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#1
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8X10 B&L ZEISS PROTAR SERIES IV info needed
Hi Guys,
Recently I bought this lens, the seller's description was vague and picture was too small... and I was hoping it was a 8x10 Series V protar, since I know a 183mm Series V would cover 7x17. But after the lens arrived I found out it is a Series IV 8x10. I could not find much information about the Series IV on the web, except that it covers 100 degrees at smaller apertures (f45?), and the focal length of a 8x10 Series IV is about 195mm. Will this lens cover 7x17? I don't have a 7x17 camera yet to test it myself right now... In general, how Series IV Protars compare to Series V Protars, in terms of contrast, sharpness at the edges and etc? Thanks a lot! Wenbiao |
#2
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8X10 B&L ZEISS PROTAR SERIES IV info needed
wrote in message ps.com... Hi Guys, Recently I bought this lens, the seller's description was vague and picture was too small... and I was hoping it was a 8x10 Series V protar, since I know a 183mm Series V would cover 7x17. But after the lens arrived I found out it is a Series IV 8x10. I could not find much information about the Series IV on the web, except that it covers 100 degrees at smaller apertures (f45?), and the focal length of a 8x10 Series IV is about 195mm. Will this lens cover 7x17? I don't have a 7x17 camera yet to test it myself right now... In general, how Series IV Protars compare to Series V Protars, in terms of contrast, sharpness at the edges and etc? Thanks a lot! Wenbiao Is this a Zeiss or a Bausch & Lomb Protar? Zeiss discontinued the Series IV very early and I can't find info on it in my 1920's Zeiss catalogues. Bausch & Lomb, who built Zeiss design lenses under contract, continued to make the Series IV until the 1940's. The Series IV is a medium-wide-angle lens. My c.1912 B&L catalogue gives the focal length of the 8x10 version as 7-11/16th inches. B&L claims a coverage of greater than 100 degrees for this lens but 90 degrees is probably closer to the mark. A 90 degree lens will cover an image circle of about twice its focal length at infinity focus so this one should work even if its coverage is a bit less. -- --- Richard Knoppow Los Angeles, CA, USA |
#3
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8X10 B&L ZEISS PROTAR SERIES IV info needed
Richard, Thanks for the reply.
The text on the lens are "8x10 Bausch & Lomb-Zeiss Protar Series IV PAT. JAN 13 1891 No.9151xx" I assume 1891 is not the date the lens was produced? I read the past posts (some of yours), that B&L did not begin to produce Protar lenses until 1900s, and after 1910 the patent law required the exact patent number printed on the lens instead just patent dates. So I guess this lens was made between 1900 and 1910? On http://www.cameraeccentric.com, the B&L 1910s' catelog (same as yours?) The same lens covers 8x10 at f12.5 and 10X12 at smaller stops. http://www.cameraeccentric.com/img/i...chcatb/p29.jpg On the B&L 1920 catelog, the same protar IV lens with 7 11/16 focal length, covers 6.5X8.5 at f12.5, and 8x10 at smaller stops. http://www.cameraeccentric.com/img/i.../coveragef.jpg So, I guess B&L became more conservative about their lenses' coverage later on? Any idea on the performance and characteristic diffrences between the V and IV protars? Thanks, Wenbiao Richard Knoppow wrote: Is this a Zeiss or a Bausch & Lomb Protar? Zeiss discontinued the Series IV very early and I can't find info on it in my 1920's Zeiss catalogues. Bausch & Lomb, who built Zeiss design lenses under contract, continued to make the Series IV until the 1940's. The Series IV is a medium-wide-angle lens. My c.1912 B&L catalogue gives the focal length of the 8x10 version as 7-11/16th inches. B&L claims a coverage of greater than 100 degrees for this lens but 90 degrees is probably closer to the mark. A 90 degree lens will cover an image circle of about twice its focal length at infinity focus so this one should work even if its coverage is a bit less. -- --- Richard Knoppow Los Angeles, CA, USA |
#4
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8X10 B&L ZEISS PROTAR SERIES IV info needed
wrote in message ups.com... Richard, Thanks for the reply. The text on the lens are "8x10 Bausch & Lomb-Zeiss Protar Series IV PAT. JAN 13 1891 No.9151xx" I assume 1891 is not the date the lens was produced? I read the past posts (some of yours), that B&L did not begin to produce Protar lenses until 1900s, and after 1910 the patent law required the exact patent number printed on the lens instead just patent dates. So I guess this lens was made between 1900 and 1910? On http://www.cameraeccentric.com, the B&L 1910s' catelog (same as yours?) The same lens covers 8x10 at f12.5 and 10X12 at smaller stops. http://www.cameraeccentric.com/img/i...chcatb/p29.jpg On the B&L 1920 catelog, the same protar IV lens with 7 11/16 focal length, covers 6.5X8.5 at f12.5, and 8x10 at smaller stops. http://www.cameraeccentric.com/img/i.../coveragef.jpg So, I guess B&L became more conservative about their lenses' coverage later on? Any idea on the performance and characteristic diffrences between the V and IV protars? Thanks, Wenbiao My catalogue is a bit different from the 1910 one on the Camera Eccentric site. I am guessing at the date based on a list of cameras using B&L lenses included in the catalogue, I think it may be older. B&L was considerably more liberal than Zeiss in their coverage claims often giving the "small stop" coverage only where the Zeiss catalogue lists coverage with lenses wide open. "Small stops" usually means f/45. I miswrote about the expected coverage of this lens, it will _not_ cover 7x17. The image circle at infinity will be about 16 inches, I am not sure what I was thinking about but had not had my morning coffee yet. The basic design of the IV and V are the same. Both are essentially Paul Rudolph's original Protar design but made to have larger coverage by making them slower. The Series V Extra Wide Angle lens, which will cover at least 105 degrees, is only f/18 wide open and must be used at f/45 for maximum coverage. In general, this type of lens has good performance but Rudolph abandoned it for other designs, notably the Tessar and Planar, which were capable of better performance-- but NOT as wide angle lenses, where the Series V continued to be made until the 1940's, maybe later. The famous Convertible Protar has four elements in each half, essentially each is a cemented version of the earlier lens with all four elements cemented. However, the performance of a single Convertible Protar cell is not as good as the older type. The US government ruled that products made from 1927 must carry the actual patent number rather than just a patent date; there were just too many patents being issued. However, may products made earlier had patent numbers on them so this is not by itself a sure way of dating. The name Bausch & Lomb - Zeiss is somewhat better: the agreement between Zeiss and B&L ended with the outbreak of WW-1 in 1914 so lenses marked with this trade name were made no later than 1914 or 1915. B&L continued to make Zeiss design lenses with Zeiss names until the 1950's, particularly the Tessar, Protar, MicroTessar, and a couple of others. I have never found a key to B&L serial numbers other than a partial key to late ones. It appears that each type of lens had a separate serial number sequence. For instance I have a list of numbers for the Micro Tessar which could not possibly fit B&L's regular Tessars. I have been looking for B&L serial number info for a long time and not found anything. I suspect that B&L's old business records no longer exist so, unless someone has lists the info is probably lost. Before about 1941 B&L used all numerical serial numbers, after 1941 they began to use a two letter prefix. Unlike the Kodak serial number prefix, which is a date code based on the key word CAMEROSITY the B&L code indicates the class of lens and year of manufacture. The letters are not in order so one must have the key. I also don't know for certain what the colored dots found on some late B&L lenses mean. In any case, your lens was made before 1915. The date is the date of the patent. In the US patents, until very recently, had a life of 17 years and can not be renewed. Because some foreign patents are granted for a period of 20 years the US patent law recently was revised to allow recognition of this. There is nothing to prevent the indication of a patent on something after the patent has expired. The Protar was the first lens to employ the "new" Jena glass types to form an anastigmatic. Originally Zeiss called the lens the Anastigmat but the name proved impossible to protect so it was changed to Protar. At the time the lens was designed it was thought that it was impossible to make a lens which was simultaneously free of astigmatism and color corrected with the conventional glass types available before Barium and other new glass types. In fact, this was not true but such a lens was not designed until _after_ the new glass types became available. Martins, of Busch (I think) designed a four element air spaced lens that was both anastigmatic and color corrected using only old type glasses. I am sure this is more than you want to know. :-) -- --- Richard Knoppow Los Angeles, CA, USA |
#5
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8X10 B&L ZEISS PROTAR SERIES IV info needed
Richard,
Thanks for the detailed message, this is exactly what I was looking for. Whenever I buy a lens or a body, I would like to know the detailed history about it, usually searching for old posts (some are yours and some are from other people) will give me what I want to know, but your replies to my question are what I am looking for this time. And it is good to know (first time too) that anastigmat lens can be made from old glass type. One more question: since the patent date on my lens is 1891, and from what you said: that a patent has 17 year life span, and doing the math, it seems that 1908 will be last year B&L needs to/can print this particula patent on a Protar lens? I mean, after 1908, B&L does not have to "obey" this patent anymore? (I read it somewhere on the net that the original protar lens patent was made in 1890 or 1891?) In other words, this particular lens was made before 1908? Thanks again for your detailed and very informational reply. Wenbiao |
#6
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8X10 B&L ZEISS PROTAR SERIES IV info needed
wrote in message ups.com... Richard, Thanks for the detailed message, this is exactly what I was looking for. Whenever I buy a lens or a body, I would like to know the detailed history about it, usually searching for old posts (some are yours and some are from other people) will give me what I want to know, but your replies to my question are what I am looking for this time. And it is good to know (first time too) that anastigmat lens can be made from old glass type. One more question: since the patent date on my lens is 1891, and from what you said: that a patent has 17 year life span, and doing the math, it seems that 1908 will be last year B&L needs to/can print this particula patent on a Protar lens? I mean, after 1908, B&L does not have to "obey" this patent anymore? (I read it somewhere on the net that the original protar lens patent was made in 1890 or 1891?) In other words, this particular lens was made before 1908? Thanks again for your detailed and very informational reply. Wenbiao I don't think there was anything in patent law to prevent the printing of patent information on a product after the patent has expired. Its quite possible the lens is that old (1908 or before) but in the absence of serial number data I don't know of any way to prove it. A good source of general information about old lenses is _A History of the Photographic Lens_ Rudolph Kingslake, 1989, San Diego, the Academic Press ISBN 0-12-408640-3 This is out of print but is sometimes available used and good libraries should have it on interlibrary loan. -- --- Richard Knoppow Los Angeles, CA, USA |
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