    Negative movement was an issue, and to cope I would 'preheat' the negative,
    then turn off the enlarger and _immediately_ hit the timer botton (foot
    switch). That usually worked, but in the end I gave up and got a Focomat.
    Cheap. You might want to look into getting a glass carrier.
     
    jjs, Aug 16, 2004
    #8
  9. Phil Glaser

    Phil Glaser Guest

    Har! As always, the answer to suffering is to look within.
    I'm a little concerned about getting cut from the edges of the glass.
    If I fold skotch tape around the edges of the glass, that would create
    a slight gap between the sheets of glass that might not be a bad
    thing: would it not solve the newton ring problem ?

    On the other hand, I'm imagining some kind of plastic 3/4 square
    plastic strip that I could pop around the edges of both sheets to hold
    them together. Somewhere, for some purpose, there must be such a
    thing.

    And if I did end up w/Newton rings, I could just by a sheet of an
    glass (http://www.fpointinc.com/web_store/Products/focal/fpnewt2.htm).

    The dust problem is a fair trade for the negative popping issue.

    Thanks. I think you just saved me $100 bucks!
     
    Phil Glaser, Aug 16, 2004
    #9
  10. Phil Glaser

    Phil Glaser Guest

    I have the standard head.
    This is an intriguing suggestion. The letering are no longer visible
    on the bulb, but it looks just like the 75w bulb as for example in
    this illustration: http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=137121&is=REG.

    Is it possible to get a stronger bulb that would have the same shape?

    You may be on to something here. I am using the enlarger in a very,
    very small closet. There's just barely enough room for me and the
    enlarger, and I'm not a huge guy. (My wet space is in a bathroom and I
    use a print drum.) So perhaps, indeed, the volume of air in that
    closet is not sufficient to enable the head to dissipate the heat,
    even from the normal 75W bulb. Does that sound plausible?

    I never spend more than 10 minutes at a time in that closet to avoid
    asphyxiating myself, but I'm starting to think that I ought to have
    some kind of ventillation.

    --Phil
     
    Phil Glaser, Aug 16, 2004
    #10
  11. I've never known "heat absorbing" glass to have much of an effect; but
    then, I've never had much trouble with negative popping in the 23c. I'm
    going to assume you're using the condenser head - are you using the
    recommended bulb?

    Assuming everything is configured right, and you still need to solve
    the problem at minimal cost, you can certainly work with two sheets of
    glass. I've done it; you'll get lower contrast due to scatter unless
    you mask carefully with black tape, around the negative and edges of
    the glass.

    Newtons rings were explained in another post; gapping the glass as you
    mention would reduce the area but not eliminate them. Commercial glass
    carriers usually use "newlo" or anti-Newtons rings glass. This does NOT
    have an "anti reflection" coating; it has a very, very slight texture
    to the underside of the upper sheet of glass. It prevents a molecular
    contact between the glass and negative.

    Newlo glass used to be commonly available in sheets. I have no idea if
    it still is now.
     
    Scott Schuckert, Aug 16, 2004
    #11
  12. It is also possible to make a carrier with glass on the top only, masonite
    or mat board on the bottom, cut out of course to fit the negative. The
    buckling is convex upward and thus is at least minimized by the glass on
    top. This means only two surfaces to clean.

    When I have had problems with Newton rings, it has been because of a speck
    of something causing uneven contact with the glass, or a wet spot on the
    neg. Waviness in the glass can also be a culprit.
     
    PATRICK GAINER, Aug 16, 2004
    #12
  13. Phil Glaser

    jjs Guest

    Patrick, have you ever used an oil-immersion carrier?
     
    jjs, Aug 16, 2004
    #13
  14. Yes, enlargers with a right-angle lamphouse that employ a mirror to
    reflect the light but not so much of the heat are superior.
     
    Michael Scarpitti, Aug 16, 2004
    #14
  15. Phil Glaser

    f/256 Guest

    Take sandpaper and sand round the edges and corners of the glass.
     
    f/256, Aug 16, 2004
    #15
  16. Nope.
     
    PATRICK GAINER, Aug 17, 2004
    #16
  17. Phil Glaser

    Jim Phelps Guest

    Yes. It may be worth chucking the current bulb for one of known wattage.
    By all means, get some type of ventilation into that closet. Don't forget,
    you need a fresh air inlet as well as some form of outlet. That outlet can
    be a simple as a stack to the attic. Remember heat rises, so if you have
    the ability to place a duct or vent in the ceiling of the closet into an
    attic (which should be almost dark, but if not you can baffle the duct to
    make it light tight) this would do. Place the fresh air intake low to the
    floor. This way, it's not unsightly when you need it as a closet again and
    there isn't any wiring to fool around with.

    Hope I've been helpful.

    Jim
     
    Jim Phelps, Aug 17, 2004
    #17
  18. Phil Glaser

    Mike King Guest

    To expand on the above get the stuff the body shop uses to sand body
    repairs. Called wet or dry (3M makes one) its black in color and tough
    enough to sand glass.
     
    Mike King, Aug 17, 2004
    #18
  19. Phil Glaser

    Mike King Guest

    The standard 75 watt bulb "211", the 150 watt "212", and the discontinued
    "213" (250 watt) all have the same size, shape and form factor (as do some
    photoflood lamps) so you could be using too much lamp.
     
    Mike King, Aug 17, 2004
    #19
  20. Phil Glaser

    Phil Glaser Guest

    Yikes! That does it then. Step one, get 75 watt bulb; Next
    contingency, home-brew glass negative carrier with vanilla glass; Next
    Contingency, anti-newton glass.

    Thanks. This all has been really helpful.

    --Phil
     
    Phil Glaser, Aug 17, 2004
    #20
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