C lens going out of focus?

if only they had lens that is better than this one
i got a replacement and its got even more problems :(

That's what I'm worried about too but I guess I'll just have to wait and see how good or bad the replacement module will turn out to be. At least with the Mobius it's easy to swap in a different lens module rather than end up with a useless camera.
 
I put my C lens in the module of my first Mobius (A lens). The images look great and even with outside temperatures of 29 Celsius degrees there was no focus shifting (in 2 hours recording) as with the original module (first iteration of FRP modules).
Screwing the C lens was very easy all the way, but I felt there is a little movement when I tighten the screw to keep it in place.
Screwing the A lens in the FRP module was pretty difficult from the begining and I didn't manage to turn it enough by hand to get a decent focus, so I gave up for the moment.
Also I noticed that the A lens had some sticky grease at the end of the barel, while the C lens didn't. Looks like it's for higher friction, in order not to turn too freely when you adjust the focus.
 
OK so I finally had a chance to do a camera to camera compare with my A lens camera and my C lens camera.
Disclaimer - The pictures below are highly marred by the defroster lines and reflections from my rear deck.

Here is my Mobius A lens in wide mode:
Frame%25202015.05.07%252013-53-33%2520%25280-07-30.021%2529.jpg


Here is my Mobius C lens in narrow mode:
Frame%25202015.05.07%252013-31-10%2520%25280-13-59.940%2529.jpg


First I noticed that my A lens Mobius has had it's time drift a bit. I also thought it was weird how the C lens was affected by my 15% tint in the bottom corners of the windshield.
 
I put my C lens in the module of my first Mobius (A lens). The images look great and even with outside temperatures of 29 Celsius degrees there was no focus shifting (in 2 hours recording) as with the original module (first iteration of FRP modules).
Screwing the C lens was very easy all the way, but I felt there is a little movement when I tighten the screw to keep it in place.
Screwing the A lens in the FRP module was pretty difficult from the begining and I didn't manage to turn it enough by hand to get a decent focus, so I gave up for the moment.
Also I noticed that the A lens had some sticky grease at the end of the barel, while the C lens didn't. Looks like it's for higher friction, in order not to turn too freely when you adjust the focus.

I've been thinking of doing just you've done. ie buying just a C lens only and replace the A len. Keeping the A lens module.
Do you have to set the GUI setup to C lens?
Is night shot improved like C lens?
Does the C lens "little movement" affect set focus?
Thanks.
 
Only the actual lens optics matters in settings, so yes, in the GUI is set up to C. Actually, during a DIY session I manage to cut the ribon of the A lens module... it saved my finger, so my setup is now like this:
- ribon, metalic plate and sensor - from the Mobius C (with heat related focus shifting)
- metalic lens module - from my 2013 Mobius A
- C lens barrel - from the Mobius C
In the meantime I manage to adjust the focus, the problem was that I was tightening the screw to much. Now I'm happy about the result, this lens is in my front camera and the recordings look good. I don't have night footage as summer is already here (at least regarding the daylight), but from initial tests it shouldn't be any problems.
 
Thanks HoraceCJ. I'll be doing what you've done.
 
What's the best way to go about initially focusing this? Webcam mode looks to be a much lower resolution than 1080p, and I can't really get any sharpness at all out of it.
 
We
What's the best way to go about initially focusing this? Webcam mode looks to be a much lower resolution than 1080p, and I can't really get any sharpness at all out of it.

The Mobius should provide at least 720p in web cam mode with should provide plenty of sharpness to focus the camera. On a Mac, 720p will be the default resolution in Quick Time player. On Windows or Linux it will be dependent on which web cam software you are using.
 
Last edited:
Does anyone know if the free focus problem C lens batch is released on market ? If the answer is Yes, how can it be identified ? Thank you!
 
I've spent a few weeks with the Mobius (C lens) now, it's a great DIY project. Power is tapped from the rearview mirror into a DC converter cannibalised from a USB cigar adapter built into a small black box (35x35mm from Maplin) which is stuck to the front of the rearview mirror. The Mobius itself is attached with Velcro to the bottom of the plastic housing which covers the sensors on the windscreen (Mazda 6 2014). I had to solve a few challenges on the way but it works pretty well now.

Perhaps the last remaining issue is the focus changing with heat. The 20x20mm heatsink has probably helped a touch although I couldn't systematically test it. I have the latest C lens with a connector on both ends of the ribbon cable. I've waited for this new lens because I thought the thicker back plate of the lens would remove the focus problems but on repeated reads of the forum it seems that the plastic lens base expanding with heat is the culprit.

Once there is a hot weekend and I can get repeated shots of the same scene at increasing temperatures, I will have a few options. Contacting the seller (Webbex) with the images and see if they can offer a solution, or improving the cooling which takes me to the question:

Have people tried fitting a small cooling fan on a heatsink stuck on the Mobius' aluminium heatsink? Does it help with the focus problems, or would the heating of the lens not be affected? I have a 5V 17x17mm fan which would sit nicely on the heatsink. Wiring it to the capacitor's connector would be easiest but that's not workable as the fan would drain the capacitor after power is cut. The only option is to take power for the fan from the DC converter through a mini jack socket mounted in the plastic box and a mini jack plug on the fan's wires (so that the Mobius can be taken out of the car. Yes, another nice DIY project but wasted time if the fan doesn't help.
 
An alternative is to put the cooling fan inside the Mobius. I've checked and the 17x17mm fan would fit just fine next to the supercap (across). The fan's two thin wires can exit next to the USB socket (just) to get external 5V power. The Mobius cover has small holes in the corners and there is a gap arlound the lens so there should be some air circulation even without drilling the case. I'm not sure about effectiveness though...
 
Last edited by a moderator:
An alternative is to put the cooling fan inside the Mobius. I've checked and the 17x17mm fan would fit just fine next to the supercap (across). The fan's two thin wires can exit next to the USB socket (just) to get external 5V power. The Mobius cover has small holes in the corners and there is a gap arlound the lens so there should be some air circulation even without drilling the case. I'm not sure about effectiveness though...

The idea of installing a micro fan has been discussed on DCT a number of times but the problem with installing a fan on top of a Mobius camera is that no matter how small and quiet it may seem it will introduce noise in your videos.

To answer your question someone did experiment with your idea of installing a fan over a heat sink attached to a Mobius and turned his camera into quite an unsightly contraption that was no longer the discreet little camera he started out with. Unfortunately, the member only gave an anecdotal description of his results instead of providing any videos, noise comparisons or temperature measurements to document his results.

There is a lengthy, almost two year old thread here called The Mobius and Heat Issues you may find interesting.
 
Last edited by a moderator:
I am obviously reinventing the wheel a bit, thanks for the links. The noise of the fan is quite loud certainly when the fan is inside the Mobius, but even when it's outside about 10cm away. I think I am giving up on the fan...

My heatsink is low profile (21x21x6mm http://uk.rs-online.com/web/p/heatsinks/5040700/ the image is misleading) and does not add too much bulk so I'd be happy to live with that if it fixes the focus issue.

I've turned in the lens about 2mm (measured as the distance between the marks I have on the lens) today before we went out to do the shopping on a decent sunny day, about 20C. When starting off it was badly out of focus but in about 15 minutes driving it got better. This overcorrection of the focus may be a way to find a setting which gives sharp focus when hot but clearly this is not ideal as using it cold (or on a cycle helmet mount) it would be out of focus.

Next I'm trying to get a controlled recording in the warm stationary car and see what Webbex say.
 
I've turned in the lens about 2mm (measured as the distance between the marks I have on the lens) today before we went out to do the shopping on a decent sunny day, about 20C. When starting off it was badly out of focus but in about 15 minutes driving it got better. This overcorrection of the focus may be a way to find a setting which gives sharp focus when hot but clearly this is not ideal as using it cold (or on a cycle helmet mount) it would be out of focus.

Next I'm trying to get a controlled recording in the warm stationary car and see what Webbex say.

I found that the focus shift was happening at lower temperatures than I thought it would. On warm days with a temperature over 30°c I wasn't noticing much change in focus, but cooler days I was.

If you can park your car somewhere that has large writing or lettering on a wall I find it makes focus issues quite easy to notice.

If Webbex sends you a new module I hope it is a good one. My replacement module seems to have focus issues :(
 
My Mobius V3 with pluggable C lens definitely has a temperature dependent focus shift. I am now thinking of an alternative dashcam and the Innovv C2 is on the top of my list. It has common roots with the Mobius, size is about the same, video quality looks excellent and I haven't seen anyone on DCT complaining about a focus shift. If someone has experience with both the Mobius and the C2, please give me some insight.
 
Has anyone tried to find a shop that could make metal lens holder? I live in a small town with limited options. If someone can get a quote it would help a lot.
 
Back
Top