Homemade lens - 200mm? /f 5.6 ? Former military item ?

luisalegria · Expire: 2018-01-18

I picked this odd thing up a while ago -

It is definitely a homemade M42 mount lens. It bears some strong resemblance in concept to another homemade Exakta-mount lens I picked up a few months ago -

http://forum.mflenses.com/what-the-heck-is-this-thing-200and-f-5-lens-t6488,highlight,penntar.html

The design is substantially different though, as the diaphragm is far from the optics on this one.

The mount is made of various bits, some of which i can identify - there is a series VI filter holder, the diaphragm holder is made from an old Kodak lens hood, and the M42 mount is an M42 reversing ring. I think the helical may be from a movie lens. The lens and lens tube, though, are maybe even more interesting. This is a heavy-duty piece of aluminum with a two-element optic, and under the black paint is a layer of olive-green. I'm guessing this used to be part of a piece of WWII US military optics (telescope, gunsight, surveying instrument ?), adapted as a camera lens, possibly in the late 1950's-early 1960's.

I remounted it on my bellows, as though the focusing mount works and gets to infinity, it is a little stiff and the minimum focus seems to be about 30 ft/10m.

As a lens, it is very interesting. It is quite sharp in the center, but it gets progressively worse towards the edges, with lots of chromatic aberrations and etc. It may not be coated at all, but with just two elements the contrast is just fine. It does flare badly pointing near the sun, but that may be because of some haze on the inner element.

The bird -

crop -

casualcollector · Posted: Tue Sep 30, 2008 1:36 am Post subject:

Cool!

orly_andico · Joined: 02 Jul 2008 Posts: 253 Location: Philippines

looks like it came off an M17 Elbow Telescope, which was used to lay 105mm howitzers and the like in World War II. I had one of these as a kid, and the barrel (plus the hole in the barrel..) looks familiar. The objective is around 50mm diameter right?

DSG · Joined: 04 Mar 2007 Posts: 544 Location: London, UK.

Again, like your other home-made aquisition, it seems the lens maker was after a sharp lens with good bokeh on a shoestring budget.
I'd love to see a 100% crop of the pigion to see how it compared with a 100% crop from a similar shot from my Sigmatel 135mm f1.8:

luisalegria · Expire: 2018-01-18

Hi Orly,

I went off to find an M17 elbow telescope of course, and naturally I found one. Isn't the Internet wonderful ?

http://www.usmilitariaforum.com/forums/lofiversion/index.php/t6367.html

It does look like it ! They must have sawed off the tube with the objective lenses.

As for pigeons - this is a bit better focused than the other, but I liked the expression on the one I posted

crop -

Now, these are from a 6MP Pentax K100D, so they aren't likely to match yours.

Attila · Expire: 2025-11-18

Looks pretty incredible to me !!

kds315* · Expire: 2021-03-09

Excellent results - congrats to that find!

I have a (some actually) military lenses made by Ernst Leitz Canada (ELCAN), mostly prototypes and I guess I should give them a try now that I see THAT....