Making my own condenser for Durst M700

[agenkin]

I have spent the last year waiting for the MF (Unicon 85 or Unicon 105) condenser for my Durst M700 to show up on eBay, and I'm thinking that I need to do something about it, instead of waiting. I'm thinking of getting my hands on a condenser lens from some other MF enlarger, and adapting it to my M700 by making a custom box to fit it into the head. I only want to be able to print 6x6 for now.

Is this a bad idea? Do I need to worry about distances to the mirror or to the negative? Has anyone done this?

I'd appreciate any input at all. Thanks!

 

[dario]

Hi Agenkin - You might be able to answer a question I have. I too have an M700. It has a Unicon 85 condenser, which is only good for 6x6, whereas the neg carrier is 6x9. Is the Unicon 105 suitable for 6x9? Thanks.

 

[agenkin]

I too have an M700. It has a Unicon 85 condenser, which is only good for 6x6, whereas the neg carrier is 6x9. Is the Unicon 105 suitable for 6x9?

Yes, as far as I understand, the number on the condenser corresponds to the diagonal of the negative (50 for 35mm, 85 for 6x6, 105 for 6x9). Note that this knowledge is purely theoretical - I haven't used my M700 for MF printing yet. But the enlarger is capable of handing up to 6x9 negatives, and the Unicon 105 is the biggest condenser for it. Hope this helps.

p.s. Would you like to sell your Unicon 85 condenser?

 

[dario]

Hi Arcady - Thanks for the info. No, I don't want to see my Unicon 85, but I'm interested to buy a Unicon 105, although my 105mm lens seems to work OK with my Unicon 85. However, I do wonder if I should be raising the condenser so that its distance from the lens is closer to the lens's focal length. I don't suppose you have a manual?

 

[agenkin]

However, I do wonder if I should be raising the condenser so that its distance from the lens is closer to the lens's focal length. I don't suppose you have a manual?

I have a hardcopy manual for the M700, which is pretty slim, and not very informative. I can scan it for you, if you want.

Why do you want to raise the condenser? Do you mean the distance from the condenser lens, or from the enlarging lens?

 

[dario]

Now you've made me think. I'm clearly a bit confused. The condenser should be a certain distance from the light source - right? That's why some enlargers allow you to raise and lower the bulb. In the M700, the position of the bulb is fixed, so shouldn't you change the position of the condenser for different condenser focal lengths? Does the manual say anything about that? I'd appreciate a copy, but don't want to put you to the trouble if it's not very informative.

 

[agenkin]

No-no, it's *me* who is confused. My question was that of ignorance, not that of instruction to think harder. I don't quite understand how condensers work, which, I thought, should be evident from my original post. You may be quite right about rising the condenser. I wonder if I can use the Unicon 50 for printing off 6x6 in the same fashion.

 

[dario]

There are two aspects (at least). One is the size (diameter) of the condenser. I've never seen a Unicon 50, but I suspect it won't be big enough for 6x6. The diameter of the condenser has to be at least as large as the neg diagonal. The other aspect is the positioning of the condenser with respect to the light source and the enlarging lens, and I'm not sure how critical that is - hence my question about raising the condenser. Hope that helps.

 

[dario]

Incidently, I've been looking at your photos - really interesting. Are you in Brazil?

 

[agenkin]

Thanks, dario, I live in Toronto, Canada. I visited Brazil for about nine days in August, and it fascinated me as a very photogenic country (and I only saw a tiny part of it).

I'll try to find some reading on how condensers work. I think that I can get a Durst M600 head with an 85mm condenser reasonably cheaply, but I don't know whether the distances there are comparable to distances in the M700. From what I've seen so far, the design is very similar.

 

[dario]

Good luck with the condenser!

 

[Ian Grant]

Some years ago there was a magazine article on making replacement Durst condensers, it wasn't difficult. They are easy to buy circular, its a case of trimming off the corners and making the holders.

I'm sure if you searched the web you could find how to form the glass into shape.

Ian

 

[Murray@uptowngallery]

I think Richard Ide (here, OM him) may understand the optics well enough to comment on any issues in adaptation (I'm not suggesting he'd give you step-by-step instructions, just that he has done some custom enlarger optics work for himself and probably has a good understanding of twhat one can get away with and what one cannot).

Oops, maybe PM would work better.

 

[agenkin]

Thanks, all. I spent some time searching the web, but found nothing. I'll try PM-ing Richard. Will report if I find anything useful.

 

[richard ide]

RE condensers

Hi Arcady,
For the purpose of this exercise let us assume the light source is a bare filament bulb (point source) rather than diffuse and for determining spacing by trial and error, I think it must be. The condenser should focus the light at some point within the enlarging lens. That determines the condenser/lens distance. I think you should focus a negative on the easel to arrive at the correct lens film distance. Remove the negative. IIRC a simple magnifying glass held in front of the enlarger lens will give an image of the filament on the easel. If the filament image is not sharp and fill the image circle, you need to change the lamp condenser distance. When using a point source for enlarging, the lamp condenser distance varies with each change in magnification for best results. A diffuse source is far less critical as far as lamp position is concerned.

I now need to take my foot out of my mouth and have a beer.
I hope this provides enough information.

Regards

 

[Christopher Nisperos]

I'm a M700 user, too. Here's a hint for future searches: shop the e-auctions on their various international versions. The different sites don't always seem to be hooked together. For example (and not to rub salt into the wound!),
you just missed a condenser 1-1/2 months ago . . .

http://cgi.ebay.at/Kondensor-DURST-...5404512QQihZ001QQcategoryZ15424QQcmdZViewItem

and another one, last month . . .

http://cgi.ebay.it/DURST-UNICON-105...2453997QQihZ018QQcategoryZ43479QQcmdZViewItem

and yet another, just two days ago ...

http://cgi.ebay.at/DURST-UNICON-105...8757727QQihZ013QQcategoryZ80377QQcmdZViewItem

I trust this will be helpful to you, in case your DIY project doesn't work out!

In my own case, I need 6x4.5, 6x6, 6x7 and 6x9 masks for my negative carrier! Has anybody out there got one —or several— of these to sell to a Durst-brother (me!) for a reasonable price? If so, please PM me .

Thanks and Happy New Year to y'all,

Christopher

.

 

[stefan4u]

First off all this shall be no misapplication of this great forum !

Some time ago I switched over to a Durst M805, the M700 is retired now. It's equipped with two condensors (Unicon 105 and Unicon 85) three diffuse mixing boxes (Setobox) for 35mm, 6x6m and 6x9 cm.
Ages ago I made one working unit out of two fragments, so some Parts are double, some single...

Double parts are the compete Enlarger head with lamphouse, lamphouse cover and mirror as well as the two light-tight bellows. There are two interchangeable dicroitic color heads (CLS70) but only one transformer. Anyway every 12V transformer who gives 100 watt power output will be useful instead. This will be a good option to use multigrade paper in conjunction with the mixing boxes.
There are two columms (the "tube side by side" one's, not the improved M800's one!) but only one basebord and one Setoneg (glassed) negative carrier. There is a pair of glassless negative mask for halfframe (Aumet 18) which can be rasped / grinded to convert it (to a Aumet 35) for 35mm negatives easily.

Because I know how hard these items are to get, I strived against a selling till now. Last not least it makes quite an ammount of work to wrap and ship all this.

If there is really interest for the entire unit or for the (majority of the) parts I could think it over, providing a fair salary. Give me a email stefan4u@freenet.de , maybe I can overcome my lazyness and start a ebay auction next weekend for each other's benefit.

One more point to think over, I'm located in Germany, so shipping costs may be higher than in the US...

Regards from Germany,
Stefan