Hello,

I'm returning to my darkroom after a regrettably long absence. I've hit a frustrating problem I wondered if anyone here could shed some light on (so to speak...).

I have an Agfa C66 which is a re-branded Durst M605, I have two enlarging lenses an 80mm and a 50mm. I've only ever used the 80mm lens which has been fine for my medium format work and the occasional small 35mm enlargement.

I'm now wanting to do more 35mm work. Using the 80mm lens for this means that for a 10x8 enlargement I have to have the enlarger head almost at the top of the column giving unacceptably long exposure times.

I decided to give the 50mm lens a go, but I can't seem to make enlargements bigger than about 13x18cm (5x7"). At this size the focusing stage is up as far as it will go and the bellows is completely compressed making it impossible to focus the image if I try to go any larger.

I'm obviously missing something fundamental here. I know I should be able to enlarge to well over this size with a 50mm lens so I must be doing something wrong. Does anyone have an idea of what that might be?

Many Thanks,

Ben.

Not sure about this specific enlarger (I have a M70) but if you have a "tube formed" lensboard (Vegatub 39?) you can try reversing this one to get the lens closer to the negative. If that doesn't work you will probably have to get another lensboard made for the 50mm (maybe Sinopla 39).

Regards,
Thor Egil

Thanks for your suggestion, I did wonder about the lensboard.

My enlarger came with two Siriopla lensboards, both identical, I had assumed they could be used with both lenses. I read that the Siriopla 39 is recommended for 50-90mm lenses, so I thought what I have should be OK.

It seems odd that the 'correct' position for the 50mm lens would seem to be about half way up the bellows when they're fully compressed. This would require a heavily recessed lensboard, perhaps such a thing exists and that's what I'm missing?

Perhaps the whole focusing stage & bellows are interchangeable and I have the wrong kind?

It's not unusual to use a recessed lens board with a 50mm lens to overcome the problem you describe.

The M601 I used to use a lot had a "Setopla 2838" recessed plate for the 50mm lens. Without it, as you found, only small prints could be made.

It's the same plate used for some of the more modern enlargers like the Laborator 1200, so there may be some stocks available new. Jobo USA have them on their website:

http://www.jobousadarkroom.com/products/durst_l1200.htm

(scroll down for the accessories)

I've got an M70, and I have to use a recessed lensboard for my 50mm.
I believe it's called a siriotub or something similar.

It's not unusual to use a recessed lens board with a 50mm lens to overcome the problem you describe.

Yes, my LPL uses a reversible lens mount - one way it's recessed for 50mm, turn it over and it projects for 80mm. I don't know the Durst but might it be that simple?

Yes, my LPL uses a reversible lens mount - one way it's recessed for 50mm, turn it over and it projects for 80mm. I don't know the Durst but might it be that simple?

You can't reverse the Durst boards. I tried it once, but it leaked light everywhere.
They have a stepped side and a chamfered side - the chamfer must face down

I've just checked my manual, and the correct board for the 50mm is the Siriotub 39. As I said before, I have an M70, but I think the boards are interchangeable.

I can tell you where to get the Seriopla, if you have a time finding stuff for the M605. I got mine from Barry Newhart, who does M605 repairs. He also answers questions happily. Nice guy! 610 525-69998.

I have a Lapla 39, which is more flat, for the 80mm lens and the more cup-shaped Seriopla for the 50.

Also, like I pm'd... if you ever still have problems focusing after changing lenses, sort of move that head forward a tad and back again into position - then try focusing. I often have to do that. Don't know why.

Janet

Thanks all for your help and advice.

It seems I'm using the wrong lensboard, my two Siriopla lensboards are for use with the 80mm lens and I do indeed need a recessed board for the 50mm.

I've just found and ordered a Siriotub 39 lensboard (which is cup-shaped) so I'll give that a go.

Thanks again,

Ben.

The lensboard issue is almost certainly correct; however, for the benefit of other readers who might search for and find this thread in the future, I'll mention that there are 50mm lenses, mostly made in Russia, that have longer barrels than most. These lenses don't work well with many Japanese and Western enlargers, at least not for prints over a certain size. For instance, I've got a Russian Vega-11U 50mm lens which works well for up to about 11x14-inch enlargements on my Philips PCS130, but beyond that it's impossible to focus. On a Durst C35 I used to have, such lenses won't work at all for anything bigger than about 4x6 or 5x7-inch. Russian enlargers obviously were designed to put the lens threads closer to the negative than most enlargers people here would use. A few such lenses use a removable extension tube, and so can be easily "fixed" to work well. I've got an Industar-50U which is built like this; to use it with a Western enlarger, the extension tube can be removed and it'll work fine. Sadly, the higher-quality Vega isn't built this way.

A big added benefit with my 50 is that max fstop is 2.8 whereas its 5.6 for the 80. The extra light with the 50 is a big help in focusing.

If yours is the Durst M605 by any other name don't forget the switch to the 35 box instead of the 66, otherwise the light level suffers a little.

pentaxuser

Thanks to the remarkably quick service from an eBay seller I can confirm that the lensboard was the issue.

My new Siriotub recessed lensboard works a treat with my 50mm lens. I'm very pleased to have this problem resolved so I can get on with some printing this evening. Thank you to everyone who pointed me to the problem!

The lensboard issue is almost certainly correct; however, for the benefit of other readers who might search for and find this thread in the future, I'll mention that there are 50mm lenses, mostly made in Russia, that have longer barrels than most. These lenses don't work well with many Japanese and Western enlargers, at least not for prints over a certain size.
...


Out of interest I tried a (rather poor quality) 50mm lens I have from an ancient Russian enlarger and have found the same thing. This lens has a long barrel and so doesn't work for anything other than small enlargements, even with the recessed lensboard.

Ben.