Free CCTV lens

[Calzone]

Hello,

I'm a film guy who is way out of his element, but earlier today a friend gave me this CCTV lens that I assume is a C-mount. It is a Cosmicar/Pentax 8-48mm zoom lens with a F-22 to F1.0 range.

It also has a E55 B&W filter on it that says "NL 3", but also a yellow filter without a ring sandwiched in between the B&W filter and the front element. BTW the B&W NL 3 is not flat and displays a convex front.

Any help in educating me as far as equiv. FOV range in 35mm?

Also Although 1:1.0 is clearly marked on the lens barrel the there are two signified F-stops for wide open: 1.0<W; and 1.2<T. Any idea what this means?

Last question is on a Nex-7 at what focal length does vignetting become evident with CCTV lenses with C-mount?

Thanks in advance.

I'm hoping I effectively found a Noctilux zoom that will work well on a Nex-7

Cal

 

[chrishayton]

Its F1.0 at the wide end and 1.2 at the tele lens (hence the W and T)
Vignetting will probably be there all the time. 25mm lenses produce a circular image. theres some 35mm lenses that cover APS with a bit of vignetting. I wouldn't hold much hope for it being very usable but it may be ok on the long end.

 

[Calzone]

Its F1.0 at the wide end and 1.2 at the tele lens (hence the W and T)
Vignetting will probably be there all the time. 25mm lenses produce a circular image. theres some 35mm lenses that cover APS with a bit of vignetting. I wouldn't hold much hope for it being very usable but it may be ok on the long end.

Thanks. What you say makes lots of sense. On the long side any idea what 48mm and 35mm might translate into 35mm equivilents?

Like I said I'm clueless.

Thanks again.

Cal

 

[raid]

Same brand lens but 25mm/1.4; on Olympus EP-2:

 

[Calzone]

Same brand lens but 25mm/1.4:

WOW. Thanks for the post. My mind is racing.

Cal

P.S. My lens only close focuses to 4 feet. I suspect that the B&W LN 3 is a close up lens. My friend and I work at a research hospital. Perhaps this was used to record surgeries.

I also assume the yellow filter that was sandwiched inbetween was added for increased contrast.

 

[Particular]

Cal, I think there are a few different sensor sizes for security cameras, so the 35 equivalents will vary. I think somewhere between 10mm and 15mm will be a standard lens. It is most likely a CS-mount, which is C-mount thread, but with a different mount to sensor distance. People use these lenses on micro 4/3, but they all seem to vignette quite badly. Perhaps these can be made to work on those new Nikon or Pentax cameras. I would't expect too much in terms of image quality.

 

[raid]

With focal length>24mm, there is no vignetting on a micro 4/3 camera. My lens cost $35 shipped (new) from ebay. The perspective is 50mm on the EP-2, with added depth of field.

 

[Calzone]

Cal, I think there are a few different sensor sizes for security cameras, so the 35 equivalents will vary. I think somewhere between 10mm and 15mm will be a standard lens. It is most likely a CS-mount, which is C-mount thread, but with a different mount to sensor distance. People use these lenses on micro 4/3, but they all seem to vignette quite badly. Perhaps these can be made to work on those new Nikon or Pentax cameras. I would't expect too much in terms of image quality.

Cristian,

Thanks. Its still fun doing the forensics. I see a 1 inch diameter thread like on the Bolex I had. How to know if its CS-mount? Anyways I'll give it to Tung at the next meet-up since he has a Nex-7.

Cal

 

[emmef2]

Nice rendition of the 25mm Cosmicar, I am eyeing that lens since a few weeks for my E-PL2, does it vignette a lot at longer focus distances?

 

[ithrowbuckets]

It'll probably vignette something bad. 25mm is about the limit for M4/3 for no vignette, you'll probably get it through the whole zoom range