Wollensak 14", projection lens? What formua?

[Wenbiao Liang]

I got one of these lenses, looks like a projection lens to me, chrome barrel, no iris, but with a focus mechanism. The text on the barrel is: 14" EF WOLLENSAK - ROCHESTER U.S.A.

The interesting part is: after I took it apart for cleaning, I found out that it has 2 groups, one group has 2 cemented elements (a thick one and a thin one, at least from the rims of the glass. ).

The other group has 2 elements, but not cemented, the inside element is a positive element (thinner), and outside element is a negative (thicker). The 2 elements are very close to each other, actually the outside glass rims of the 2 elements are touching each other, almost like they could be grouped together.

Here is a picture of it.
http://s94121683.onlinehome.us/images/lens/PIC00003.jpg

The dia of the front lens glass is 1 7/8", but there is also a metal ring, so effective openning is 1 1/2, that will put it at f9?

My question is: What formula of this lens can be? Petzval? Rapid Rectilinear?


Thanks,
Wenbiao

[Ole Tjugen]

A Rapid Rectilinear has two cemented groups, and is not "rapid" by today's standards (f:7.2 is about the optimum). So that's not it.

Yours sounds like a Dallmeyer-type Petzval, where the rear elements are reversed compared to the original Petzval patent.

[Michael Gudzinowicz]

It certainly looks like a projection lens for 35mm or 2x2". Most of these lenses in "long" focal lengths for the format are simple telephotos. In your case, the design may be a triplet (front three elements) with a rear negative element added to achieve the tele effect. Focus a lamp filament on a distant wall using the lens and see if the lens or front of the lens to filament distance is significantly less than 14" plus required extension. I've used the rear negative element of projection lenses behind LF Tessar lenses to make simple telephoto lenses for LF use.

[Ernest Purdum]

I agree with Ole Tjugen (I'm not sure I'd be brave enough ever to disagree with him)that this is in all likelihood a Petzval variant. Since Petzvals are quite sharp over a limited central range, they were quite commonly used for projection for a very long time. They are, of course, progressively soft towards the edges. For this reason, and because soft focus lenses have recently become rather expensive, these projection lenses have been searched out by experimenters to use as taking lenses. This isn't altogether new, however. I have a book on portrait techniques which references two professional portrait photographers using them. Neither had made any attempt to reduce the maximum asperture but were using them wide open.

[Wenbiao Liang]

Thanks Ole, Michael and Ernest, for your replies. I appreciate them.

This weekend, I "mounted" the lens (by holding it) in front of my Speed graphic and I had to crank the bellows all the way out to focus though. On the ground glass it is kind of low contrast (6 glass air surfaces), and when I "tilt" the lens so that I could see what the edge of the illuminated area would look like, I did see the "swirl" bokeh that is "typical" of a Petzval lens.

So, I guess this is indeed a Petzval forumla? Now I need to figure out how to cut a slot for "waterhouse" stops... I am good at woodworking, but not at all at metal works...

Thanks again!

Wenbiao

[Michael Gudzinowicz]

You're lucky to have a Speed so you can play with all sorts of odd lenses. If the lens requires 14" of extension, it's very likely a Petzval, and the pupillary magnification should be around 1. I use thin high speed metal cutting disks on a table saw to cut slots in lens barrels. Wear eye protection, and remove the glass from the lens.

[Wenbiao Liang]

I went trickle treat tonight and instead of candy, I got several lenses back. No, actually it just happens that a lot of lenses I bought arrived tonight.

One of this huge barrel lens has no name on it, only a hand written EFL 164.7 S/N 10xx, I guess this means the focal length is about 165mm.

The aperture scale goes from f8 to f45, there are 18 aperture blades forming a perfect circle. The lens is huge, the barrel is 80mm in diameter, the outter diameter of the glass is about 60mm, glass is coated.

The front and back groups unscrew easily, and diameter of the lens screw mount is about 53mm, so smaller than Copal 3s I guess.

I think this is a process lens of some sort, the question is: what brand and make?

I google'd "165mm f8", and most of the results are super angulon, but from the look of the glass it is not a Super Angulon type, when I look into the glass, I don't see the "small bubble" that is typical of a super angulon. I see 3 small reflection points and a big one, but the outter glass is so deeply curved, it is hard to see its reflection, maybe 3 elements?

The inner lens glass diameter is big as well, about 40mm in diameter, the aperture blades are stopped at f8 mechanically. At f8, the hole size is only 15mm, less than half of what it could be, the lens mount hole size is about 37mm.

Here is a picture of the lens.
http://s94121683.onlinehome.us/image.../PIC000020.jpg

Anyone knows what this lens is?

Thanks!
Wenbiao

[Wenbiao Liang]

Another mystery lens in the lot is a brass lens, the text on the barrel is:

R.R
6 1/2 X 4 3/4
G. Knight
SOUTHSEA

There is a f/16 water house stop, also made of brass I think.

I think R.R means Rapid Rectilinear, 6 1/2 X 4 3/4 means it is half plate?

The question is: what is the focal length, and what is the maker? I google'd a little bit, and there seems was a G. Knight photographic dealer in NY early last century, but I assume it is a dealer only, not the manufacture?

Thanks!
Wenbiao

[Paul Fitzgerald]

Wenbiao,

"I think this is a process lens of some sort, the question is: what brand and make?"

That look quite like a JML process lens, usually super sharp.

Have fun with it

[Ernest Purdum]

Regarding your brass lens, You are, of course, right that R.R. means Rapid Rectilinear and 6 1/2 X 4 3/4 means 1/2-plate. The way the size is expressed is indicative, or at least highly suggestive, of British origin since American usage places the smaller dimension first. Unfortunately, the only British G. Knight listed in the British Camera Makers book is a George Knight in London. Your G. Knight was very likely one of the many photographic dealers that had their names put on lenses for other sources.

I can't help with the focal length either, since this varied with different makers.

I'm glad you got a Waterhouse stop. More often than not all of them are missing. I hope you got a flange , too.

Have fun with all your toys.