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on Oct 30, 2019 16:02:27 GMT
Posted: Oct 30, 2019 16:02:27 GMT
I had quite forgotten to mention 2 lenses that were proposed and prototypes manufactured but never made it into the Contax RTS Zeiss catalogue in the late 1970s:
Distagon T* 18mm f2.8 - 12 elements in 11 groups and used the Contax 70/86mm slip-on adapter to mount a dedicated 86mm slim filter, especially designed to prevent vignetting.
Distagon T* 25mm f1.4 - 13 elements (1 floating) in 11 groups and used a slim 86mm filter attached to a dedicated 90mm lens hood. This lens was designed to provide a wider option for the 35mm, 50mm and 85mm series of f1.4 lenses.
There was a much later lens designed and at least one prototype built which was an amazing beast; sadly, I only ever saw a photo of one attached to a RTSIII so never got to see it up close and personal:
PC-ApoDistagon 25mm f3.5 - I can't find the data for its optical formula but this perspective shift lens was huge and would have been quite a weight; you would have needed either the RTSIII or AX to balance it in the hand.
I'm not suggesting that they should necessarily be added to the list; I merely mention them for information and completeness... I know I still have the Zeiss Data Sheets for the 18mm and 25mm lenses somewhere here...
Thank you biggles3 ... I can always append the list with a separate group marked as prototypes. If you have anything in the way of datasheets, I can upload them to 'yashicaforums.net' and link them into the spreadsheet, just like the Zeiss versions are now. I'll PM you with an email address to use for any attachments you'd want to send. |
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on Oct 30, 2019 16:11:23 GMT
Posted: Oct 30, 2019 16:11:23 GMT
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on Oct 31, 2019 14:26:36 GMT
Posted: Oct 31, 2019 14:26:36 GMT
I don't know if this helps? link |
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on Nov 2, 2019 2:34:04 GMT
Posted: Nov 2, 2019 2:34:04 GMT
Thank you biggles3 for both sets of the datasheet files! I've created 2 PDF's from them, and have added links for the 25mm 1.4 and 18mm 2.8 lenses into the spreadsheet in a new 'Prototype' section. I think I've deciphered enough of the text to pull out a few spec details, but I have no idea if I've succeeded. If anyone fluent in German could take a look at the PDF datasheets and confirm my guesses, it would be greatly appreciated. Excuse the lower quality diagrams for now. I plan on reworking them to larger sizes and a better quality when time permits. bobblehat ... After looking at all the details in that link, I ran a search on the US Patent number given, and found the massive 50 page USPO submission that went along with the article. All I can say, is WOW. These lenses deserved to be made, and it's unfortunate they never got to see production. |
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on Nov 2, 2019 17:12:37 GMT
Posted: Nov 2, 2019 17:12:37 GMT
Curiosity made me do it. :) A quick mockup of the 25 1.4...  |
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on Aug 12, 2021 10:46:32 GMT
Posted: Aug 12, 2021 10:46:32 GMT
Hello again lumiworx,
Just for information, it's worth noting that the Zeiss 25mm f2.8 had 3 iterations; in addition to the final MM type, there were two different AE versions as those with early serial numbers were something of a failure being deemed far too soft. Zeiss received a number of complaints and quietly revised the lens - though it never recalled the first batches and did not publicise the changes - continuing to sell it as though nothing had ever happened. So, if you ever see an AE lens for sale, go for a late serial number or simply wait for a MM version. Hello, what are those early numbers of the 25mm that are soft? My copy's #90343277. |
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on Aug 12, 2021 16:40:22 GMT
Posted: Aug 12, 2021 16:40:22 GMT
Hello again lumiworx,
Just for information, it's worth noting that the Zeiss 25mm f2.8 had 3 iterations; in addition to the final MM type, there were two different AE versions as those with early serial numbers were something of a failure being deemed far too soft. Zeiss received a number of complaints and quietly revised the lens - though it never recalled the first batches and did not publicise the changes - continuing to sell it as though nothing had ever happened. So, if you ever see an AE lens for sale, go for a late serial number or simply wait for a MM version. Hello, what are those early numbers of the 25mm that are soft? My copy's #90343277. Welcome to the Forum corlius I think you may be trying to compare apples with pears. I don't think the serial number you quote is for a Contax Zeiss 25mm lens as it has too many numerals and should not start with a 9. Are you referring to a more modern lens intended for a different camera system? Of course, I stand ready to be corrected... To answer the general question, the early AE version starts with 58xxxxx and the corrected ones start somewhere around 60xxxxx but any lens starting with 61xxxxx or higher should be fine. |
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on Aug 12, 2021 19:15:20 GMT
Posted: Aug 12, 2021 19:15:20 GMT
A quick look on a few ebay listings suggests it's from the much later ZE/ZF models, and not a Contax/Yashica C/Y mount version, so the 'soft numbers' wouldn't apply. For sale on ebay.... A Nikon F-Mount 28,2.8 ZF model, and Canon Mount ZE both have a serial #'s starting with 15. Both contain 8 numerals in total on serials, so that matches the count you have and not the 7 digits on C/Y mount lenses. |
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