Original Mobius night recording with 4mm ~ F1.2 lens (!)

What about this one?

2017 Top Fashion Hot Sale Mega Pixels 1/2.5 Inch F1.6 M12 Cctv Board Camera Lens 12mm With Ir Cut
http://s.aliexpress.com/3qieaMz6
(from AliExpress Android)
12% distortion and 3 MP, to much distortion and not enough MP's. I really want f1.4 even though I said f1.6.
 
12% distortion and 3 MP, to much distortion and not enough MP's. I really want f1.4 even though I said f1.6.
Why not just buy the same 2MP 12mm F1.6 lens as @kamkar1? He has proven that it works well for his x cam. Should be ok for Mobius too. It's a bit expensive though.
 
I think its sold out.

But yes a 2 mpix lens on a 4 mpix sensor are not that bad, but i would noy expect much putting this lens on say one of my 12 - 16 mpix Sj action cameras.

Yes price seem steep, but its a lens jungle out there, and i figured if peau was selling it then it cant be all bad.
 
Why not just buy the same 2MP 12mm F1.6 lens as @kamkar1? He has proven that it works well for his x cam. Should be ok for Mobius too. It's a bit expensive though.

It's not a question of buying what someone has, it's buying what I want and works at it's best with the Mobius camera sensor.

@Dashmellow One thing I should say here is that I see some of you guys talking about lenses with 1/1.7" (Diagonal 9.50mm image circle) and 1/1.8" (8.93mm image circle. I have read statements in checking out lens that said these formats were only for certain camera censors and most others that said the MAX sensor circle was for 1/2" sensors which is diagonal of 8.00mm.
It's possible this is only for certain focal length lenses, I'm not sure of the impact because they never said. Must have something to do with the building of the lens with certain components
I don't think they said this for nothing so if you are buying a lens with those formats (larger then 1/2"-- Diagonal of 8.00mm) it might be wise to ask the Manufacture if it has any bearing on what you are using the lens on. So, I guess they would want to know the camera sensor size you are using.

This is a little out of my league so I'll give out a @ call for dashmellow.
 
some difficult situations to read license plates, all 3 camera's: 1080/30 and WDR or HDR mode ON. (Mobius F1.2 is EXP +15, Viofo EV 0, Joovuu EXP o)

Guess who wins, just freaking brilliant!

I posted these on Onedrive and let you share these images, you know.... caus I don't want to clutter up this thread, and cause it's so freaking brilliant...!

The comparison with the Volvo at stand still at the red lights is just to show it's not a focus thingie.....

https://1drv.ms/f/s!AuH5fyr_6CYMhYIIuh9q1VxbbW2SFQ
 
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some difficult situations to read license plates, all 3 camera's: 1080/30 and WDR or HDR mode ON. (Mobius F1.2 is EXP +15, Viofo EV 0, Joovuu EXP o)

Guess who wins, just freaking brilliant!

I posted these on Onedrive and let you share these images, you know.... caus I don't want to clutter up this thread, and cause it's so freaking brilliant...!

The comparison with the Volvo at stand still at the red lights is just to show it's not a focus thingie.....

https://1drv.ms/f/s!AuH5fyr_6CYMhYIIuh9q1VxbbW2SFQ
Whilst the Mobius is giving you more readable plates, note that its metering is giving you a darker image than the others which is losing information in shadow areas. Under exposing is helping the Mobius to maintain a short exposure time that reduces motion blur. However that is only part of the equation. The F1.2 lens is certainly performing very well.
 
Whilst the Mobius is giving you more readable plates, note that its metering is giving you a darker image than the others which is losing information in shadow areas. Under exposing is helping the Mobius to maintain a short exposure time that reduces motion blur. However that is only part of the equation. The F1.2 lens is certainly performing very well.

:D

Keep in mind I travel at about 80 kph, and so does the upcoming traffic.....
 
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It's not a question of buying what someone has, it's buying what I want and works at it's best with the Mobius camera sensor.

@Dashmellow One thing I should say here is that I see some of you guys talking about lenses with 1/1.7" (Diagonal 9.50mm image circle) and 1/1.8" (8.93mm image circle. I have read statements in checking out lens that said these formats were only for certain camera censors and most others that said the MAX sensor circle was for 1/2" sensors which is diagonal of 8.00mm.
It's possible this is only for certain focal length lenses, I'm not sure of the impact because they never said. Must have something to do with the building of the lens with certain components
I don't think they said this for nothing so if you are buying a lens with those formats (larger then 1/2"-- Diagonal of 8.00mm) it might be wise to ask the Manufacture if it has any bearing on what you are using the lens on. So, I guess they would want to know the camera sensor size you are using.

This is a little out of my league so I'll give out a @ call for dashmellow.

@Lola, I'm not really sure what you are getting at here.

As we've talked about, the image circle is the cross section of the cone of light transmitted by a lens onto a perpendicular target such as film or a digital camera sensor. Basically, every lens, regardless of it's focal length throws a circle of illumination of a particular size depending in its particular design and purpose. Lenses are designed so they will throw an image circle which can accommodate different sensor aspect ratios such as 3:2, 4:3, 16:9, etc., as well as sensors of different sizes. There are all different kinds of lens designs intended for all different kinds of cameras. The field of optical design is highly complex and complicated as it can involve a wide array of variables depending on how any given lens will be used on any given type of camera sensor combination according to how the camera is intended to be used. It becomes even more complicated when you consider factors such as variable focusing, variable apertures and the quirks and characteristics of particular focal lengths. Wide angle lenses tend to throw a larger circle of coverage, for example.

The thing you need to keep in mind is that we are talking about M12 (S-mount) lenses that we have in our dash cams which are fixed focus and of fixed aperture. That makes it all very simple. All you really need to know when shopping for a lens with the proper coverage is that it will project an image circle that is big enough to cover your particular sensor so that it will not cause vignetting. (Cutting off the corners of your image.) But if the lens you choose happens to project an image that is WAY bigger than the sensor it was specifically designed for, all that will happen is that it will act as if it is providing the greater magnification of a more telephoto lens than if it fit perfectly into the entire circle of coverage because the smaller sensor will only be a smaller section of the circle.

Here's a demonstration image I made:

Imagine that you are looking at the circle of coverage from a lens designed specifically for a 1/2" sensor. (seen in white)

If you install this same lens on a camera with a 1/3" sensor (seen in red) it will only record a smaller section of the available circle of coverage onto the smaller sensor, thus providing an image that has more of a telephoto effect.

So, if you were to buy an 8mm focal length lens that is designed for a 1/2" sensor it will act "perhaps" more like a 12mm focal length lens if installed on a camera with a 1/3" sensor. (I'm only guessing at the increased magnification, of course, but it's probably somewhere in the ballpark.)

image_circle.jpg

The telephoto effect demonstrated above can be a very good thing for our purposes because the center portion of a lens's circle of coverage always provides better optical performance than towards the outer edges of the circle. You'll get a sharper, brighter, more optically corrected image with less barrel distortion than it otherwise might have.

Also, since we are seeking faster lenses here with the largest possible aperture, we are much more likely to find larger apertures in shorter focal length lenses (such as @dirkzelf's ƒ/1.2 - 4mm here) than in longer focal length M12 lenses.
It is no accident or coincidence that you haven't been able to find the super wide aperture 12mm lens you have been looking for. ;)

@Lola, I've been watching you go through this whole lengthy process and I'm really impressed that you are such a ferret for information that you have been going to so much trouble to learn all about this and find what you want. The truth of the matter though is that I think you are making yourself a bit crazy over all this after so much time. To be honest with you I think such things as talking to manufacturers about building you a custom lens is kind of over the top IMHO. The Mobius is a great camera and I love the platform, as you know, but there is a limit to what the Mobius can achieve even with the finest lenses. I recommend finding a decent lens from a reliable vendor on AliExpress. That's the one source that seems to have these specialty lenses available and I'm sure you'll be very happy with it. Personally, after looking around, I'm considering a 6mm ƒ/1.2 StarLight similar to @dirkzelf's choice. I think it will provide enough of a telephoto for my purposes and it appears so far to be the fastest lens available in a longer focal length. Then again, that varifocal 2.8 mm - 12mm IR lens I've been experimenting with has provided remarkable optical performance, especially considering that it only cost me $7.50. And it's an ƒ/1.4 which isn't too shabby for a 12mm and it's designed specifically for a 1/3" sensor! I'm considering installing an IR-cut filter on it once I'm done with my IR experiments. It might be all I need in a Mobius telephoto? .....or perhaps you too for that matter. :)
 
@Lola

There's one 12mm f/1.2 available on AE but without the IR filter, you could inquire if seller is willing to add one before dispatch.

https://www.aliexpress.com/item/1-3...-M12-Mount-Lens-For-Security/32767100549.html

Interesting find! The shape and design of this lens is unusual too. The one concern might be what appears to be an unusually short back focal distance of 0.2. I'm not really sure what that means in practical terms. Certainly the lens is cheap enough to find out.

bf.png
 
Interesting find! The shape and design of this lens is unusual too. The one concern might be what appears to be an unusually short back focal distance of 0.2. I'm not really sure what that means in practical terms. Certainly the lens is cheap enough to find out.

View attachment 34197
A back focal distance of 0.2mm doesn't leave much room for focusing error, or for an IR filter.
 
Interesting find! The shape and design of this lens is unusual too. The one concern might be what appears to be an unusually short back focal distance of .2. I'm not really sure what that means in practical terms. Certainly the lens is cheap enough to find out.

There's no indication of whether that is a megapixel lens or not

I've messaged the seller asking the MP count and whether an IR filter can be installed at their end, let's see.
 
Personally, after looking around, I'm considering a 6mm ƒ/1.2 StarLight similar to @dirkzelf's choice. I think it will provide enough of a telephoto for my purposes and it appears so far to be the fastest lens available in a longer focal length.
I have a 4mm and 6mm F1.2 arriving from AE this week for testing on my Mobius cameras :)
 
I'm still trying to understand all this but some of it is making it's way into my dense brain :ROFLMAO: Is "back focal length" a normally listed lens parameter? Is there one length or a range of lengths witch would work with most dashcams (specifically Mobius and perhaps G1W-H and others)? I've seen where Kamkar1's lens doesn't engage a lot of threads in his X and I presume the opposite could occur too so knowing which back focal length is needed seems to be important in making a good lens choice ;)

Phil
 
I'm still trying to understand all this but some of it is making it's way into my dense brain :ROFLMAO: Is "back focal length" a normally listed lens parameter? Is there one length or a range of lengths witch would work with most dashcams (specifically Mobius and perhaps G1W-H and others)? I've seen where Kamkar1's lens doesn't engage a lot of threads in his X and I presume the opposite could occur too so knowing which back focal length is needed seems to be important in making a good lens choice ;)

Phil
See this example M12 lens data sheet I found on the web. Back focal length is the physical distance (in air) between the rear lens element and the sensor - 6.68mm. The flange back length is the distance between the back of the lens barrel and the sensor - 6.40mm. The depth of the M12 threaded lens holder on the Mobius is about 12mm (thanks @Dashmellow).

upload_2017-10-30_9-30-5.png

If the BFL is too great then the lens barrel will not properly engage the threaded socket. I fear that may be the case for the 25mm lens I purchased from AliExpress (spec below) so I may need an extender or a new lens holder to fit this lens.

upload_2017-10-30_9-40-45.png
 
Interestingly, the opposite Back Focal Length problem can present itself, depending upon the lens. I have a small collection of different M12 lenses I've collected over the years of different focal lengths and qualities. One time while installing one into a camera as part of a DIY experiment I screwed the lens in so far during my attempt to focus that the back of the lens made contact with the sensor. (luckily with no apparent damage) The Back Focal Length of that particular lens was so short that I almost couldn't find a way to achieve focus at all. Close examination of the back of the lens revealed that the rear element of the lens was recessed and the design of that lens required it to be just about touching the sensor to be in focus. This was partly because I was installing the lens in a camera it was never designed for.

I fear the interesting lens @harsh posted about yesterday might present a similar problem. It appears to be a highly specialized and unusual lens. I've never seen a longer focal length M12 lens that looks quite like it.

More than two years ago when I installed a Mobius C lens into a G1W-H I spoke about how I went through several different optional lenses attempting to installed them in the camera, in this case because of the design of the module base. "I ran into an issue where I could not screw the lenses into the module base threads far enough to achieve focus. This was partly because of the barrel length and thread depth on the lenses and partly because of the thread depth on the module." That particular module housing was apparently intended for a particular lens with a particular Back Focal Length and so the threads were only cut half way down the barrel tube. Only the Mobius C lens would work for me in that camera. This experience was my first direct encounter with the Back Focal Length issue.

All the other cameras I've ever owned (except view cameras) have had a bayonet or fixed thread mount intended for bespoke lenses designed for particular cameras. Back Focal Length is at play in every camera lens everyone has ever owned but it's not something most people would ever have to think about except the rare photographer who might have to worry that the back of certain types of specialized lenses could be hit by the mirror of a DSLR as it is flipping up. M12 lenses screwed into randomly threaded lens barrels are a whole different kettle of fish.
 
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