Old Mobius 1 A2 lens out of focus even at most extreme rotation

[dchang0]

Hi, everyone--

I've been a happy owner of a Mobius 1 bought years ago on this forum's enthusiasm about it.

Over time, probably due to the hot desert climate, the focus has gone further and further out such that it's blurry all the time, whether cooled down or heated up.

I bought a 0.9mm hex wrench (lost the original) and loosened the grub screw on the A2 lens module but found that the lens is already turned to the extreme shortest focal length. Turning even a quarter turn in the other direction (lengthening the focal length) only makes it even more blurry.

So, I am kinda stuck. I suspect that either the lens, the module housing, or the sensor has permanently failed somehow.

There are these three options:

1) Buy a complete, new A2 lens module with new lens, new sensor, new module housing. Most expensive option at $27, but I will likely get a working camera. I can also use it to diagnose exactly which part failed in the original module. The downside is that I can put that $27 towards a brand new dashcam that has far more features and better specs such as a Viofo T130.

2) Buy a new lens only. I can try some of the interesting lenses mentioned in this forum, some as low as $8. If it turns out that the sensor and module housing are fine, this will get me a working camera and probably one that works better than the original A2 lens.

3) Take apart the lens module and sand down the module housing (made of plastic) to allow me to shorten the focal length a bit more. This is by far the cheapest option but if I screw up it could be bad. Ways to screw up include: sanding the back such that it is no longer perpendicular, shortening the housing such that the lens impacts the sensor, etc.

I'm wondering: which of the three parts is the one most likely to have failed? I'm thinking the sensor went bad since it is the one that heats up the most and would experience the most thermal expansion and contraction repeatedly over time. If the sensor went bad, then option 2 is almost certainly not going to work, and option 3 might work but probably won't.

Thanks in advance for any help/advice!!

---

As a side note, I also had the original battery expand up like a balloon and split the case open. I can close it back up mostly but will probably have to replace it since the snap tabs at the rear broke off.

Also, I ended up making my own supercapacitor pack using two Eaton 2.7V 6F supercapacitors bought over at Digikey. They work great. I transferred over the tiny power cable from the battery to the supercapacitors soldered in series. Total cost was $6.72 for the two supercapacitors. Hopefully this will help anyone who is looking for the now-hard-to-find supercapacitor packs.

 

[kamkar]

Welcome to the forum dchang0

I was not aware this lens version was that close to its inner max, that kind of suck if that is a norm for that particular model, if it is the top of the lens that hit its mount, as you say you might be able to take a little off the top.
Mind you as these are fine thread, it might be hard to get the lens to go in´to the thread correctly, you probably also need to ream the end a little to pull it off.

getting an new set of housing plastics ASO should not be a problem.

As the out of focus seem to be permanent you should be able to refocus in if you can get the lens to screw to the sweet spot, i have tried the same with a dashcam in 2012 or there about, once adjusted it worked just fine ever since, or at least for a year or so more before that camera got replaced by a newer model.

 

[dchang0]

Welcome to the forum dchang0

I was not aware this lens version was that close to its inner max, that kind of suck if that is a norm for that particular model, if it is the top of the lens that hit its mount, as you say you might be able to take a little off the top.
Mind you as these are fine thread, it might be hard to get the lens to go in´to the thread correctly, you probably also need to ream the end a little to pull it off.

getting an new set of housing plastics ASO should not be a problem.

As the out of focus seem to be permanent you should be able to refocus in if you can get the lens to screw to the sweet spot, i have tried the same with a dashcam in 2012 or there about, once adjusted it worked just fine ever since, or at least for a year or so more before that camera got replaced by a newer model.

Thanks for the kind welcome, kamkar!

It apparently shipped from the factory with the lens screwed as far in as possible (I did not ever change the focus or even loosen the grub screw in all these years). In the past, it was always acceptable for the focus--it wasn't great but wasn't bad either. I could read license plates clearly about one car length away. Now, it can't even do that...

I'm wondering if the sensor or the lens got delaminated or perhaps the IR filter stuck to the back of the lens is damaged somehow.

I'll definitely take care to protect the threads if I decide to sand or file the housing shorter from the front.

 

[TonyM]

Is the lens definitely hitting a hard limit, or is it just glued threads that are stopping the lens from going in any further?

 

[dchang0]

Is the lens definitely hitting a hard limit, or is it just glued threads that are stopping the lens from going in any further?

It's definitely hitting a hard limit. It's screwed all the way into the plastic lens housing such that the rear edge of the wide part of the lens is flush against the front edge of the threaded portion of the housing.

 

[dchang0]

I'm beginning to think the failure is inside the lens.

1) It's not likely to be the plastic lens housing, because that should expand when heated and then contract to roughly the original size when cooled to room temperature. It shouldn't permanently expand to a longer length. And I'm sure the lens hasn't skipped threads; it is screwed down flush against the housing's front edge.

2) It seems that CMOS sensors can handle very high heat up to 70 to 85 degrees Celsius, much hotter than the temps inside most vehicles even in the hot desert sun. I took a look at the sensor on its PCB and it doesn't look like it came loose from the PCB.

That seems to only leave the lens's internals or perhaps the IR filter failing permanently due to the heat.

Has anyone seen lens units (regardless of camera) fail due to heat? I've found a short discussion online about this in some other brand of camera, but I can't tell if they're talking only about the lens or about the entire lens module (including lens, housing and sensor).

 

[TonyM]

There are two types of Mobius lens holder. A long one with a grub screw, and a short one without the screw. You could try getting hold of the shorter one from a reseller.

 

[dchang0]

There are two types of Mobius lens holder. A long one with a grub screw, and a short one without the screw. You could try getting hold of the shorter one from a reseller.

Hey, that's a great idea--I had no idea that they are different lengths.

Mine is the plastic one with the grub screw, not the aluminum one with the grub screw and not the later plastic one with the glue.

I have seen generic plastic lens holders for dirt cheap (10 units for $8) on Amazon, but I'd have to compare the dimensions to see if they are a match. I'd love to find an aluminum one with a shorter length and a grub screw.

Thanks for the tip!

 

[TonyM]

I'm beginning to think the failure is inside the lens.

1) It's not likely to be the plastic lens housing, because that should expand when heated and then contract to roughly the original size when cooled to room temperature. It shouldn't permanently expand to a longer length. And I'm sure the lens hasn't skipped threads; it is screwed down flush against the housing's front edge.

2) It seems that CMOS sensors can handle very high heat up to 70 to 85 degrees Celsius, much hotter than the temps inside most vehicles even in the hot desert sun. I took a look at the sensor on its PCB and it doesn't look like it came loose from the PCB.

The board that the sensor is mounted on can become distorted if it gets too hot. It doesn't take much for the focus to shift.

That seems to only leave the lens's internals or perhaps the IR filter failing permanently due to the heat.

The IR filter is completely flat, so it should have no effect on the focus.

Has anyone seen lens units (regardless of camera) fail due to heat? I've found a short discussion online about this in some other brand of camera, but I can't tell if they're talking only about the lens or about the entire lens module (including lens, housing and sensor).

I've seen and read about various dashcams suffering from focus shift. Sometimes it is temporary, in other cases correct focus does not return when the camera cools down.

 

[TonyM]

Hey, that's a great idea--I had no idea that they are different lengths.

Mine is the plastic one with the grub screw, not the aluminum one with the grub screw and not the later plastic one with the glue.

I have seen generic plastic lens holders for dirt cheap (10 units for $8) on Amazon, but I'd have to compare the dimensions to see if they are a match. I'd love to find an aluminum one with a shorter length and a grub screw.

Thanks for the tip!

I don't think any of the generic ones work because the distance between the screws is wrong. I have one spare here but doubt it is cost effective to post it to you!

 

[dchang0]

The board that the sensor is mounted on can become distorted if it gets too hot. It doesn't take much for the focus to shift.


The IR filter is completely flat, so it should have no effect on the focus.


I've seen and read about various dashcams suffering from focus shift. Sometimes it is temporary, in other cases correct focus does not return when the camera cools down.

Uh oh, I sure hope it's not the sensor board. If it is, I'm basically stuck with buying a whole new lens module, which means I might as well put the money towards a newer dashcam.

Thank you for the explanations!

 

[dchang0]

I don't think any of the generic ones work because the distance between the screws is wrong. I have one spare here but doubt it is cost effective to post it to you!

Thanks very much--you're right, the postage cost will be too high.

I haven't measured the screw spacing of the lens holder in my Mobius, but the generics on Amazon say they have a 20mm screw spacing. That seems too wide to me to match the original, but I'll double check with some calipers.

I figure my best option at this time is to buy or borrow a low-cost but acceptable generic M12 lens and try it out. A varifocal lens with a wide focal length range could be used to prove whether the sensor has failed or not.

 

[TonyM]

If you are considering a varifocal, the 2.8-12mm should cover the range similar to your A2 lens. The good thing with a varifocal is you can easily refocus without opening up the camera.

The 'long' lens holders are better suited to the varifocal lens than the short type.

 

[SawMaster]

@dchang0 Many thanks for the supercap source Can you confirm it is THIS ONE?

Phil

 

[dchang0]

@dchang0 Many thanks for the supercap source Can you confirm it is THIS ONE?

Phil

Yes, it is exactly that one. P/N 283-4204-ND at Digikey. They are 8mm in diameter and thus are very easy to fit in the case vertically. The caps are long but will just barely fit inside the case to the left of the lens module (above the SD card holder).

 

[dchang0]

If you are considering a varifocal, the 2.8-12mm should cover the range similar to your A2 lens. The good thing with a varifocal is you can easily refocus without opening up the camera.

The 'long' lens holders are better suited to the varifocal lens than the short type.

Perfect--thanks very much for your help!

 

[dchang0]

I just measured the lens housing, and it appears to have 18mm screw spacing, so the generics with 20mm hole spacing will not work.
The housing itself measures 15mm wide at the rectangular base (without the screw ears) and 12.5mm from front (round end, where lens screws in) to back (rectangular end, where sensor PCB is attached).
With the screw ears, the base measures about 21.9mm wide. The rectangular base measures 4.2mm tall along the center axis and the round tube measures 8.3mm tall along the center axis.

 

[dchang0]

Looking at photos of brand new A2 lens modules, it seems they all ship with the lens fully screwed into the housing, just like mine was and still is. That seems unusual--wouldn't it be better to ship it with a shorter lens housing or with the lens only partially-screwed in so that there's the possibility of further adjustment in both directions? Is this something the mfg. addressed by shipping future units with a shorter lens holder?

 

[Dashmellow]

Looking at photos of brand new A2 lens modules, it seems they all ship with the lens fully screwed into the housing, just like mine was and still is. That seems unusual--wouldn't it be better to ship it with a shorter lens housing or with the lens only partially-screwed in so that there's the possibility of further adjustment in both directions? Is this something the mfg. addressed by shipping future units with a shorter lens holder?

I can see what you are talking about. Assuming the new lens is in good focus you should be ok with it. Another option might be to consider the C2 lens if you are ok with the wider coverage. The C2 lens is an excellent optic.

 

[dchang0]

I can see what you are talking about. Assuming the new lens is in good focus you should be ok with it. Another option might be to consider the C2 lens if you are ok with the wider coverage. The C2 lens is an excellent optic.

Hmm, I think I'll go with a new C2 module instead, then. I don't want to repeat what I went through with my A2 where it arrived okay but a couple of years later went out of focus. Who knows if we will be able to buy parts 2-3 years from now?

Thanks for the C2 recommendation!