M12 Lens Mount Questions

[Cubist 0]

So, recently I purchased four HIKVISION IP cameras which are great, but I'm wanting to better understand the way the lenses are on them. The camera is the DS-2CD855-EI3(EI5). I'll leave a link to the site and then another to a PDF file, but I don't think this forum allows urls, my apologies.

 

So, the camera's datasheet states that it uses an M12 lens mount. I tried to gently remove the lens from the camera but all that wound up happening was the loosening of the top most metal ring protecting the outer lens. I was hoping that the entire assembly would come loose. I would LIKE to replace the lenses on the camera with wider angle lenses. I'm wondering if anyone here has experience with changing M12 lenses on these cameras.

 

2nd question. Would a replacement lens designed for a 1/3" sensor still work with this camera's 1/2.8" sensor?

 

Thanks for any help.

 

http://www.hikvision.com/en/Products_show.asp?id=7361

 

http://www.hikvision.com/UploadFile/image/2013040714462780971.pdf

[Cubist 0]

Looks like changing m12 lenses on ip cameras is not a common thing to do. Almost 60 views. Sometimes no answer is an answer.

[EspenT 0]

this is how the lens should look when removed

 

http://www.m12lenses.com/Board-Lenses-s/12.htm

 

and this is how the part in the camera holding the lens should look like

 

http://www.m12lenses.com/M12-Lens-Holders-s/61.htm

 

Since your sensor is slightly larger you wold get a wider angle than a 1/3 with same lens. Also the corners could be darker and/or rounded.

[survtech 0]

M12 lens mounts typically have an allen head setscrew that lock the lens in position after it has been focused.

 

[MaxIcon 0]

Some lenses have a lock ring instead of the allen screw, and the Hik mini-bullets have a spot of glue on the threads holding them in place that needs to be scraped off first.

 

Most M12 lenses have an image spot large enough to cover slightly larger sensors, but M12 lenses don't have strong specs for this kind of thing, unlike older CS mount lenses. Likewise, if the new lens needs to be screwed in too far to focus, it'll hit the IR filter assembly before it's in focus. This is a common problem on replacement M12 lenses if the back focus length is too short, and few vendors specify either the BFL or the image spot size.

 

You pretty much have to order one and see if it works. If not, well, try, try again!