Dallmeyer 3"=75mm Rectilinear Patent lens query

[NickL]

Hi,

I am trying to match some photos taken in 1907-8 with equipment accompanying a half-plate R J Beck camera now in the Oxford Museum of Science. The camera was used by T.E. Lawrence for castle & church photos, mainly in France. I think most of the photographs used the 7.25" Taylor Taylor & Hobson "symmetrical meniscus doublet" lens which is with the camera, but some would have needed a wider angle lens, and some a longer lens.

There is also a Ross 3.25" (86mm) F.16 wide angle anastigmat lens with the camera, but from the info I can find this wouldn't have fully covered half-plate or allowed room for adjustment. It is apparently more a quarter-plate lens (photos attached).

Another lens is engraved Dallmeyer London Rectilinear Patent with F=3"=75mm and No. 75287 on the rim. There is no iris. The serial number would put its manufacture date a little after 1902, which was S/No. 65,000. Can anyone shed any light on how this lens was used? e.g. is it a screw-on adaptor to modify the focal length of another lens with an iris? In the Dallmeyer box is a green filter of similar dimensions. There is room in the box for another lens or barrel body which might now be missing. It seems unlikely, but could the 3" could have been used with the Ross or TTH lenses (I would have to find out if the threads match).

Thanks for any assistance.

Nick

[NickL]

Additional photos:

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Nick

[nolindan]

The Wide Angle Anastigmat should cover British 1/2 plate. Apparently good for ~110 degrees, or a 245mm image circle; the diagonal of 1/2 plate film is 204mm, less with a margin around the film for retaining the film in the holder.

The 75mm rectilinear would not have covered 1/2 plate. The lens may have used waterhouse stops that slid in through a slot in the lens' barrel. It would not have been used with another of the lenses (outside of experimental circumstances).

[Steven Tribe]

Here is data for the 3 1/4 Dallmeyer - of which the Ross is a clone.
These were made for decades!
Possibly cover 1/2 plate but probably dark corners!

The 3” Dallmeyer rectilinear lens is just a single lens cell and the green lens is a early green filter, I think .
These items probably were in the casket in your last image. This casket set would have had an extra lens cell making up the 3” rectilinear set - plus either a landscape meniscus lens and/or a wide angle rectilinear. There would alsohave been a barrel section with an Iris. You can probably clear this up by counting the number of depressions/slots in the base of the casket.

[nolindan]

Here is data for the 3 1/4 Dallmeyer - of which the Ross is a clone.

The page is for the f11 version of the lens, the text above states that coverage may exceed 100 degrees at f16.

The native 86mm f16 lenses may then indeed have a coverage of 105-110 and cover 1/2 plate, albeit, as Steven said - "probably dark corners!"

Proof's in the pudding: Mount the lens in the camera, point it at something and look at the ground glass.

[NickL]

Gents,

Thanks for your contributions. The lenses shown are in a museum, so I'm a bit limited to what I can do with them. However, I've found a Ross 3.25" for sale so I could test the coverage of a later version of the same design (~1924 vs ~1905).

If I was buying a wide angle lens for a UK half-plate camera in about 1905 I think I'd chose the 4.25" rather than the 3.25", unless I was photographing cathedrals or similar & couldn't get further from the subject.

Nick

[NickL]

Can anyone shed any light on the purpose of these two items. There are in the leather box with the half-plate camera, dark slides, lenses, loupe etc. I haven't seen them in the flesh & only have the one photo showing them from the side.

They are described by the museum as "a copper alloy collar and a copper alloy tube painted black." The collar has a cut-out/notch. I don't think they contain lenses. I could only think they were an outer part of the Dallmeyer loupe. I can just see knurling/serrations on whatever is fitted onto one end of the tube

Thanks,

Nick

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