Durst M605: can't focus 50mm Rogonar lens with bigger magnification -

[BobUK]

Wind the enlarger head up to maximum height.

Close the bellows up to their shortest.

Pop a negative in the carrier.

Remove the mounting flange completely from the lens.

Switch on the enlarger light.

Open the aperture to maximum.

Now carefully, by hand, hold the lens in the light path moving it up and down inside the bellows to see if you can get it to focus.

A bit fiddly, but it can be carried out enough to see a flash of focussed negative on the base board.




That should prove the problem to either the lens itself or the lens to negative distance problem.

 

[Ian Grant]

It's really an unfortunate combination of lens board, lens and desired magnification, nothing else.

And maybe deliberate design by Rodenstock, who wanted you to upgrade for larger prints. By the time the lens was made and marketed Durst were by far the largest enlarger manufacturer in Europe, followed by Meopta.

Ian

 

[koraks]

@Ian Grant as I was cooking dinner, the same thing occurred to me. It's possible Rodenstock really did deliberately limit its use.

@BobUK that's a good test and worth a try. I'm confident it will prove the lens as such focuses just fine; it's just a matter of finding a way to mount it high enough into the enlarger.

 

[BeselerOrNot]

Do you have some friend with Magnifax or Opemus

You guys have friends? Sadly, no.

 

[BeselerOrNot]

Now carefully, by hand, hold the lens in the light path moving it up and down inside the bellows to see if you can get it to focus.

Surely that was the first thing I did, and I see a focused image. But that still leaves the possibility that I assembled smth wrong, or some part is missing.
Looks like no, however.

 

[ic-racer]

Those of you that own the same enlarger, can you confirm the bellows is fully collapsed in the picture from the first post.

I have two enlargers that look similar (Minolta and Philips) in which the bellows collapses until the lensboard physically touches the negative stage.

 

[BobUK]

https://www.rodenstock-photo.com/sites/default/files/2020-04/e_Rodenstock_Printing_CCD_43-62__8230%20%281%29.pdf

I have just tried my M605 with the Durst 50mm lens.
Set at 8x magnification it projects an in focus image of 28 cm x 18 cm. Roughly two centimetres smaller on each dimension than A4 paper size. I think you mentioned A4 paper size as your maximum.

Looking at the Rodenstock website for enlarging lenses, see the link above, scroll down and read the full specification.
It looks like 8x is the maximum enlargement.
Have a good read and see if you think the same as me.

It,s a new one on me if that is the case.

 

[BobUK]

Those of you that own the same enlarger, can you confirm the bellows is fully collapsed in the picture from the first post.

I have two enlargers that look similar (Minolta and Philips) in which the bellows collapses until the lensboard physically touches the negative stage.

I, it looks fully compressed to me, but have a read of my previous post just now.

 

[pentaxuser]

The Rogonar is a typical Cooke triplet enlarging lens. It’s not terrible and can certainly make prints lager than the A4 cited.

This comment from post #2 succinctly states the real problem.

“Inability to focus due to insufficient focus travel/compressed bellows means that the lens is simply too far away from the negative.”

This is true for any lens, from the lowest price triplet, to an expensive apochromat.

There is no mystery. You need a different lens mount that places the lens close enough to focus.

It just seem strange that Durst fails to warn its user that the SIRIOTUB recessed lens holder does not work with the Rogonar that the OP has got.
At least in my manual which Durst calls the Operating Manual I can see nothing there, as I said before, that gives any warning that some lenses such as the Rogonar -S will not work with the standard SirioTub recessed holder

pentaxuser

 

[BeselerOrNot]

the bellows collapses until the lensboard physically touches the negative stage.

Wow, that's pretty cool. Nothing like that with Durst.

 

[BeselerOrNot]

such as the Rogonar -S will not work

Rogonar-S probably will. This is "just" Rogonar, and from the Rodenstock's paper they have a very different design.

 

[pentaxuser]

Cheaper enlarging lenses are likely optimised for 8 x 10 prints.

But optimised in what way? I can appreciate that print quality in cheaper lenses may suffer more beyond a certain magnification but that's quite different from not focusing beyond 8x10, surely? It's this lack of ability to focus up to A4 that is the sole issue here - at least from my understanding of the OP's problem

pentaxuser

 

[pentaxuser]

Rogonar-S probably will. This is "just" Rogonar, and from the Rodenstock's paper they have a very different design.

Sorry I got the name wrong but the essence of my post still stands doesn't i.e. I find it strange that Durst does not mention this lens as being unsuitable for any magnification beyond what I assume to be 8x10 on the basis that magnification to A4 is impossible

However if you are convinced that this is the case than that's fine. Best of luck with finding a suitable lens

pentaxuser

 

[BeselerOrNot]

I find it strange that Durst does not mention this lens as being unsuitable

The lens could be just newer than the enlarger itself

 

[ic-racer]

Wow, that's pretty cool. Nothing like that with Durst. View attachment 367581

This is what I meant by touching, the outer lip of top and bottom touch so the bellows is no longer visible.

 

[pentaxuser]

This is what I meant by touching, the outer lip of top and bottom touch so the bellows is no longer visible.

View attachment 367592

Yes you certainly can't do that with the Durst M605

pentaxuser

 

[Mark J]

Looking at the Rodenstock website for enlarging lenses, see the link above, scroll down and read the full specification.
It looks like 8x is the maximum enlargement.

I think Rodenstock there will be quoting an optical (optimum range) specification for the lens, they wouldn't quote a limit connected to any specific enlarger. That's the normal convention.

 

[ic-racer]

Brute force solution...

Seems someone else may have had a similar experience and they have made a 3d printed Siriotub replica with a 37mm recess.

Durst siriotub36 M39 Replica 3D print for M605 enlarger | eBay

Durst siriotub replica ut in depth 36mm instead of 17mm M39 threading 3D print in PLA.

www.ebay.com

 

[BeselerOrNot]

it's just a matter of finding a way to mount it high enough into the enlarger.

Yeah.. I even tried to reverse the lens, mounting it from inside the bellows. This kinda worked, in terms of focus, but the aberrations were wild -- distortion, field curvature and overal lack of any sharpness outside the center. Not to mention the unaccessible aperture ring

 

[BeselerOrNot]

Seems someone else may have had a similar experience and they have made a 3d printed Siriotub replica with a 37mm recess.

One sold! so there were at least two unfortunate guys

But looking at the Durst Neonon for just 10 dollars more, I think it's a better option.

 

[MattKing]

Brute force solution...

Seems someone else may have had a similar experience and they have made a 3d printed Siriotub replica with a 37mm recess.

Durst siriotub36 M39 Replica 3D print for M605 enlarger | eBay

Durst siriotub replica ut in depth 36mm instead of 17mm M39 threading 3D print in PLA.

www.ebay.com

Most likely this is the sort of solution you need for that model of lens.

The lens could be just newer than the enlarger itself

Correct. Or the lens may be a model that was not readily available in the markets where the M605 and that version of the Siriotub were common.
Durst availability varied widely around the world - at least with respect to the amateur market. For example, they were widely available in Canada, but relatively hard to find in the USA.

I repeat my earlier observation - not all 50mm lenses work with all mounting systems for all enlargers.

 

[BeselerOrNot]

The Rogonar is a typical Cooke triplet enlarging lens.

That's interesting, because I thought f/2.8 is only achievable in Triplets when using a high-refractive index materials (regular glass gives f/3.5). I doubt that Rogonar enjoys Lanthanum, so.. plastic?

 

[Mark J]

In the 80's/90's era (at least), the Rogonar was a triplet, the Rogonar-S was a Tessar ( 4-element ) and the Rodagons are 6-element.
Tessars are OK at f/2.8 with high-index glass. However, there was a Roganor triplet at f/3.5 and one at f/2.8.
They would need high-index glass for that aperture, and the performance graphs of the f/2.8 version show that it is still a 'stretch' for a triplet

Really, these days with the 2nd-hand market, there are so many great 6-element lenses available from Schneider, Rodenstock, Nikon and Durst, that if you can afford an extra £20, then just do it.

 

[BeselerOrNot]

Durst, that if you can afford an extra £20, then just do it.

Already did. Waiting for Royal Mail to do it's part. I hope that Durst Neonon won't have the same issue!

 

[Melvin J Bramley]

But optimised in what way? I can appreciate that print quality in cheaper lenses may suffer more beyond a certain magnification but that's quite different from not focusing beyond 8x10, surely? It's this lack of ability to focus up to A4 that is the sole issue here - at least from my understanding of the OP's problem

pentaxuser

I'm no optics expert!
perhaps the cheaper 50mm lenses are optimised for lower magnifications.
I have two 'wide angle" enlarging lenses.
A 40mm Nikon for 35mm negs and a 60mm Tominon for 6x6 negs!
With that in mind the Nikon 80mm, not the usual 90mm suggested, is said to cover 6 x 7.
It is confusing but i think the original poster has either an assembly issue with his m605 or should just purchase a better lens that is readily available inexpensively.