View Full Version : Modifying the Beseler CB-7

9-Mar-2008, 10:01
I have a Beseler CB-7, and everything is great on it.

However I was wondering about modifying it. The big reason is the head is only B&W, so I wanted to upgrade the head to a colour filter one - that way I can use multigrade paper more effectively.

The recent FS ad for the £350 Kamm 8x10 had me thinking though.

I don't want a massive enlargement - I don't have the means or the budget to produce prints larger than maybe a step or two above 12x16. For 4x5 there's a Devere 504 at college on a huge column.

The Beseler stands at about 6ft, which is great. It's a little shy of the shed's ceiling.

I can't fit a 8x10 column, since they run about twice as high.

Think it's possible to modify the Beseler CB-7 to take a 8x10 head and bellows, using the motorized base?

That way I can use my half-plate and even the 8x10 camera sat on the shelf and enlarge to modest sizes. I could have a multigrade/colour head on there too - full control of tones and up to 8x10 enlargement :)

Any help on that would be great, I'll have a look later at how difficult it would be to hack at the CB-7, but if it's not going to work then I'll forget it.


9-Mar-2008, 10:29
Hmm Beseler sells or used to sell an 8x10 kit for their 4x5 enlargers. The CB-7 might need the no longer available adapter to fit the heads from the other smaller Beseler 4x5s. But when I mounted a colour head to my CB-7 I think I used cardboard for an adapter -)

You should do the math but I don't think you'd need to modify the bellows for a 240mm lens like Besler used to sell.

Basically you need an open ended box that would sit in the place of your current head. The new head sits on top of that. The box gives you the added distance. The negative holder. It's also sort of V shaped. If that makes sense. I guess about 7x7" at the bottom but larger in the top.

A few sites used to exist on converting enlargers to 8x10 but I haven't looked in a few months. Do a google search. I remember one with good pictures.

Other then that work with the formulas. The CB-7 is a good starting point and shouldn't need any hacking.

The problem is what are you going to use for a light source? Arista seems to be very slow in producing heads and I've no idea if you can even get one in Europe.

9-Mar-2008, 10:46

Clive is selling the "Super Chromega F Dichroic II head" with the enlarger. I'm wondering if that will work.

As you are saying, I hoped that I could lift all the original head off, attach a spacer of some sort, then place the new head on top. I'm worried about stability though. We'll see.

I think if I put more consideration in, I'm more likely to do 5x7 than 8x10, so I'm more likely to source a 5x7 head with a smaller spacer/box. I'm not sure if 8x10 will be overkill considering my space constraints.

Then again, if a 8x10 head is cheaper and more available than a 5x7, I'd get that after all.

9-Mar-2008, 10:55
How much will I be paying for a 5x7 colour head do you think?

9-Mar-2008, 10:58
I'd say at least 10x10 so you can turn the negative.

Play with the formulas if the biggest you want is say 24x30 [3x] I bet you'll find that the bellows etc won't need changing. It's just the box. Stability depends on the weight of the head but the CB-7 is almost 200lbs itself so it's not exactly your average waif.

9-Mar-2008, 11:02
I guess the speed I'd need to find £350 AND a lift to Bristol and back might mean I miss this. It's a few weeks before I get paid, the other half won't be pleased, nor will my family I'm still living with!

Thanks though Nick, at least I know it's possible. Maybe by the time I can do it, there'll be another deal to be had.

10-Mar-2008, 03:44

I'm buying the 8x10 enlarger. If anybody could pass me onto resources on the adapter kit for Beselers I'd be really appreciative :)