What is this 25-100mm f/1.8 screw-mount lens, and what mount does it use?
Asked 10/5/2017
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I’m trying to identify an unbranded vintage zoom lens marked “lens made in Japan” and “No. 105022” on the mounting flange. It appears to be a 25-100mm f/1.8 lens with a screw mount that I measured at about 24mm across, though it may be close to 1 inch. The lens has an older black-and-silver “zebra” style finish and two zoom/focus barrels. What brand/model is it likely to be, and what mount/system was it made for?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
8y ago
2 Answers
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This appears to be a C-mount lens, probably for video cameras, such as for 8mm or 16mm video. From the information given, there is no way to tell what the intended camera format was.
Based on the alternating silver/black pattern on the focus, aperture, and zoom rings, this appears to an older Tamron lens. A couple images from a lens that looks like it matches its exact appearance shows up in Google, referring to a Yahoo auction page that no longer exists, but was titled "not for sale TAMRON TV ZOOM f=25-100mm 1:1.8 C mount lens".
Tamron TV zoom 25-100mm ƒ/1.8 C-mount lens. Retrieved from Google Image cache under fair use for educational purposes
The C-mount has a 1-inch (25.4mm) diameter. As noted in the C-mount Wikipedia article linked above, just knowing that the lens is C-mount does not tell you a lot. It doesn't tell you what the lens was intended to be mounted on. Depending on the size of the image circle cast by the lens, it might be incompatible with larger (at the time) format video. For instance, if the lens was intended to be used with 8mm video, then its image circle will visibly crop if mounted on a 16mm format camera. See the following article for a similar question about lenses on different sized imaging sensors: When do the differences between APS-C and full frame sensors matter, and why?
Originally by user11924. Source · Licensed CC BY-SA 4.0
user11924
8y ago
0
Generated from our catalog & community — verify before relying on it.
Based on the styling and markings, it is most likely a vintage Tamron TV Zoom 25-100mm f/1.8 in C-mount.
The key clue is the mount: C-mount lenses use a 1-inch diameter thread (25.4mm), so a rough measurement can easily come out a little under that. These lenses were commonly made for cine/video cameras rather than still cameras, especially 8mm, 16mm, and industrial/TV applications.
The black-and-silver “zebra” pattern also matches older Tamron designs, and community references point to a matching lens described as a “Tamron TV Zoom f=25-100mm 1:1.8 C-mount lens.”
What’s less certain is the exact image format it was designed to cover. It likely covers small cine/video formats and may cover around 1-inch-class sensors, but that depends on the specific lens version. On modern cameras, it would generally be used only with suitable C-mount adapters and may not cover larger sensors fully.
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