TWO mysterious lenses

[renes]

I bought these two lenses and have not found an information about them.

First one is Dallmeyer Finder Anastigmat 4" lens. It's in barrel, very small, seems a Cine lens but never heard "Finder" name under Dallmeyer.

Second one is marked only with A M letters with crown stamp in between - looks like englaring lens but nor for sure (see picture) and who is the maker.

Hope someone knows anything.

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[dave_whatever]

I think the AM means "Air Ministry" - i.e. a lens made for the British gov, probably for aerial recce work?

[Steven Tribe]

More likely ordinance/bomb sights or training/hit recording camera. There are some who have good knowledge of the various cameras used by the RAF. Most gun camera optics have grub screws to keep the cells in place due to excessive vibration!

[Roger Hesketh]

That looks like an f4 in the picture. The only lens with that maximum aperture, that I know of, that was made for the military, was the Ross 5" F4. However they are usually in a very different mount.

[renes]

That's right, it's 5" with f4 to f11 with 16 aperture blades. Both glasses are convex outside, really strong. Is it anastigmat? I see - if corectly - 2x 4 reflections.

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[Roger Hesketh]

It is a plasmat. One of the first. It is a moderate wide angle. Covers about 70 degrees. Will cover 5x7 . Perhaps a bit more. It is actually an f3.1 lens. It has an extra large front element. I think the idea was to even up the illumination on the plate. Civilian versions of lens are engraved E.M.I. I think it stands for Extra Marginal Illumination or maybe it is Extreme. Not sure which. They used them on the torpedo cameras and for aerial survey work. Seen from that angle the mount is of the type usually seen. It maybe possible to stop the lens down more than f16. Some you can, some you cannot.

[renes]

Confirmed, front lens is larger, 41mm in diameter what gives f/3.1. And aperture goes beyond f11, a few mm further.

Really fast WA vintage lens for 5x7! It's like 27mm on 35mm camera (lens equivalents for 5x7)?

[hoffner]

That's right, it's 5" with f4 to f11 with 16 aperture blades. Both glasses are convex outside, really strong. Is it anastigmat? I see - if corectly - 2x 4 reflections.

117706

It is a lens from a Torpedo camera. Google it to find all about it.

[jesse]

That's right, it's 5" with f4 to f11 with 16 aperture blades. Both glasses are convex outside, really strong. Is it anastigmat? I see - if corectly - 2x 4 reflections.

117706


It is a Ross wide angle lens.
http://www.ebay.com/itm/Ross-Wide-Angle-5in-f4-Barrel-Lens-152829-/261486032419?pt=Camera_Lenses&hash=item3ce1c83623

[Pete Watkins]

I agree with Jesse, it's a Ross 5 inch wide angle lens. I've got one just like it. Not all these lenses were marked by Ross to show that they manufactured them. The 14A shows that it is a lens made for a government contract and the AM indicates that it was for the Air Ministry.
I've seen an image in a book by St Ansel taken with one of these lenses so they can't be too bad.
Pete.

[renes]

Thanks to all for help in its indentification!

But what about "Dallmeyer Finder Anastigmat"? I have found nothing in Google apart from a few photos taken with it with its unusual/amazing rendering (some of the last at the site):

http://jorson.dyndns.org/ognn/viewthread.php?tid=37&page=164

[IanG]

The 5" f4 Ross WA Xpres was designed for 5x4 and 5x5 (aerial film format), it doesn't cover 5x7 and has an angle of view of 70º, at one time Ross claimed it would cover 6½x4¾ with an Angle of view of 80º but they later reduced this.

The AM military version was an aerial camera lens optimised for Infinity, unlike the standard Xpres WA it was restricted to f4-f11 rather than the f4-f32 of the regular version, Ross subcontracted some of the AM lenses so although based on a Ross design it may have been made elsewhere. The quality of some of the AM lenses isn't always as high as the regular production lenses.

Ian

[Carsten Wolff]

A.M. lens serial numbers starting with UU or WW are Dallmayer, WW are Ross AFAIK.

[analoguey]

I saw someone say they used a Dallmeyer Aerial lens recently - bought it in the UK for apparently 70 GBP - I was quite surprised to see a dallmeyer being so cheap - I thought they were all expensive!
So I suppose there were a lot of aerial lenses as well?

[Carsten Wolff]

I sold an old brass Dallmeyer 1aa, for less than that not long ago, but yes, unless they had something that made them special, a lot of A.M. lenses, no matter who made them, as well as many aerial Dallmeyers go cheap these days (and rightly so).

[Roger Hesketh]

Ian The lenses were used on Torpedo cameras which took four 6cm x 18cm photographs on 120 roll film. 18cm is a smidge over 7 inches. Stopped down past the marked f11 they will cover 5x7.

[Dan Fromm]

Roger, sqrt(60^2 + 180^2) = 190. The diagonal of 5x7 is 210 mm. Are you sure that the 5"/4 Ross will cover 5x7?

FWIW, I had one of those beasties years ago. I bought from Surplus Shed, who offered it as an enlarging lens. I shot it for trial on a Nikon since only central sharpness mattered for my application. Very sharp, even wide open, also very flary.

[IanG]

Roger, the image circle required for 6x18 is less than for 7x5 (as Dan points out), but it's only slightly larger than the 5x5 format Ross claim the lens covers at full aperture. One feature of the lens is it's sharpness at wide apertures.

Ian

[hoffner]

Just to be precise - the Torpedo camera back makes negatives of full 186 mm length.

[Roger Hesketh]

My apologies to you all. Firstly for the tardiness of my reply. I have been engaged organising care for my Mum who came out of hospital yesterday and also for misleading you. The lens used on the torpedo cameras whilst made by Ross and having a focal length of 5" was of a different design and had an f4.5 maximum aperture. Thank you Ian and Dan.