Brass rectilinear lenses

[Neil Purling]

Now these old lenses were often marked with the plate size they would cover.
Is it to be assumed that where any old rectilinear/aplanat type lens is marked with a plate size rather than focal length it covers the stated size at its widest aperture?
Such advertisment material as I have for R&J Beck shows that as you stop down a f5.8 or f8 rectilinear coverage increases somewhat. Does this also happen for the little f16 wide-angle aplanats?

[Rob_5419]

Now these old lenses were often marked with the plate size they would cover. Is it to be assumed that where any old rectilinear/aplanat type lens is marked with a plate size rather than focal length it covers the stated size at its widest aperture?

At least in my experience, this is correct: the stated coverage is for plate size at full-aperture yet most of the plate-marked lenses also have a precise indication of their focal length i.e. 7.65 inches. This is more likely if it came from a reputable manufacturer, like Taylor & Hobson who were particularly meticulous in their manufacturing and detailing of lens focal lengths. As you know, no two brass lenses are the same: Taylor & Hobson regularly produced 7.65 inch focal length III series lenses, and then 7.70 inch type III series - you may find more variations of focal lengths than similar focal lengths.


Everything I've used, from early half-plate triplets, 12" rectigraphs and homocentric lenses all cover their stated plate size for the brass types. Once you get into the waterhouse type aperture lenses, this equally applies - the calculation was done on the full aperture (i.e. no waterstop).

I think this is one reason why the covering power was understated to some extent although that's retro-speculation only. A caution though: once you get into wide-angle brass lenses (for instance - 5 1/4 inch - 6 1/2 inch for 1/2 plates ) their coverage is more or less exactly as described.

When I stop down a brass lens with a standard focal length, the coverage of some (diminutive) lenses seems huge and can outlast the camera movements (15 degrees rear swing, 30mm front shift and 10 degrees front tilt). Admittedly, the most limiting factor on my half-plate/plate cameras tend to be the cameras limited movements - not the actual lens.

PS - f16 aplanats - I'm not sure. I'll have to test it. I am very careful using small apertures because I can't see much of an image on my ground glass due to the small aperture. For that reason I mostly shoot wide open.

[Neil Purling]

Well, I would have thught the wide-angle aplanats would be used pretty near to wide-open.
At what point does diffraction start to degrade the image?
As I have a 6" f16 Wray said to cover 8"x10". R&J Beck's 6" f16 wide-angle aplanat is stated to be for 8x10. The no-name lens I have will probably be of 5" focus.
I have two other aplanats: A 6" f5.8 Beck and a B&L off a old Kodak of approximately 5" focus.
All my aplanats must be of pre WW1 date, although I aren't 100% sure about the Bausch & Lomb, which came of a 1a Autographic.

[Neil Purling]

I managed to find John Henry Dallmeyer's US Patent application #79323, but I can't print the thing out. Dated June 30th 1868 it is not symmetrical.
Has anyone chased the British patent of the same invention?

[Sven Schroder]

Hi Neil

I've seen the diagram in the kingslake book first patent was not symmetrical (changed to the symmetrical later) and I have an example of this lens its F15 and covers more and is marked J H dallmeyer 25210 No 1 Rectilinear Patent, I don't have pic of it at the moment. When I searched for info I found some wet plate photographers using it to be historically correct and paying good money for them.

regards
Sven

[Neil Purling]

The early patent says it is a 100 degree wide angle, as opposed to wide field.
I don't know what coverage would have been of the original.
The lens assumed at least three forms: extra fast (f5.8), normal (f8) and wide-angle.
It sounds like your lens is the wide-angle symmetrical version like the pair I have.
Sven: Your lens sounds like the wide-angle form that traded speed for angle of view & wide field. What do you shoot? With that type a 3" was for 4x5 and 6" for 8x10.

[Neil Purling]

Hey, I just received the 6" Wray WA aplanat through the post. It is asbolutely tiny.
It's such a surprise how compact a lens the WA rectilinear is.

[Sven Schroder]

Hi Neil

Just dug the Kingslake book out "Dallmeyer's patent showed a lens that was manufactured and sold under the name Wide-angle Rectilinear." the patent is
U.S. Pat.79,323 , Brit. Pat. 2,502/66 also two forms are shown in the diagram the unsymmetrical (my example U.S. pat. 79,323) and the symmetrical and more common RR. While my example is not inscribed Wide-angle rectilinear it has plenty of coverage for 10x8 at 6inch Focal lenght and the rear element is smaller than the front. Its not a later WAR, they are much more compact like you're Wray.
So enjoy the little Wray
Sven

[Neil Purling]

The little Wray lens is actually physically smaller than the 35mm LTM Jupiter 12 wide-angle.
I need to get a tight fitting slip-on lens cap and a lens panel with a Copal #1 hole.
Anybody got a beat up Linhof or Pacemaker Graphic lens panel with this sort of hole as the flange will fit the hole.
All I would need to do is drill the plate for the screws. The screws themselves would need counter-sunk heads. When the lens screws tightly home in the flange there is a screw hole just under the stop wheel.

[Gene McCluney]

All I would need to do is drill the plate for the screws. The screws themselves would need counter-sunk heads. When the lens screws tightly home in the flange there is a screw hole just under the stop wheel.

Unless that lens just has three screwholes in its flange, you don't need to use every single hole to effect a solid mounting, if getting a screw under the stop-wheel would be difficult.

[Neil Purling]

John Henry Dallmeyer's US patent 79323

http://www.google.com/patents?vid=USPAT79323&id=8bYAAAAAEBAJ&dq=John+Henry+Dallmeyer

Original unsymmetrical rectilinear.

[Ole Tjugen]

I've just had a 3 1/4" (about 80mm) Perken son & Rayment 5x4" "Optimus Portable" lens with me on holiday in Italy - used it on a 4x5" Speed Graphic. The largest hole in the aperture wheel corresponds to about f:11, the next is f:16. I assume the open hole is intended for focusing, and that it is not intended to use with bigger holes than #2.

Nice little lens - I'll be interested to see what the results look like!

[Neil Purling]

I would be interested to see some results as well, and so would a few of us.