is Upgrading from Heliar to Universal Heliar possible?

[plaubel]

Dear specialists,

are there different constructions/lens groups , or is it approximatively able to change the Heliar into an Universal Heliar out of the original and fixed lensgroups?

Thanks,
Ritchie

[Steven Tribe]

In theory, yes. In practice, quite difficult.
First you have to have a genuine Heliar. The so-called "Heliar" was replaced by the Dynar lens design pre-ww2, whilst the Universal Heliar continued with the original optical design always.

The front cell of the Heliar and the central cell are joined together in a unit. It is frequently mentioned that the exact positioning of the central cell is vital to the performance of the Cooke triplet design. I know this first-hand as I attempted to modify a late projection triplet to work a la Universal, but I lost the positioning of the middle lens - which was a source of frustration!

I have some photos of the Universal double cell unit, which I needed to service some years ago. The brass is full of marks made by Voigtlander to ensure the mechanism worked without sticking!

The system means that there is an extra brass tibe thickness - meaning that the total diameter of the lens is greater than the normal Heliar of similar length.

Of course, it is possible to cut the ordinary double cell mounting close to the middle lens and remove most of the internal barrel of the cell mount up to the mounting thread. Then you would have to make a stop mount so the loose central lens doesn't go further down the barrel than the standard Heliar position. Then you would have to make a bearing to take up the slack between the inside of the barrel and the outer diameter of the mount of the central cell. Perhaps velvet would be OK? Finally, you would have to mount a brass slider (or perhaps two, one on either side!) which would run in two slots cut into the barrel's length. You could even engrave numbers which would correspond to the usual Universal graduations! The slot(s) would need to be covered with a dark cloth during exposure.

[Steven Tribe]

I need to modify my last comments a little!

I show the front section on a 36cm Heliar when screwed apart. As can be seen, the section where the central lens is mounted, the barrel is considerably reduced in diameter. This means that the barrel of the Universal could well be the same as an ordinary Heliar. It is also obvious that an extra ring is necessary to make a sliding fixture out of this section with the central lens!

[plaubel]

Steven, thanks to your suggestions !

So, at first, I would have to check the design of my 360mm Heliar.
Next, I have to understand what exactly happens while moving the Universal Heliar - the back lens and the middle lens stay in a precisely defined distance, and the front lens moves?
Maybe you could help out with a technical drawing of the Universal Heliar design?

And the lenses of both types are identically?
I am not only interested in a possible movement of the lens, I love the idea to have prints with an Universal Heliar look :-)

The rest sounds doable to me, my greatest "fear" has been a different lens design/lens types of my Heliar compared with the Universal .

Instead of internal brass sliders supporting and leading the movements, I am thinking of a normal thread with wide steps ( don't know the right word for this steps and their distances, which per example may have 10 steps per inch, or 3 Gänge pro cm).

In this case, no darkcloth would be necessary.

Ritchie

[cowanw]

It is the central lens that moves.
Have you seen this
http://www.antiquecameras.net/heliarlenses.html

[Steven Tribe]

Exactly the same lenses and the middle lens moves forward. The nearer it gets to the back of the front lens, the softer is the image.

Moving the middle lens forward needs quite a lot of precision engineering if you don't cut channels in the barrel.

[plaubel]

Moving the middle lens forward needs quite a lot of precision engineering if you don't cut channels in the barrel.

Now it is clear to me, thanks both.
I understand it requires deep thoughts about the engeneering, yes.
I am not interested in breaking the original body, if possible, but I remember that the middle lens did not come out alone...

Let me have a look at my Heliar, next.
Can I somehow find out the date of birth via serial number?

[Steven Tribe]

The CCHarrison "Heliar" web page shows the serial number/year table.

The photos I posted are from a 36cm serial number 99910.

I wish I had never read this thread and contributed as I think it is genuinely do-able! Perhaps someone at Grimes, or similar, would be interested?

[plaubel]

Steve, don't panic, I really love my lenses - thanks for reading, answering and contributing :-)

This idea lurks since years into my brain, and now I am interested in knowing more.
I think, I will give it a try, if my serial number is ok.


Ritchie

[Steven Tribe]

I am more afraid for myself and my 36cm Heliar.

The Universal I showed dismantled is just a 30cm version.