Mobius 5MP Varifocal Zoom 6-22mm ƒ/1.6

fatpanda

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I agree that it is much easier to achieve acceptable focus with this lens than most of my fixed length lenses.

I think I have found a zoom and focus setting that I am happy with for dashcam use. Close up objects are sharp, whilst ones in the distance are acceptable from my point of view.

I will probably mark those positions on the lens before I make any changes.

What would be the approx. distance you have focused on.
 
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Dashmellow

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If you read through the rest of this thread (which you may have already done by now) you'll know that we were already aware of this. :)
I did read through the thread. I must have mist that part:banghead::banghead::banghead::nurse:
 
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Dashmellow

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I agree that it is much easier to achieve acceptable focus with this lens than most of my fixed length lenses.

I think I have found a zoom and focus setting that I am happy with for dashcam use. Close up objects are sharp, whilst ones in the distance are acceptable from my point of view.

I will probably mark those positions on the lens before I make any changes.

I agree, this lens is far easier to focus for dash cam use than the 2.8-12mm ƒ/1.4 varifocal as well as some of those fixed focal length ƒ/1.2 lenses from Treeye. The increased depth off field available with this 6-22mm ƒ/1.6 lens seems to be what makes it easier to focus. Still, zoning on the precise hyper-focal distance can be a bit tricky sometimes. I too plan to place some markings on the lens barrel to indicate various zoom and corresponding focus settings.

Edit: I recall how earlier in this thread some of your images from this lens were not quite focused properly. As I said earlier today, the more you become familiar with exactly how this particualr lens performs the easier it will be to select the sweet spot that works best for you, so it appears you've found what works!
 
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TonyM

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What would be the approx. distance you have focused on.
At first I tried sitting at my desk and focusing on a particular object looking through the window, using webcam mode to observe the video on my PC screen. But when I installed the camera in the car I found that the focus was never quite right.

So I found an old phone that works with an OTG cable and the Mobius actioncam app, so I could see the video output whilst sitting in the car. I parked in a grocery store car park, behind another car and facing a wall about 20m away. I adjusted the focus until I was happy with the sharpness on both the car in front and on the wall beyond.

I would estimate that my focus distance is set at 4m or 5m, which seems rather close, although I'm happy with the results.
 

Rocketvapor

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One problem with depth of field with a dash cam is the need for low light performance, night shots.
A large aperture (low number) lens like a F1.2 to f1.6 is the worst for depth of field.
Vari-zooms might have a relatively large aperture at the wide setting, but at the tele setting is gets smaller (larger number).
Picture a restriction in the light path that is f1.2 at the wide setting, say 6mm. The iris is theoretically 5mm.
Zoom in to 22mm tele. To keep the f1.2 aperture at 22mm the iris would have to be 18mm in diameter.
While it is possible to design a zoom lens with constant aperture, the ones we use for dash/action cameras probably aren't. :)
That means the tele depth of field is improved by the iris restricting the light coming in.
One way to verify this it to take a picture and look at a histogram of the image and shutter speed at wide and tele settings.

When setting focus on a dashcam, don't try to get objects farther away than the pixel resolution allows.
In other words, why bother trying to get something 1/2 mile away nice and sharp when the pixel resolution doesn't display anything other than shapes anyway.
Focus back until distant objects are just noticeably 'unsharp'.
 
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Dashmellow

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One problem with depth of field with a dash cam is the need for low light performance, night shots.
A large aperture (low number) lens like a F1.2 to f1.6 is the worst for depth of field.
Vari-zooms might have a relatively large aperture at the wide setting, but at the tele setting is gets smaller (larger number).
Picture a restriction in the light path that is f1.2 at the wide setting, say 6mm. The iris is theoretically 5mm.
Zoom in to 22mm tele. To keep the f1.2 aperture at 22mm the iris would have to be 18mm in diameter.
While it is possible to design a zoom lens with constant aperture, the ones we use for dash/action cameras probably aren't. :)
That means the tele depth of field is improved by the iris restricting the light coming in.
One way to verify this it to take a picture and look at a histogram of the image and shutter speed at wide and tele settings.

When setting focus on a dashcam, don't try to get objects farther away than the pixel resolution allows.
In other words, why bother trying to get something 1/2 mile away nice and sharp when the pixel resolution doesn't display anything other than shapes anyway.
Focus back until distant objects are just noticeably 'unsharp'.

Yes, I talked about this a few days ago earlier in this thread. Your explanation helps further to explain it, perhaps better than I did. But, yeah, these manual varifocal CCTV lenses are fixed aperture, so the hole (aperture) will be the same size throughout the zoom range, so it gets smaller on a relative basis the more you zoom.
 
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TonyM

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I briefly tried the f1.6 6-22mm lens at maximum zoom in the car today. As I figured, it is much too extreme for dashcam use, and the depth of field is not so good as when the zoom is backed-off to about half-way as I was using previously.

This was the view of the car parked in front of me:
M1Z_0199.MOV_20180623_220635.785.jpg

I did capture the ice cream van driver having a cheeky cone whilst driving home!M1Z_0200.MOV_20180623_205703.394.jpg
 

fatpanda

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I have had this lens on my Mobius for a week now and it is fantastic. I have the zoom set about half way and I focused on a number plate about 8 meters away by putting the Mobius in webcam mode and connecting it to a laptop in my car. I am so impressed with this lens that I have ordered another for wifeys car. Thanks to Dashmellow and TonyM for the tips and instructions.
 
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Dashmellow

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I have had this lens on my Mobius for a week now and it is fantastic. I have the zoom set about half way and I focused on a number plate about 8 meters away by putting the Mobius in webcam mode and connecting it to a laptop in my car. I am so impressed with this lens that I have ordered another for wifeys car. Thanks to Dashmellow and TonyM for the tips and instructions.

Post some footage sometime! :)
 

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Not only is the maximum zoom too extreme for dash cam use but if you happen to drive on bumpy dirt roads like I do you'll experience any vibrations as dramatically magnified. You might even notice some "jello effect" from the rolling shutter in the camera.
I was getting some jello even when the car was stationary...! I also noticed that with my 24mm lens.
 

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With such impressive results, couldn't resist, ordered one too.

Been testing the new 12mm 5MP lens I bought for the Maxi with the Mobius 1. Noticeably sharper results, may not use the Maxi for telephoto purposes after all. Will post videos from the new 5MP lens in the appropriate thread tomorrow.
 

fatpanda

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Daytime with lens B profile.
 
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