I asked this question in response to a post about Ilex lenses, but now I'll ask everyone. I've looked at S.K Grimes website which has an article about the Ilex shutter for large format photographers which is pretty good. however I have an Ilex lens that I'm trying to find info on. It reads, 7" (180mm) f:4.8 Ilex Acuton No. 196. Its in a copal No. 1 shutter. It takes fantastic photos and is pretty clean. The shutter however, is a little tacky, with some blistering of the paint around the synch post and some rust on the back of the shutter cocking lever. The lens looks like it was made in the late '50s to mid- '60s. It also has a removable set of elements at the back and on the shutter body are two sets of f stops. One for 300 and one for 180. this leads me to believe that this is a convertable lens, but which is which? Or is there a missing set of elements to make this a 300mm lens?

Thanks for your input and time.

Marcus J. Wilson Sr.

-- Marcus J. Wilson Sr. (marcus.wilson@dtra.mil), October 25, 2000

Answers

I recommend that you write directly to S.K. Grimes--he really is the expert on old shutters.

-- Ed Buffaloe (edbuffaloe@unblinkingeye.com), October 25, 2000.

Perhaps you could check if the front and rear elements are inscribed with their individual focal lengths. It is possible that the single elements are of 300mm focal length each and the combination of the two elements is 180mm. This could quite easily be checked out with a test on the camera.

Simply focus the complete lens on an infinity subject and measure the distance from the lens flange to the ground glass and similarly with the front element removed. If my guess is correct the measured distances will correspond at 180mm and 300mm respectively. The Ross combinable lenses worked on this principle, so it is quite possible that this one does also.

-- John (jcr@jcr-cameras.com), October 25, 2000.

Hi Marcus, In the January/February 1996 issue of View Camera is Part Three of History of Lens Design by Lynn Jones. From this article I would guess that your lens is late 60's and was designed to be convertible by removing the front elements. It is a plasmat design, and the Acugon denotes marketing by Burke and James. Coverage is about 77 degrees and "performance was truly impressive."

-- Chauncey Walden (CLWalden@worldnet.att.net), October 28, 2000.