I have a Swiss lens which lacks direct information on focal length, a fate it seems to share with some other old lenses. It bears the inscription No 32955 E. Suter Basel Aplanat A No 3. I have tried to search the net to find the focal length, but so far without mentionable success. Now I wonder weather any of you experts would take the effort to open your fireproof archives and look this lens up in your Suter catalogue from anno domini ???? and see what you can find? I have found that this lens type consists of two achromats. Mine has a Compound shutter that needs some reviving. The aperture scale rates from F (!?), via 8 to 45. The glass seems to be in rather good condition.
What can I expect as picture taking caracteristics of this lens?
Suter Rapidaplanat Serie A, F/6, was made in 13, 21, 24, 30, 42, 48, 55, 65, and 90cm focal length.
From that it's a good guess that your No. 3 is a 240mm.
Sharp coverage is from 20 degrees at full aperture to 50 degrees at small apertures (general figures for fast f/6 Aplanats). Within this angle a good Aplanat (and Suter made GOOD Aplanats) is at least as sharp as an anastigmat of the same age.
Data from "Photographisches Hilfsbuch für ernste Arbeit" by Hans Scmidt, printed Berlin 1910. And also corroborated by my owh experience with a Suter Aplanat Serie B No.6 - 480mm and ultra sharp.
Thank you, Ole. Was it customary to use a "F" letter (bright and clearly written) on the aperture scale? On my specimen it says nothing about "Rapid" in the inscription, but it may have no practical implication, or were Rapidaplanat and Aplanat different constructions? I found somewhere a formula saying that
wide open aperture= focal length /diameter of the open "hole" when wiewing the lens from the front (here 38 mm). If the "F" on the scale means 6, this gives me a focal length of 228 mm, whereas a starting aperture of 6,3 (a more common number, as most of you know), gives 239,4 , which I regard as colose enough to 240!
Svein
Suter's Aplanats tend to have only Series and No. clearly engraved. Focal length and max aperture is something the original owner would have known when he pought it, which doesn't help us much a century later. The Serie A was the Rapid Aplanat, Serie B was the "universal" Aplanat F/8. Herr Schmidt sometimes wrote far more than the lens makers did.
Mine's got a very big and clear "F" on the aperture scale too. And lots of very clear numbers.
Focal lengths should always be taken with a lump (not grain) of salt. For most practical purposes, 228 is "close enough" to 240. The same goes for maximum apertures...
I've set up a little "Focal length measuring device" consisting of a long corridor with a window at one end and a sheet of cardboard on the other. I mark off the width of the projected image of the window on the cardboard, and compare this to the marks from lenses of "known" focal lengths. This simple "device" has proven remarkably accurate as I get more lenses for calibration. My best tool here is a "Vade mecum" type "Satzobjektiv", seven elements from 15 to 75cm focal length which turn out to be precise to within a few mm!
Ole,
you have spoken well of aplanats, so I got one for a good price and just cleaned it up.
It's 11 inch focal length measured. It has the above mentioned "f" and 8 through 44 nicely engraved. Also "Universal Rapid Aplanat" and the next line "Serie E" No 3."
Could this be a Suter? The only clues are how Serie is written, and the 8-11-16 ...scale.
I'll have to check when I get home in a day or two, but Suter lenses usually have the name engraved: Quality lens makers were known enough that they put their names on the lenses for marketing purposes. That doesn't mean that the nameless ones are bad, or that they are made by second-rate makers - only that they are less likely to be by Suter, Busch, Voigtländer, or Meyer.
"Serie" with that spelling indicates German, Swiss (as Suter) or Austrian. Which means I might be able to find out something once I get home - that's exactly what I have in my old (German) books. "E" is far enough out in the alphabet that a Serie E Universal Rapid Aplanat should be possible to find, especially knowing that a No. 3 is about 275mm.
Interesting and thanks for doing that. I can take pics or whatever will help too. It'll be interesting to do a shootout with my Dallmeyer Rapid Rectilinear of the same length. I just held them both up to the wall and could swear I see a diffence! I look forward to hearing back from you.
I think the original 'universal aplanat' was a Steinheil design using the then new Jena glasses. 'Universal' meant wide enough and fast enough for a broad range of uses. It seems to have then become a generic term for a Goldilocks Aplanat or Rapid Rectilinear, and many, many lens makers and re-badgers seem to have used it, especially in Germany. The 'Series E' might be a better clue as to the maker, but there my knowledge runs out.
It's quite hard to find information about Suter focal lengths online, but so far as I can tell the Aplanat B series follows the same ordering as the A series Ole posted. I have a Aplanat B No. 7 which is indeed around 55cm in focal length.
Here is a pic for fun. The glass is very nice, the aperature turn ring was knocked off track, but I fixed it. The lens now looks and works fine.
I'm waiting on an (appropriately named) universal iris mount so I can use more of these flange-less lenses.
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