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08-06-2014, 12:12 AM   #1
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How to identify C mount lenses?

Hi, I'm thinking of getting a CCTV lens to play with my Q. The problem is that CCTV lenses come in C and CS mount and it is never explicitly mentioned on the lens itself. Online CCTV lens sellers rarely state if they are selling a C or CS mount lens. To make things worse, some don't even know what they're selling. Is there any way of telling apart a C from a CS mount lens by just visual inspection?

Thanks!

08-06-2014, 12:54 AM   #2
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C ( cine 16mm film) mount is the thread 25.4mm (1 inch) in diameter , flange focal distance is 17.526mm
CS ( surveillance ) same as C mount but flange is 12.5mm
D (8mm film) diameter 15.88mm , flange 12.29mm
they are all screw type mounts
08-06-2014, 02:16 AM   #3
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they don't give out flange number on ebay. the easiest way to identify CS vs C mount is that you have a zoom with f/1.4 or larger aperture, as these guys are definitely CS-mount. Also, prime CCTV lens with focal less than 6mm "tend" with f/1.4 tend to be CS mount.
08-13-2014, 08:56 PM   #4
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If that is the case, would it be right to say most CCTV lenses are CS? I had two CCTVs with zoom lenses in my office. When I swapped their lenses, neither could focus. I suspect one is a C while the other is a CS. The mounts seem identical and there is no telling on the lenses themselves if they are C or CS. Really kind of frustrating

08-13-2014, 11:16 PM   #5
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QuoteOriginally posted by weijen Quote
If that is the case, would it be right to say most CCTV lenses are CS? I had two CCTVs with zoom lenses in my office. When I swapped their lenses, neither could focus. I suspect one is a C while the other is a CS. The mounts seem identical and there is no telling on the lenses themselves if they are C or CS. Really kind of frustrating
If neither could focus then they are CS-mount. I would say most CCTV lens of higher focal range (mostly above 8mm but then depend) are C-mount. As mentioned earlier, CS-mount len tend to have faster aperture and smaller in size.

I mount CS-mount lens on pentax Q also; just buy some pentax Q body cap, drill a hole,and give it a try as pentax Q body cap has smaller distance depth than d-to-Q mount or C-to-Q mount.

Also, those CS-mount lens of yours can focus on pentax Q if you move them closer to the pentax Q sensor, the so-called freelensing
12-07-2015, 08:28 AM   #6
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QuoteOriginally posted by rendition Quote
If neither could focus then they are CS-mount. I would say most CCTV lens of higher focal range (mostly above 8mm but then depend) are C-mount. As mentioned earlier, CS-mount len tend to have faster aperture and smaller in size.

I mount CS-mount lens on pentax Q also; just buy some pentax Q body cap, drill a hole,and give it a try as pentax Q body cap has smaller distance depth than d-to-Q mount or C-to-Q mount.

Also, those CS-mount lens of yours can focus on pentax Q if you move them closer to the pentax Q sensor, the so-called freelensing
after you drill the hole how do you keep the lens in place with some epoxyI was thinking about doing this with a lot of old lenses for my micro4thirds and sony a7 just fine body caps and drilling holes I think I would get some very similar toy camera kind of effects but sharper in the center
12-21-2015, 06:27 PM   #7
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QuoteOriginally posted by i_trax Quote
C ( cine 16mm film) mount is the thread 25.4mm (1 inch) in diameter , flange focal distance is 17.526mm
CS ( surveillance ) same as C mount but flange is 12.5mm
D (8mm film) diameter 15.88mm , flange 12.29mm
they are all screw type mounts
So a CS lens should be 5mm closer to the sensor than a C mount provides?

Wikipedia lists the Q-mount flange distance as 9.2mm, so a CS-to-Q adapter could be built in theory, but I've never seen such a thing provided commercially.

I did find a supposed CS-mount lens to C-mount camera adapter, but it appears to move the lens farther from the sensor, rather than closer.
http://www.ebay.com/itm/311324205181?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Last edited by reh321; 12-21-2015 at 06:38 PM. Reason: info about adapter
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