Heliar 21cm Lens Won't Focus: Elements in Wrong?

[aeyb701]

Greetings all:

My 1918 Heliar 21cm barrel lens f4.5 will not focus: I get it near to focus then blurriness reappears if the bellows are racked in front or behind that best point. Highlights in particular yield an aura or coma (?) around them at maximum sharpness.
Bellows draw is not the problem, lots of that (Graphic View II).
The lens is free of haze and fungus, but a few small scratches are in front and back. I cleaned what I could and did a mag-lite test directly through it and no real fog looking through from an angle.
The saturation and contrast are fine.
I thought maybe it's a portrait lens but pretty extreme for even a Bob Guccione.
There is a pinpoint in focus which is where I focussed the object on the ground glass, but it should not have a depth of field shallower than an AEro Ektar, which is how it looks. I'll post an example anon.
Taking it apart the front two elements are cemented as per Heliar design, with no separation I can see; the middle biconcave piece is next forward of the diaphragm (iris) and it looks fine. Last there is the aft group is the two cemented rear elements with no separation.
I notice immediately to the rear of the iris is a screwed-in ring which is CROSS THREADED and thus not level with the axis it should be on.
I'm not sure its function as it does not abut anything. I wonder though if it's a stop to limit the amount of screwing-in of the rear group of the two fused elements. Doubtless someone has tinkered with it.
I tried focussing on the GG while screwing in the front and rear groups to varying degrees but no difference.
The helicals of the threads front and rear have only one engagement point. I read somewhere that comes into play, say, in disassembling front-focus folders and making sure you get the two threads to re-engage relative to each other for the purpose of not screwing up focus versus the rangefinder's (something about some threads having more than one point of entry to each other).
Sorry to be long winded but I thought it would save time to tell others what I've already considered.
Who could assess and treat such a condition, SK Grimes?
What are your thoughts, please?
Thanks.

Jon Archibald, Peterborough Ontario Canada

 

[Kirks518]

From what you're describing, it does sound to me like a flipped element. I had the same problem with a Mamiya TLR lens (there was a url link here which no longer exists). If you don't know which element was flipped, it will be a trial and error type of fix, but it can be corrected.

 

[Kirks518]

I would flip the rear element group, and see if that fixes it. From what I can find, it looks like the rear group is the only group that could be flipped and not be obviously flipped when just looking at the lens.

 

[shutterfinger]

According to A Lens Collectors Vade Mecum the Heliar is a group of anastigmat lens.
The f4.5 series has an angle of view of 50°.
This is the layout of the 21cm f4.5 of that era.

 

[Ian Grant]

I have a Linhof 150mm f4.5 CZ Tessar, almost mint that's unsharp it will focus but isn't capable of sharp negatives, it appears to be untampered with. I think the odd lens left the factory with issues perhaps by mistake.

Ian

 

[shutterfinger]

Zeiss Tessar layout

 

[aeyb701]

Thanks all for your advice.
I flipped the rear element and nothing changed, except the concave part faced out to the rear, and the concave surface in, different from all accepted Heliar lens diagrams I've seen.
I have been able to separate the front groups into the two diagramed parts, which are the front two cemented bits as one, and the middle but in front of the diaphragm biconcave piece. Then there is the rear group of two elements cemented as one. I wonder if they're all in some wrong relation to each other.
I did manage to make a small scratch in the glass using what I considered my spanner, but it's peripheral and won't affect the image, I expect.
I know it's been apart before since a ring behind the aperture is cross threaded, but no glass comes in touch with it, except maybe it controls the depth to which the rear group can be inserted. On the other hand I don't think that group can go in any further.
I may send it to Focal Point, John Van Stelton in CO. I already sent him my Rollei 2.8 front piece for a clean up of haze and/or fungus. What would anyone now suggest?
Thanks,
Jon Archibald

 

[RSalles]

Hi Jon,
SK Grimes would be my first bet, as you cited above.