Help Needed to Identify Vintage Dallmeyer Lenses?

[westlandscout]

Hello
Just started buying vintage lenses and have just come across a mystery item....
Its a thick aluminium lens board featuring 2 lenses, both slightly different and both marked "J.H.D" which I assume to be Dallmeyer? Both lenses have 2 big knurled adjustment wheels for the aperture.
One has "J.H.D 745532" and the other has "J.H.D 756915 140mm "P M I" 8063".
Other than the markings around the lenses there is no other marks present to give a clue as to what it was made for.The board measures 6.25 x 3.5 inches.
Any clues would be helpful.
Regards
Simon.

[dsphotog]

Either for stereo photography, or passport/ID shots.

[Steven Tribe]

Guess would be:

Battle field/Target stereo set for military camera design. Stereo photos were much used by the RAF and shown in use in an episode in the BBC's "Foyle's War".

Dallmeyer, like other UK companies, contributed many types - mostly with the AM "crowsfoot" stamp but sometimes without.

This is heavy duty and has the common locking grub screws to counter aircraft vibrations.

If the two numbers are genuine Dallmeyer serial numbers, then we are well past WWII and into the cold War. "PMI" is a clue I can't decipher!

[westlandscout]

Hello
Thanks for your thoughts so far, in some ways I am pleased that there is no quick answer. I agree with you Stephen that this does look industrial/military but the distinct lack of markings is a mystery. The passport /ID card idea is also interesting. I did wonder if it had something to do with microscope photography?
Keep your thoughts coming in!
Simon.

[dsphotog]

The next question is what camera was it used on?
It would need some kind of shutter in the system.

[Steven Tribe]

Lens used for special purposes are often very poorly marked - there is just a single buyer!

It might be an idea:

- to get an idea of the lens structure. Quite a few late Dallmeyer lenses have a quite wide following (money!).

- to browse through the post-war section of the Lens Vade Mecum on Dallmeyer. Dallmeyer was running out of names for designs, so one series was called "Rareac"!

[westlandscout]

Hello and thanks for the posts. I will get the Lens Vade Mecum as you suggest Steven, I have browsed through hundreds of photographs of single Dallmeyer lenses and nothing looks like either of them. It sure is a mystery!

[Mark Sampson]

Just for the record, aerial stereo images are made by having a 50% image overlap on adjacent frames, so double lenses are not used. What Mr. Tribe calls the 'crowsfoot' is actually the 'broad arrow' symbol that has been used by the British government since the 1700's at least. (The story goes that there are still trees in the forests of Maine, USA, that were blazed with the broad arrow before the American Revolution of 1776; having been chosen as material for the masts of the ships of the Royal Navy.) About your mystery lenses, though, I am utterly ignorant.

[Steven Tribe]

That sounds very sensible. The seperation between the "2 lenses" is created by the aircraft moving quite a few meters in the 1/30 sec. between exposures.