beseler diffusion head

chicagojoan · Feb 12, 2009

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.

David Brown · Feb 12, 2009

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?

John Koehrer · Feb 12, 2009

Same lens?

chicagojoan · Feb 12, 2009

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.

Nicholas Lindan · Feb 12, 2009

chicagojoan said:
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.

chicagojoan said:
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.

chicagojoan · Feb 13, 2009

Nicholas Lindan said:
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.

JRJacobs · Feb 13, 2009

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.

df cardwell · Feb 13, 2009

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/product/4551-REG/Beseler_857071_Universal_45_Lightsource.html

Nicholas Lindan · Feb 13, 2009

chicagojoan said:
<<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.

David Brown · Feb 13, 2009

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.

df cardwell · Feb 13, 2009

Looks complete, there wouldn't be a filter for the viewing (white) light, would there ?

It's cool.

Chan Tran · Feb 13, 2009

The univeral 45 uses 2 lamps and I believe they have fixed filter (I think it must dichroic too) and control the intensity of each lamp to get the color rather than moving the filters like the dichro 45S or the dichro 45 computerized color head. But all three have the same styrofoam core diffusion chamber.

David Brown · Feb 13, 2009

Chan Tran said:
The univeral 45 uses 2 lamps and I believe they have fixed filter (I think it must dichroic too) and control the intensity of each lamp to get the color rather than moving the filters like the dichro 45S or the dichro 45 computerized color head.

Not to nitpick, but I fear that Joan is probably confused enough, and this is not totally accurate.

Let me quote from the manual for this device:

"The Universal 45 system is a solid state, microprocessor controlled dichroic colorhead ...:

"Lamp: Cat No 81082V, 250W 3 required."
"Filtration: Red, blue, green."
"Type of Filtration: Dichroic interference filters."

There are three bulbs and filters. This is the configuration for the color controller. However, if one installs the vc controller, then the red is replaced with a clear one. But, you are correct that the filters don't move. It is the intensity of the lights that are controlled.

df cardwell · Feb 13, 2009

David

Start scanning that manual !

JRJacobs · Feb 13, 2009

Crazy - never seen or heard of one of these things. Learn something new everyday!

David Brown · Feb 13, 2009

df cardwell said:
David

Start scanning that manual !

Sorry. I paid actual money for it.

chicagojoan · Feb 14, 2009

controller pad

df cardwell said:
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/product/4551-REG/Beseler_857071_Universal_45_Lightsource.html

Thanks for the info and the link. It seems I do have the controller pad. See photo. I just need to find out how to use it.

chicagojoan · Feb 14, 2009

manual

David Brown said:
Sorry. I paid actual money for it.

So where did you get the manual?

David Brown · Feb 14, 2009

chicagojoan said:
So where did you get the manual?

http://www.khbphotografix.com/

You have the variable contrast (B&W) controller, btw. It's not hard to use, it serves as a timer and a way to set the filtration. Try printing with the controller set to grade 3 instead of using your other filters.

Chan Tran · Feb 14, 2009

chicagojoan said:
So where did you get the manual?

I actually paid money for several of the Beseler manuals that I need. I would be glad to scan them and distribute. There is nothing wrong with it because the manuals that I bought are also reproduction and not originals from Beseler. So someone had already violate copyright rule when they scanned and sold them to me.

jeroldharter · Feb 14, 2009

You have a very nice enlarger. The VC controller is not as common as the color controller. As noted, this is a dichroic head with three lamps and three filters. What is different than the standard dichroic head (the Beseler 45S) is that yours is additive and uses Red, Green, Blue filters instead of subtractive using Yellow, Magenta, Cyan filters.

I have never used your head. I bought a dead Universal head, have a color controller, but no power source. But if you set it for grade 5 I assume that the light output should be blue and grade 1 should be green if you want to verify that the controller is right. You should not have any trouble printing at high contrast.

The controller has an integral timer and I believe other functions such as print counters. I did not realize that the filters did not move but it makes sense if you look inside. I also did not realize that the red filter was swapped out for clear in the VC model. I thought you could just swap out the controllers.

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