I have all three suspects on hand, a 12" CE, a 14" Caltar and a 20" Ilex Acutar (is it the same as Ilex Caltar?), and upon flash light inspection, they all exhibit the same reflection pattern.
I have all three suspects on hand, a 12" CE, a 14" Caltar and a 20" Ilex Acutar (is it the same as Ilex Caltar?), and upon flash light inspection, they all exhibit the same reflection pattern.
One thing that should also be considered when we talk about lenses... how different samples of one same optic can vary in image quality. Back in the 1990s, I purchased a pre-owned 24mm-120mm AF Nikkor zoom lens. Its reputation only so-so at best. definitely not one of Nikon's better optics. Mine was a gem... used it professionally for years. Over that time I would visit the Photography store that I pretty much did all my business with. Whenever they had a 24mm-120mm AF Nikkor for sale, I would stop by with my lens and take both outside and shoot some frames with each lens down the same street. Probably tested a half dozen other 24mm-120mm AF Nikkors over the next dozen or so years and none (even the more modern models) came close to my original lens. As for LF lenses, only once I was able to test my lens against a similar lens that a friend owned. Same tripod, same scene, same film, same aperture, and same high quality film holders. Under a bit of magnification, my friend's lens was definitely sharper than mine. My lens I'd rate as very good, his I'd rate as excellent
If I'm not mistaken, the belief traces back to H. Lynn Jones, who claimed to have been involved in the creation of Ilex' last LF designs (Acugons, Acutars, Acutons).Originally Posted by mdarnton
See http://www.largeformatphotography.in...p/t-30957.html, which quotes and links to http://www.ilfordphoto.com/photocomm...?TOPIC_ID=7641
I went a little farther back. Ask www.archive.org to retrieve http://www.austincc.edu/photo/pdf/usdlens.pdf. Its a table of "Good buys in optics for large format" that Lynn Jones put together. It contains a few howlers, e.g., that tessars are convertible, and says this of the 508/7 Caltar (= Acutar):
This is a 3 element (Cooke Triplet Type) design. It was introduced in 1967 and was variable in quality through 1969. From 1970 until the demise of Ilex, these were superb for all formats through 8 X 10. The photographer should note, carefully, that the circle of illumination ( about 45o) is quite a bit greater than the 35o circle of excellent definition.
Is it possible that Ilex may have changed the design of the 20" Lens from a Triplet to a Tessar design, hence the claim that the earlier version were not as "good" as the later version? I mean so far I have not seen any one step up with a Triplet version of the 20" (with the reflection test).
Nah, Mr. Jones was referring to improved QC, not to a new design. He had quite a good career, did many good things but in his old age he seems to have gone off a little. He used to defend the canard that Goerz Americal Optical Company, originally the US branch of Optische Anstalt C. P. Goerz A.G. of Berlin is the same firm as American Optical Company.
If the people who've reported that their 508/7 Acutars' rear cells are cemented doublets are right, we have another instance of Mr. Jones being mistaken and sticking with it. That said and to be fair to him, I'd swear I've seen Ilex propaganda that said the lens was a triplet. But I can't find it, so could well be mistaken.
Well, I can't speak for Mr Jones, nor the Ilex Propaganda, but the rear group of my 20" Acutar is definitely cemented doublets. Just took it apart to look.
here is another Tessar claim from Donn in conversation with Kerry:
https://groups.google.com/forum/#!to...at/yhFgb_UW0JM
Thanks for posting the link. Mighty interesting conversation.
Posting Permissions
Reply With Quote
Bookmarks