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Doremus Scudder
13-Jun-2017, 15:36
I have a couple of Chromega II dichroic heads in excellent condition that I would like to mount on my Beseler 45M-series enlargers. One is a Super Chromega II D (4x5) head and the other is a Super Chromega II E (5x7) head. Ideally, I'd like to adapt the 5x7 head to the 45M to give me as much illumination area as possible.

I've seen adapter plates for other systems, and I can make one similar without much difficulty. However, I have also seen a photo of a 45M with a Chromega II D head that simply sat right on top of the negative carrier, like they do on the original Omega enlargers.

So, I'm wondering which approach is best, 1) make an adapter plate and mount the head to the top of the condenser stage (upper bellows) or 2) somehow remove the upper bellows and figure out a way to mount the head to the crossbar to which the condenser stage is currently mounted (hope that makes sense).

I'd love to hear from anyone who has used/adapted the Beseler 45M to take the Chromega head. Any pointers, tips, experience, etc., would be greatly appreciated.

Best,

Doremus

LabRat
15-Jun-2017, 01:15
Hi!!!
I have done several Beseler conversions for cold lights, color heads etc, and know the Chromega heads, so I will explain the challenges here...

First, the Chromega heads are designed to work with the lift arms, and press their rubber gasket to the top of the neg carrier, which is about a half inch from the diffuser to neg... The Beseler color head sits on the top shelf of the head, and the mixing chamber/diffuser is in a cylinder that goes down just above the carrier, past the upper bellows/stage... The big problem is that for corner to corner illumination (for 4X5), the diffuser has to be around 1/2" or less from the neg, or you get that "tunnel effect" that clips the corners... So the Beseler (that was designed first to be used with the condensers) is a little hamstrung when adding any aftermarket head (like a cold light) or conversion... (Even some of the later Beseler made heads will barely cover the corners with 4x5...)

So the list of options are;

#1/ Get a small 6X6 color head (like an Omega B), make a tube (out of ABS/PVC drain pipe, metal, large can of beans, etc) to replace the lamphouse, and put the head diffuser at the same height where the lamp was, and use the condensers... (This will give you the edge sharpness of a condenser, and color mixing... If you ever print color, this gives the color saturation AND edge sharpness!!!)

#2/ Find the Beseler color heads, but they are often missing an internal diffuser etc, or some had those stupid controller boxes needed to just turn the filters (no dials), had fussy electronics, and still could clip corners... (I have one with the dials, and very complicated 2 lamp system (dual 300W lamps, heavy fan box, vac cleaner hose, 40lb voltage regulator, etc, that I still didn't get to figuring out yet, but what a beast!!!

#3/ You might be able to machine a new top shelf for the Chromega to mount to the top of the monorail, but it must be strong enough to hold the head without sagging (this becomes an alignment plane/maybe 5/16" or possibly 3/8" alum plate???) and allows the diffuser to be much less than a half inch from the neg, the upper bellows and lever operated neg holder stage shelf are gone, the knob operated top neg stage is installed upside down, and has the lower bellows remounted to it (this stage then pushes up the neg carrier UP to the top shelf to close)...

Done right, this can also allow a 45 to have EXCEPTIONAL alignment... (I did this to a 45 with an Aristo cold light head, and my machine measuring tools tell me it is holding better than a .0002" alignment!!! I'd post pix, but my enlarger just went into storage as I'm moving right now...)

But I think adding a small color head is probably the best bet, cheap ($20-$40) and use the condensers... Get an old Polaroid MP4 and figure out a way to mount one of those Chromegas on it with a sliding neg carrier... ;-)

Good luck, and happy thinking!!!

Steve K

Doremus Scudder
16-Jun-2017, 10:07
Steve,

Thanks for the detailed reply. Thanks for confirming that the diffuser needs to be close to the negative. I think I have a viable approach now.

Frankly, I'm surprised that I got so few responses here and over at APUG (zero there so far...). I figured this had been done often before. Maybe that's not the case. At any rate, I'll document my conversion and post it here when all the bugs are worked out.

Best,

Doremus

ic-racer
16-Jun-2017, 14:13
Seems easier to me to just look for an Omega chassis. In the USA they are pretty common. The 4x5 head would fit on a d2, d3, d4, d5, d6, ProLab, D5500 etc.