Mobius Telephoto Dashcam

Lola

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It's a bummer that Bangood sent the 2MP lens instead of the 3MP but in all likelihood I think you won't notice any significant difference in the results.

It's also unfortunate that Banggood is so vague and unreliable about which lens they actually ship out. Many people, including me received the 3MP lens regardless of which one they order so it seemed like that would be the case going forward. Now it seems they just ship out whichever one they happen to have in stock. I was aware that you can buy these varifocal lenses from many other sources but I wish I had known at the time I bought mine that they are widely available at such very low prices from other sources than Banggood, including many variants. These varifocals are primarily used in CCTV cameras (which is why they don't include IR-cut filters) and that's why they are so common. In fact, recently when I tore down an old vandal dome type CCTV camera I've had kicking around I found an almost identical varifocal lens inside, except that it was 2.8-10mm with a smaller maximum aperture.

If anyone is interested in buying one of these M12 Varifocals at a good price it looks AliExpress is the place to go. Dozens of vendors, including Treeye sell them.

https://www.aliexpress.com/wholesal...1223104149&SearchText=2.8-12mm+varifocal+lens


As for mounting the IR-cut filter, the ones I ordered are 9.5mm in diameter and therefore too small to be mounted on the rear of the threaded tube at the back of the lens barrel. I do plan to see if I can mount the IR filter directly behind the recessed rear optical element of the lens on the lip deep inside the tube. Mounting the IR-cut filter close to the rear element avoids any internal reflections inside the lens barrel. If you mount the filter at the back of the lens barrel tube recessed 6mm away from the rear lens element, there is a risk that light traveling through the lens may bounce off the IR filter back towards the lens and cause a loss of image contrast. You could certainly try it though, it won't hurt anything and it might work OK. Experimentation is one of the fun and educational things about DIY. :)
What you said made good sense also, I never considered the internal reflection situation, that's a really good point to consider, Does the 9.5mm filter fit a little loose when you drop it down the barrel to the lens element? Reason for asking, wondering if a 10mm would go down the barrel with out any hangups?
 

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What you said made good sense also, I never considered the internal reflection situation, that's a really good point to consider, Does the 9.5mm filter fit a little loose when you drop it down the barrel to the lens element? Reason for asking, wondering if a 10mm would go down the barrel with out any hangups?

I haven't had any time to try it yet, so I don't know how the 9.5mm filters will fit. Installing an IR-cut filter on my 2.8-12mm zoom lens is kind of a back burner project at the moment as I've been having fun playing around with the Treeye lenses. When looking for IR-cut filters I didn't happen to see any 10mm ones although they are probably available somewhere.

Yeah, stray light bouncing around inside a lens barrel will cause a loss of image contrast and eliminating that is an important aspect of lens design and quality. With any alterations we make to lenses we have to be careful not to mess that up!
 
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Harsh

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With all this talk about gluing IR cut filters, thought I'd share my experience from yesterday. While unscrewing the 12mm to replace it with the new 8mm, I somehow ended up dislodging the IR cut filter. Luckily it landed on a fresh sheet of printing paper and I left it there until I found a way to fix it back onto the lens.

Guess what I used? Gel based super glue. Used a toothpick to put four tiny dots of glue on the lens's rim and stuck the filter back. Managed not to touch the surface by holding it from the edges using two fingers. No visible damage to the glass element or the IR filter, looks as if it never happened. :)
 
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With all this talk about gluing IR cut filters, thought I'd share my experience from yesterday. While unscrewing the 12mm to replace it with the new 8mm, I somehow ended up dislodging the IR cut filter. Luckily it landed on a fresh sheet of printing paper and I left it there until I found a way to fix it back onto the lens.

Guess what I used? Gel based super glue. Used a toothpick to put four tiny dots of glue on the lens's rim and stuck the filter back. Managed not to touch the surface by holding it from the edges using two fingers. No visible damage to the glass element or the IR filter, looks as if it never happened. :)
I thought the vapours given off by that kind of glue were detrimental to sensitive lens coatings?
 

Harsh

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I thought the vapours given off by that kind of glue were detrimental to sensitive lens coatings?

Yeah I thought so too and still do. Due to the lack of a viable solution that I know off, tried it knowing the risks involved.

I think there weren't any ill affects due to the quantity used. Could've been a different result if I'd smeared the entire rim.
 

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Off-gassing from super-glue can continue for as long as a day so check closely later. It's worst when the vapors cannot escape which with 4 'dots' instead of a complete 'ring' they might be able to do- hope you get lucky (y)

Phil
 

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With all this talk about gluing IR cut filters, thought I'd share my experience from yesterday. While unscrewing the 12mm to replace it with the new 8mm, I somehow ended up dislodging the IR cut filter. Luckily it landed on a fresh sheet of printing paper and I left it there until I found a way to fix it back onto the lens.

Guess what I used? Gel based super glue. Used a toothpick to put four tiny dots of glue on the lens's rim and stuck the filter back. Managed not to touch the surface by holding it from the edges using two fingers. No visible damage to the glass element or the IR filter, looks as if it never happened. :)

I did that once several years ago and got away with it (barely) but I wouldn't try it again. You were taking a huge risk of ruining both the lens and the filter.
 

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With all this talk about gluing IR cut filters, thought I'd share my experience from yesterday. While unscrewing the 12mm to replace it with the new 8mm, I somehow ended up dislodging the IR cut filter. Luckily it landed on a fresh sheet of printing paper and I left it there until I found a way to fix it back onto the lens.

Guess what I used? Gel based super glue. Used a toothpick to put four tiny dots of glue on the lens's rim and stuck the filter back. Managed not to touch the surface by holding it from the edges using two fingers. No visible damage to the glass element or the IR filter, looks as if it never happened. :)

Used that when I was making my first DIY CPL and the fumes clouded the CPL. I did use 4 drops instead of just toothpick dip.:ROFLMAO:
 

Harsh

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Off-gassing from super-glue can continue for as long as a day so check closely later. It's worst when the vapors cannot escape which with 4 'dots' instead of a complete 'ring' they might be able to do- hope you get lucky (y)

Phil

I think it's gassed all it had to, had left it out in the sun for 30 minutes as well.

I did that once several years ago and got away with it (barely) but I wouldn't try it again. You were taking a huge risk of ruining both the lens and the filter.

Didn't really have a choice or actually cared, it's the 12mm f/1.8 that's going into the box anyway.
 

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Speaking of IR-cut filters a couple of days ago I received the new 4mm ƒ/1.2 and 6mm ƒ/1.2 lenses from Treeye to replace the ones they sent without the IR filters. I'm really impressed with how well they handled the problem, how responsive they were and how nice they've been. Anyone who is considering ordering from them should do so with confidence.
 

Harsh

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Speaking of IR-cut filters a couple of days ago I received the new 4mm ƒ/1.2 and 6mm ƒ/1.2 lenses from Treeye to replace the ones they sent without the IR filters. I'm really impressed with how well they handled the problem, how responsive they were and how nice they've been. Anyone who is considering ordering from them should do so with confidence.

I concur, 3 different orders received exactly as described. And very prompt with their responses.
 
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D

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I got my 16mm lens Scope Cam from BuyMobius today and I'm astonished at the quality. It's incredibly sharp and somehow the smaller field of view seems to dramatically reduce compression artifacts when driving. Here's a demo video I made today as a 0.25 second interval timelapse which comes out to 1.8mbps. At the start I thought the camera was aimed straight forward but it was aimed a little right. And then I adjusted it to intentionally point toward oncoming traffic. Note that many plates are readable 2 lanes over but not 3 lanes over, though they may be after sharpening. I'm impressed by how well it performs

Edit: BTW this is with the camera set to narrow mode IE 1920x1080 crop from center of sensor, rather than pixel binning from the whole sensor to get the image down to 1080p. I think that helps with sharpness a lot

 

Lola

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[/QUOTE]

All I could see was you apparently running stop and yield signs. It could be because of the speed of the video. Try making a normal video people can examine.
 
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All I could see was you apparently running stop and yield signs. It could be because of the speed of the video. Try making a normal video people can examine.[/QUOTE]

It's because it's 4fps, it looks like you roll through every stop. It is a normal video at a framerate that is ideal for dashcam use. There is zero need to waste storage space on 30fps
 

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All I could see was you apparently running stop and yield signs. It could be because of the speed of the video. Try making a normal video people can examine.

It's because it's 4fps, it looks like you roll through every stop. It is a normal video at a framerate that is ideal for dashcam use. There is zero need to waste storage space on 30fps[/QUOTE]

As someone who has used dash cam footage in a complicated legal matter I have to disagree with you on frame rates. At say, 40 mph you'd be amazed at how much transpires over the course of one second. Frame by frame capture at 30 fps can mean the difference between guilt or innocence.
 
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It's because it's 4fps, it looks like you roll through every stop. It is a normal video at a framerate that is ideal for dashcam use. There is zero need to waste storage space on 30fps

As someone who has used dash cam footage in a complicated legal matter I have to disagree with you on frame rates. At say, 40 mph you'd be amazed at how much transpires over the course of one second. Frame by frame capture at 30 fps can mean the difference between guilt or innocence.[/QUOTE]

That wouldn't be the purpose of a telephoto dash cam though, as it's too narrow a view to show much. The one use is to be able to capture plates and vehicles at a further distance than a wide angle lens would. For that 4fps is the sweet spot IMO. My main cameras at the front and rear are Garmin 45 units which also have GPS, speed display, and timestamp
 

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As someone who has used dash cam footage in a complicated legal matter I have to disagree with you on frame rates. At say, 40 mph you'd be amazed at how much transpires over the course of one second. Frame by frame capture at 30 fps can mean the difference between guilt or innocence.

That wouldn't be the purpose of a telephoto dash cam though, as it's too narrow a view to show much. The one use is to be able to capture plates and vehicles at a further distance than a wide angle lens would. For that 4fps is the sweet spot IMO. My main cameras at the front and rear are Garmin 45 units which also have GPS, speed display, and timestamp[/QUOTE]

I agree that telephoto lenses are quite valuable in a second dash cam and use one myself. From my experience over the last six months of experimentation and testing, I consider 16mm to be far too much magnification to be practical. The simple reason is that it will exaggerate every vibration and bump in the road and the extremely narrow FOV presents a good chance for missing something important. I would hate if I discovered after the fact that my video was slightly blurry from camera shake at the critical moment or that what I needed to capture was out of frame. At this point, I'm of the opinion that the 6mm, 8mm and 12mm lenses offer more reliably stable image capture and a more optimal FOV that still provides good license plate capture at a distance.

As far as 4 fps being some sort of "sweet spot" I'm not so sure. The more frames you capture, the more likely you are to capture key details such as plate numbers. I've often noticed that only one or two frames out of thirty will have a clear readable plate number. Personally, I wouldn't trust such mission critical evidence capture to only four frames. Jeez, I would hate to be recording at 4 fps and discover only after the fact that if only I had recorded at 30 fps I would have captured what I really needed.

One of the things I've observed in four years here on DCT is that the vast majority of members here (probably 95 % +) have never been in a situation where they actually needed to use their dash cam footage in an actual law enforcement or insurance matter and as a result many of the statements about what or what not is required of dash cam footage is speculative, theoretical and sometimes imaginary.

What's all this about saving storage space on a memory card that one would even need to shoot 4 fps? With the cost of a decent 64GB (or more) memory card these days, why not capture as much video data as possible instead of comprising yourself?
 
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That wouldn't be the purpose of a telephoto dash cam though, as it's too narrow a view to show much. The one use is to be able to capture plates and vehicles at a further distance than a wide angle lens would. For that 4fps is the sweet spot IMO. My main cameras at the front and rear are Garmin 45 units which also have GPS, speed display, and timestamp

I agree that a telephoto lenses are quite valuable in a second dash cam and use one myself. From my experience over the last six months of experimentation and testing, I consider 16mm to be far too much magnification to be practical. The simple reason is that it will exaggerate every vibration and bump in the road and the extremely narrow FOV presents a good chance for missing something important. I would hate if I discovered after the fact that my video was slightly blurry from camera shake at the critical moment or that what I needed to capture was out of frame. At this point, I'm of the opinion that the 6mm, 8mm and 12mm lenses offer more reliably stable image capture and a more optimal FOV that still provides good license plate capture at a distance.

As far as 4 fps being some sort of "sweet spot" I'm not so sure. The more frames you capture, the more likely you are to capture key details such as plate numbers. I've often noticed that only one or two frames out of thirty will have a clear readable plate number. Personally, I wouldn't trust such mission critical evidence capture to only four frames. Jeez, I would hate to be recording at 4 fps and discover only after the fact that if only I had recorded at 30 fps I would have captured what I really needed.

One of the things I've observed in four years here on DCT is that the vast majority of members here (probably 95 % +) have never been in a situation where they actually needed to use their dash cam footage in an actual law enforcement or insurance matter and as a result many of the statements about what or what not is required of dash cam footage is speculative, theoretical and sometimes imaginary.

What's all this about saving storage space on a memory card that one would even need to shoot 4 fps? With the cost of a decent 64GB (or more) memory card these days, why not capture as much video data as possible instead of comprising yourself?[/QUOTE]

The reason for the lower data rate is that you can fit more on the card. 4fps is a lot of frames, and I don't think you are much more likely to get more useful information from 30fps that doesn't involve motion. Professional grade surveillance systems are usually set to 5fps or 10fps, the recent 30fps trend in security cameras is mainly to please consumers who like "smooth video" and don't care or know that they're only getting a few days' worth of recording!

I have tried 64GB Sandisk and Samsung cards and neither worked with the Mobius. It would record a video and then crash as soon as it's stopped. So as far as I'm concerned the limit for these cameras is 32GB. Once I get a second normal angle Mobius I'll mount them on the sides and leave them running 24/7 as parking lot cameras. Sitting still, the data rate seems to be about 0.4mbps which yields 140 hours which is about 5 days

Oh yeah, another bonus of the 4fps is it uses less power because the chip has a lot less processing to do
 
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I agree that the 16mm is too narrow angle for street use, the 8mm makes more sense
 
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