Mobius 1S & 8mm Telephoto Lens

TonyM

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Dash Cam
Mobius 1S Telephoto, A139, B1W
When I bought a Mobius 1S last month I also purchased an 8mm lens from AliExpress, with the intention of building this telephoto dashcam.

1673224054043.png 1673224485263.png

Mobius 1S Camera
4K Lens 12Megapixel M12 1/1.7" 8mm

I replaced the original A2 lens holder with a C2 lens holder. This is because the C2 holder is longer, and therefore more suitable for installing third party lenses, especially telephoto lenses.
I believe a C2 version of the M1S might be available in the future, but as of early Jan 2023 only the A2 version is on sale.

Full Frame : M1S, 8mm
M1S_8mm_s1.jpg

Same view on my A139 Pro 4K HDR:
A139P_s1.jpg
 
FOV & Detail Comparison : M1S 8mm vs A139 Pro 4K

Full frame, M1S 8mm
M1S_8mm_s2.jpg

Full frame, A139 Pro 4K 1600p, marked up with the FOV of the M1S 8mm
A139P_m2.jpg


Comparing both at 100%:

M1S 8mm:
M1S_8mm_c2.jpg

A139 Pro 4K:
A139P_c2.jpg
 
Mobius 1S 8mm - Early Morning

1440p30, 36Mbps, Multi-spot metering, Saturation +25, Contrast -5

 
Mobius 1S 8mm - Night

1440p30, 36Mbps, Multi-spot metering, Saturation +25, Contrast -5

 
My 2 units are on the way. Hoping the A2 holder doesn’t pose any issues.
 
My 2 units are on the way. Hoping the A2 holder doesn’t pose any issues.
The A2 in mine was a decent holder. It had a set screw. It just wasn't as long as the C2 holder.
 
DIY CPL Attempt

I removed a Viofo CPL filter from its housing and glued it directly to the front of the 8mm lens
1678661047603.png

I moved the M1S over to my thicker 3d-printed wedge so that the CPL did not hit the window
1678661151398.png

In sunny conditions, the CPL works fine if the sun is behind or to the side of the camera:
REC_001475.MP4_20230312_223707.681.jpg REC_001475.MP4_20230312_223808.621.jpg

But when the camera is facing either slightly or directly towards the sun, I am seeing rather bad flare that washes out the video:
REC_001475.MP4_20230312_223836.929.jpg REC_001475.MP4_20230312_223907.619.jpg

I wonder if removing the CPL from its holder and allowing sunlight to strike the edges is detrimental to its performance? I recall this lens suffered from flare previously, but I do not remember it being as bad as this.
 
I wonder if removing the CPL from its holder and allowing sunlight to strike the edges is detrimental to its performance? I recall this lens suffered from flare previously, but I do not remember it being as bad as this.

You could try blacking out the rim of the CPL with ink from a marker pen, or better yet a bit of black paint or black electrical tape, etc?

I'd be grateful to know if this helps, as I'm considering including a telephoto Mobius in my next dashcam setup and would like to have a viable way to incorporate a CPL.
 
DIY CPL Attempt

I removed a Viofo CPL filter from its housing and glued it directly to the front of the 8mm lens
View attachment 64457

I moved the M1S over to my thicker 3d-printed wedge so that the CPL did not hit the window
View attachment 64458

In sunny conditions, the CPL works fine if the sun is behind or to the side of the camera:
View attachment 64459 View attachment 64460

But when the camera is facing either slightly or directly towards the sun, I am seeing rather bad flare that washes out the video:
View attachment 64461 View attachment 64462

I wonder if removing the CPL from its holder and allowing sunlight to strike the edges is detrimental to its performance? I recall this lens suffered from flare previously, but I do not remember it being as bad as this.
Have you tried it without the CPL filter? Probably get better low light performance as well
 
Have you tried it without the CPL filter?
Yes, all the images and videos above were shot without the CPL.

You can see an example of lens flare without CPL in this clip from post #3 above

 
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Yes, all the images and videos above were shot without the CPL.

You can see an example of lens flare without CPL in this clip from post #3 above

How about a simple lens hood? A piece of black felt/Velcro or tape around the end of the lens ?
 
How about a simple lens hood? A piece of black felt/Velcro or tape around the end of the lens ?
For just the lens, yes this is possible. Not so easy for my DIY CPL. I can try with a different CPL that has a ring around the glass filter assembly.
 
The flare was caused by a faulty CPL. I replaced the CPL and it's been working fine ever since.
 
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