C to M12 mount adapter

[Radius8]

Since I was so impressed with the Mobius platform as a dash cam, I bought one to use at work as a general mini camera to record scientific experiment. Unfortunately, the standard lens offerings were rather limiting.

I discovered that someone makes an adapter so that I could use a C-mount lens on the Mobius:
https://www.amazon.com/gp/B01E536ZZ6
This seems to work for a standard C-mount CCTV lens we had laying around. Unfortunately, the CS-mount lenses could not be focused even with the adapter screwed all the way in . The CS lens need to be at 12.5 mm from the sensor vs 17.5 mm for the C.


BTW, this compact and free little utility called Webcam Viewer is nice for those on the PC for focusing the Mobius:
https://bustatech.com/webcam-viewer-v3-5-released/

 

[Lola]

@Radius8 Couldn't you use a shorter Mobius sensor mount (shorter barrel), allowing it it get closer. Unless there is something I am misinterpreting, this should work.

 

[Radius8]

@Radius8 Couldn't you use a shorter Mobius sensor mount (shorter barrel), allowing it it get closer. Unless there is something I am misinterpreting, this should work.

Yes, I was thinking that as well. I see that M12Lenses.com offer a shorter mount (10 mm) that has the correct screw hole spacing and may give me a few more mm to work with. That being said, the Mobius case will need to be hacked off in the front. That is my next thing to try.

If this works, that will open more lens options since there are lots of choices for CS mount.

 

[Dashmellow]

The risk with mounting a CS lens on a Mobius, especially if you go with the shorter threaded barrel is that it puts a great deal of stress on the mount as well as the sensor plate which risks focus problems or damage to the module. When I installed a 2.8 to 12mm CCTV varifical lens on a Mobius this past summer I replaced the stock threaded lens holder with a beefier one because even that lens put additional stress on the module because it was quite heavy and not well supported. If you can achieve the proper back focus for your CS lens and get this to work you may need to come up with a way to support the lens in some way too. Maybe a small cheese plate with a lens cradle support for both the camera and lens would be a good option?

http://www.smallrig.com/smallrig-mounting-cheese-plate-1598.html



Some time ago a DCT member installed an alternative mount on a G1W allowing for the use of various 35mm and CS lenses. You might find that thread interesting.

 

[Lola]

The risk with mounting a CS lens on a Mobius, especially if you go with the shorter threaded barrel is that it puts a great deal of stress on the mount as well as the sensor plate which risks focus problems or damage to the module. When I installed a 2.8 to 12mm CCTV varifical lens on a Mobius this past summer I replaced the stock threaded lens holder with a beefier one because even that lens put additional stress on the module because it was quite heavy and not well supported. If you can achieve the proper back focus for your CS lens and get this to work you may need to come up with a way to support the lens in some way too. Maybe a small cheese plate with a lens cradle support for both the camera and lens would be a good option?


http://www.smallrig.com/smallrig-mounting-cheese-plate-1598.html

View attachment 35172 View attachment 35171

Some time ago a DCT member installed an alternative mount on a G1W allowing for the use of various 35mm and CS lenses. You might find that thread interesting.

.

 

[Lola]

I wrote a reply but it seems to have disappeared when I clicked on post reply. No idea what happened. I see it left the period in!

Anyway, I should have thought about the larger weight and length of the CS lens. Dashmellow's idea is definitely valid and Radius8 should give that some thought.
It wouldn't hurt to also leave some room for a lens lock ring where the lens comes out of the camera body, this would help some by giving support at the lens/camera neck area. I like the idea of the CS lens but I hope Radius8 you are aware of the cost of these lenses.

 

[Radius8]

Thanks both. Yes, I did think about the weight of the larger lenses. That being said, I though that I should get the thing working first before investing all this time and material into making a mount .
As far as using a locking ring, I don't thing there is space. I had to screw the adapter ring all the way in as it is in order to get the C lens sufficiently close to even focus. That's why the picture in my original post shows the unassembled mobius (could not get the mount/sensor assembly to fit without trimming the case).

@Dashmellow, I did acquire the telephoto lens you reviewed (at least one that looks like it) and I had to trim the case to make it fit. But it works fine. I added some thick tape as shims in the case and it seem to "clamp" the stock mount pretty securely once the case is re-assembled.

@Lola, there are some CS lens that are roughly the same cost as the M12 ones. Sure, the "good" ones can be more than the Mobius. The options are more though and potentially, one that allows variable iris can be beneficial for day/nigh use. Size wise, some of the fixed iris are actually smaller than the mentioned telephoto.

Still worth the effort, not necessarily for Dashcam use but as Dashemellow commented in other posts, the Mobius is a fantastic platform, great form factor and a great value. I ran the thing for days at 4 degree C , recording a scientific experiment. I even ran it inside a pressure chamber (for a short time) at 1.8 atmosphere at -5 C and subjected it to rapid de-presurization to ambient. The thing still works.

The possibilities are endless. May be someone can mount Mobius to their pet and see where they go.