Question Re: Wollensak Convertible Ia

[Kevin Crisp]

I've just picked up one of these. It is coated. In the front element, apparently inside or touching the glass, there are three evenly spaced shiny metal tabs. These look like the tape you'd use on splicing a reel to reel tape. They are just at the edge of the glass when the lens is wide open, folded over the edge so they point into the middle of the lens. It almost looks like they hold an element (or the element, if this is just like an all cemented Protar) in position. I've never seen any lens with something like this and was wondering if this is normal.

[wfwhitaker]

They're almost certainly spacers; thin shims to separate two elements. Is this a Velostigmat 1A? I've had a couple of these lenses, but never seen this, although I've seen it on other lenses.

[Kevin Crisp]

13" Raptar Series IA. If they are spacers then this isn't exactly a Protar copy. Thanks.

[Darren Kruger]

I've just picked up one of these. It is coated. In the front element, apparently inside or touching the glass, there are three evenly spaced shiny metal tabs. These look like the tape you'd use on splicing a reel to reel tape. They are just at the edge of the glass when the lens is wide open, folded over the edge so they point into the middle of the lens. It almost looks like they hold an element (or the element, if this is just like an all cemented Protar) in position. I've never seen any lens with something like this and was wondering if this is normal.

I just checked my 13" Series 1a Raptar and I didn't see any tabs on mine. When I had the lens serviced recently, the technician said the front set was cemented together.

-Daren

[Kevin Crisp]

Darren: So you get two reflections from the front and rear elements? This one gives three in front, so obviously the front element has an extra air space. Now why anybody would do that, I have no idea.

[cowanw]

You will think I am crazy (or not very well educated in these matters), but I see 5 reflections in both the 26 1/2" front cell and the 20" rear cell. A medium size weak, two small weaks and two large strongs, reading separately from the front for the front cell and from the back for the back cell. No tabs. Camera eccentric's 1957 catalogue describes this Raptar as a basic double Protar design.
Regards
Bill

[Bernard Kaye]

You are OK; your lens has been tampered with, four cemented elements were separated: black fabric (perhaps black paint) is between two or more elements that should be tightly cemented together. It takes a collimator to properly reassemble. You have a problem.
Bernie

[Kevin Crisp]

Well, I'm not OK. I took it apart. The first three elements have been recemented. They look physically centered but the job was sloppy (glue left on the edges) but not bad enough to separate and redo it. The back element, however, is not glued to the front three. Instead, somebody put three little tabs of Mylar (0.005" thick) to keep it from banging into the back of piece of glass #3 and then just put it all in the mount. This is why it has more reflections than the back element -- it has an extra air space.

I have tried to come up with an explanation of [I]why[I] somebody would do this. The best I can think of is that there was a partial recement of some elements, then the back one came apart and somebody who didn't feel comfortable recementing them figured clean off the old cement and put it together this way. They would not be connected but they'd be really close. Of course this really screws up the execution of the design, but maybe somebody didn't understand that. You can see the softness on the ground glass.

Anyway, the seller gave me $100 back as a credit, I can reattach the back element and it should be fine. Due to lack of bellows I can't use the front unit alone anyway (25"+ bellows needed) so as half a combined lens it should be fine. The seller just had the back professionally recemented and re-coated and it is very nice. This isn't so big a lens for a 360mm, I think I'm going to find it very useful. And I love Alphax shutters. Thanks for your comments.