English lenses?greenspun.com : LUSENET : Large format photography : One Thread
I have two English lenses I would like comment on; 1)Dallmeyer anastigmatic wide angle foc.ln.41/4 inches f 6.5 mounted in a Compur shutter so lens is in front of shutter.care must be taken to keep the iris associated with the shutter wide open. 2)ALDIS triple convertible foc.lns 5.1/4 ,8 1/4approx.2x engraved on it 11.1/4 approx. 4x engraved,all f/ls in inches.Terrible shutter,self cocking,Universal.
-- James Tremills (email@example.com), May 26, 2001
I'm not sure what you are looking for but here are a few comments.
The lenses are probably old--no surprise! I think Aldis stopped producing lenses around 1920 and the anastigmat design was developed by Paul Rudolph of Zeiss during the 1890's. I think Zeiss licensed the design to Dallmeyer, but I'm not clear on the exact history. Dallmeyer invented many early lens designs (including the Rapid Rectilinear) and he or his son may have developed their own anastigmat. In any event, the design was an attempt to control astigmatism, one type of lens aberration.
Older lenses are typically uncoated and produce images of lower contrast. They are more prone to flare and should be checked for decementing, fungus, and other age-related problems. They are not going to be as sharp as a modern lens but can produce nice images with appropriate contrast controls and limits on the size of your enlargements. They also tend to have less coverage than modern lenses and will reduce the extent of camera movements.
I would guess that the Dallmeyer was remounted in a Compur shutter. I say this because most lenses are mounted with the shutter between the front/rear elements and the Compur is probably much newer than the lens. I'm not sure if this will cause a problem, but be aware that lenses are designed with specific distances between the front and rear elements. If a lens is remounted this distance should be maintained. Check to see that the lens focuses and measure to see if the remount has changed the focal length of the lens.
I don't have any specific information on Aldis or his lenses. According to Kingslake, Aldis worked for Dallmeyer until he establihed his own firm in 1901. I've seen listings for Aldis Anastigmats but only one brief note on convertible lenses. Kingslake notes that Aldis produced a convertible stigmatic lens called the Carfac. Produced in 1910, the lens claimed to be convertible with the front component having 3 times the focal length of the combined lens. Kingslake also notes that the rear element of the Carfac had a focal length of 1.5 times the combined system. I would guess that the Adlis lens works like most older triple convertibles (Turner-Reich, etc.). The focal length is 5.25" with all elements combined. The rear cell (alone) produces a focal length of 8.25" and the front cell (alone) yields a focal length of 11.25". I would guess that the coverage of the lens increases as you move from "combined" to "rear" to "front." How much? Probably from 4x5 to 8x10 but I would do some tests with paper negatives. Also, be aware that the quality of convertible lenses usually degrades as the elements are reconfigured.
I hope this information is helful to you.
-- Dave Willison (firstname.lastname@example.org), May 29, 2001.