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  1. #1

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    beseler diffusion head

    Is low contrast a characteristic of diffusion heads? Or am I doing something wrong? I'm printing for the first time with a diffusion head (Beseler universal 45), and finding that negatives that printed beautifully with a #3 Ilford filter (on Forte paper with a cold head) look dull and flat even with a #4 on the Beseler. I know, I know--I shoulda tried it with a 5. And I will.

  2. #2
    David Brown's Avatar
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    How are you setting the Beseler for "#4"?

    A dicroic head such as the Beseler should not be lower contrast than a true diffusion head. It might have slightly less contrast than a condenser head, though. What were you using before that printed well at grade 3?

  3. #3

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    Same lens?
    Heavily sedated for your protection.

  4. #4

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    Thanks to both of you. The Beseler Universal 45 isn't a dichroic enlarger--it has diffusion chambers lined with styrofoam. Apparently, it's a head that wasn't widely distributed (and it's no longer made). I'm using Ilford filters--the very same set of filters I was using on a cold head enlarger in a college darkroom (sorry I can't remember the name of the head). As to lenses, the Beseler is in my home darkroom, so I've had to revert to my own lens (a Nikkor). It's a lens that worked well with my old Saunders condenser enlarger.

  5. #5
    Nicholas Lindan's Avatar
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    Quote Originally Posted by chicagojoan View Post
    The Beseler Universal 45 isn't a dichroic enlarger--it has diffusion chambers lined with styrofoam.
    That is what a dichroic head is. Dichroic refers to the type of filters that are let down over the lamps that illuminate the diffusion chamber.

    It is a very common head.

    Quote Originally Posted by chicagojoan View Post
    I'm using Ilford filters--the very same set of filters I was using on a cold head enlarger in a college darkroom.
    The filters will behave differently with a cold light head. Unless you are using a special tube in the cold light head, or a heavy yellow filter, the results from a cold light head will be up to several grades higher in contrast.

    Both the cold-light and the Beseler Universal are diffusion light sources. There will be no contrast increase because of Callier effects, as can happen with condenser lamp housings.

    A common cause of lowered contrast is a dirty enlarging lens. When clean all modern enlarging lenses will deliver adequate contrast.

    If you are not getting enough contrast with a #4 filter, and the subject matter is normal, you may want to increase your film developing time.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  6. #6

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    [QUOTE=Nicholas Lindan;752165]That is what a dichroic head is. Dichroic refers to the type of filters that are let down over the lamps that illuminate the diffusion chamber.

    It is a very common head.

    I guess I don't understand what constitutes a dichroic enlarger. I thought an enlarger that required the use of external filters--in this case filters that fit in a carrier BELOW the lens--was, by definition, not dichroic. I thought a dichroic head had an internal system for separately subtracting each of three colors. When I said it wasn't a very common head, I didn't mean dichroic heads. I meant the Beseler Universal 45. The technical manager of a local college darkroom (for the past 25 years) had never seen one.

    I'm uploading photos of the head, in case they clarify something.
    Attached Thumbnails Attached Thumbnails diff_head.jpg   diffus_head_open.jpg  

  7. #7

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    Looks just like a Dichroic head, but without the dichro filters - otherwise it is the same as the dichro head on my Beseler 45.

    It shouldn't give you much difference than using a condenser head - definitely not to the dramatic level you describe - something else is wrong.

  8. #8
    df cardwell's Avatar
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    Joan

    This is a VERY special and fine gadget. Do you have the controller pad ?
    It is an additive head, and depending on the controller, is either a closed loop system
    for multigrade B&W or color printing. You have three lamps: a blue, a green, and a white.


    Maybe an APUG search will find some info ? It was a VERY expensive, and fine head. It WOULD be nice if you have the controller.

    Here is a link to the B&H data:
    http://www.bhphotovideo.com/c/produc...ghtsource.html

  9. #9
    Nicholas Lindan's Avatar
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    Quote Originally Posted by chicagojoan View Post
    <<pictures>>
    I stand/sit corrected ... it isn't a common head, I had a mental image of another one.

    It is a dichroic head, though: there are filter holders in front of the Red, Green and Blue bulbs (the ones with red, green and blue wires going to them). There should be dichroic filters in the holders but they seem to be missing. And there should be a controller that times the three lights separately, which if it is missing, explains the lack of filters.

    'Dichroic head' is more a generic term for such a head - it could have gelatin filters and it would still get called a 'dichroic head'. Gelatin filters would burn up in front of the halogen lamps and so dichroic filters - made from a thin layer of metal sputtered on to glass - are used instead.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  10. #10
    David Brown's Avatar
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    Do you have the controller? There are (were) two available controllers, this one pictured for color and another for "variable contrast" B&W. Of course, the color controller can be used for B&W. Without the controller, though, I don't know how the head even works.

    As with any dicroic head, the filters are built in - you do not use external filters with these types of heads.

    If you were using a cold light before, it could possibly have given you more contrast depending on the type of cold light it was. Many of them were designed for graded papers and the color of the lamp is very contrasty with VC papers.
    Attached Thumbnails Attached Thumbnails Uni45 controller.jpg  

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