A139 (Pro) Telephoto Remote Camera

[Dashmellow]

well it is just you guys that use the zoom lenses, i have always used a fixed lens in 8 or 12 mm flavor.

I don't recall you ever posting any of your results. Anything worth showing? Which camera too?

BTW, my post was based on your use of the word "zoom" in your post.

kamkar: I would be very interested in a front / front zoom system

 

[kamkar]

Hehe yeah i know its a bit of a stretch me calling it zoom lens when it if fixed, i guess its a result of the #2 language thing as it is just a zoomed in view i get not the actual option to choose any zoom level.

I have always used the little box cameras for this, though the very first mobius did not see any modding, but from the Joovuu X cam it took off, and after the M2 died i use the mobius maxi for the 12 mm lens.

Or to be more honest used to, cuz the maxi is right here in front of me, and so far it have taken me a few months to try and put a new battery into it ( solder 2 wires up and then put the thing back together )

 

[TonyM]

A couple of days ago I repositioned the 6mm camera. It was high on the driver's side (right) at the very top of the wiper arc, but rather obvious from both inside and outside of the car.

Now it is mounted on the frit on the left side and barely visible from the outside. As you can see, the lens is almost touching the glass. If I want to try a larger 8mm lens I will need to modify the mount with spacers.



Moving the camera down a bit now shows the front edge of the car along the bottom of the video, as seen in this comparison with the A139 main camera. Whilst I think this is useful to show context in a telephoto video if viewed on its own, I would rather have a bit more reach from an 8mm lens.





This example looking towards the sun also demonstrates how the metering on a telephoto camera is less affected by bright areas in the sky (no CPL on either camera, both set to EV+0).

 

[TonyM]

We haven't tried telephoto lens with STARVIS-2 sensor yet.
We are also testing other STARVIS 2 sensor now, so we can do such testing in the future.
And maybe in 2023, it is possible to support real HDR for the rear cam with new hardware, it will make much more sense to use a telephoto lens.

I will share the lens spec here, and if some one wants to test, we can get some lenses and offer them for free.

I will be happy to test telephoto lenses. Soon my setup will be A139 Pro 4K front and A139 5MP rear, so I will have 4 spare channels for remote cameras!

 

[Julian23]

This example looking towards the sun also demonstrates how the metering on a telephoto camera is less affected by bright areas in the sky (no CPL on either camera, both set to EV+0).

Impressive comparison. Looking very nice.

 

[TonyM]

If Viofo were to produce a dual wide/tele commercially successful dash cam it would reallly need a carefully selected primary lens of a particular focal length which would be a simple "plug & play" install. Ideally, it would be the equivalent of an 8mm lens AOV as many of us have been talking about, depending upon the size of the sensor.

I was thinking about this whilst browsing AliExpress for new telephoto lenses. Regarding myself as an enthusiast, I found I was looking at fast 'starlight' lenses with apertures ranging F1.5 to F2.0. However we know that such lenses can be difficult to focus accurately, and they may have optical defects such as distortion & chromatic aberration, especially towards the edges of the frame.

For a successful commercial product that can achieve repeatable quality in mass production I think Viofo might be better looking at F2.0 to F2.8 lenses. It will be interesting to see how they perform with 4K or 5MP Starvis 2 sensors.

 

[Nigel]

For a successful commercial product that can achieve repeatable quality in mass production I think Viofo might be better looking at F2.0 to F2.8 lenses. It will be interesting to see how they perform with 4K or 5MP Starvis 2 sensors.

If using a 4K sensor, what focal length would you choose?

 

[Julian23]

Soon my setup will be A139 Pro 4K front and A139 5MP rear, so I will have 4 spare channels for remote cameras!

So you could test 2 different lenses with the remote cameras in each direction and get side by side comparisons?

 

[TonyM]

If using a 4K sensor, what focal length would you choose?

I think the physical sensor size is more relevant than the resolution when choosing the focal length.

My current test setup is a "nominal 6mm lens" that according to the retailer has an Angle of View of 65.8 °x56.5 °x30.5 ° on the IMX291 sensor in the A139 remote camera:

https://www.aliexpress.com/item/32663560773.html

I'm now looking into the angle of view that an 8mm lens creates with a 1/2.8" sensor (e.g. IMX291, IMX335, IMX415 or the new Starvis 2 IMX675).

The 4K IMX678 in the A139 Pro is much larger at 1/1.8", so would require a different focal length lens to achieve the same angle of view as 8mm on 1/2.8" - perhaps 12mm?

 

[TonyM]

There are a few 3 MP 8mm starlight lenses available now from Treeye and Yumiki that I don't recall seeing when I purchased the two different 6mm versions I own. There's a 4K 8mm available now too.(10.5 mm BFL)

Yumiki M12 CCTV 3MP 8mm lens F1.5 Focal Length 8mm Sensor 1/2.5"​

Starlight Lens 8mm CCTV Lens HD 3.0Megapixel IP Cameras Lens F1.5 M12​

4K Lens 12Megapixel Fixed M12 Lens 8mm Long Distance View 1/1.7 inch For IMX226 IMX178 4K IP CCTV camera or 4K Action Camera​

I'm tempted by these lenses so far:

8mm, F1.8

https://www.aliexpress.us/item/2251832667641499.html

6.8mm, F2.5

https://www.aliexpress.us/item/3256802634220588.html

 

[Dashmellow]

I'm tempted by these lenses so far:
View attachment 62363
8mm, F1.8

https://www.aliexpress.us/item/2251832667641499.html

View attachment 62364
6.8mm, F2.5

https://www.aliexpress.us/item/3256802634220588.html

There have been a lot of interesting high quality M12 lenses coming onto the market as action cams and drones have become professional platforms rather than just existing in the realm of hobbyists and average consumers.

Here are a few interesting ones if price is no object.

1/1.8 Inch 8mm 16Megapixel Lens HFOV 50D No Distortion High Resolution S Mount IR-CUT​

8.25mm 4K Lens 41 Degree HFOV 16MP NDVI M12 Mount​

4K Resolution Lens 7.2mm F/2.5 47D HFOV 10MP No Distortion Flat Lens 1/2.3"​

 

[TonyM]

There have been a lot of interesting high quality M12 lenses coming onto the market as a action cams and drones have become professional platforms rather than just existing in the realm of hobbyists.

Here are a few interesting ones if price is no object.

Interesting, but I can't justify the cost for this little project. I need to remember it's only a 2MP IMX291 in this remote camera.

 

[Dashmellow]

Unfortunately, the 8K Productions store on AliExpress doesn't offer much in the way of specs and technical data on those pricey lenses.

Peau Productions however offers many of those same high end lenses (at better prices in some cases) but provides plenty of technical data and specifications. (Including aperture!)

 

[Dashmellow]

Interesting, but I can't justify the cost for this little project. I need to remember it's only a 2MP IMX291 in this remote camera.

I was responding to your posting of 4K lens candidates, assuming you had them in mind for a future project.

 

[kamkar]

Them lenses not cheap but on the other hand a lens like that should in essence last forever, so not a bad deal after all.
Okay growing sensor sizes ASO may render a lens useless.

I am pretty freaked by the lenses they manage to put on some pretty hefty sensors in phones, in a phone that are a "few" mm thick
The Optical zoom lenses in some phones are also pretty cool, again done in very little space.

O and not forgetting the new in screen front cameras, that you cant even see as its behind the screen and do not have a cut out or hole.

Maybe some of that ingenuity should be diverted towards sustainable power, CUZ lets face it the solar and wind are never going to cut it.

 

[TonyM]

I was responding to your posting of 4K lens candidates, assuming you had them in mind for a future project.

OK, understood. I don't have a future project in mind, yet However if I go for the 1/1.7" 4K 8mm it had occurred to me that one day I could use it on the 4K Starvis2 IMX678 1/1.8" in the A139 Pro

 

[Dashmellow]

OK, understood. I don't have a future project in mind, yet However if I go for the 1/1.7" 4K 8mm it had occurred to me that one day I could use it on the 4K Starvis2 IMX678 1/1.8" in the A139 Pro

Be aware that very high megapixel lenses designed for 4K will very likely provide inferior results on a lower megapixel sensor. Lens resolution and sensor resolution need to be fairly well matched due to pixel size on the sensor. Too much resolving power from a lens projecting onto larger pixels on the sensor doesn't provide higher resolution and the result will be more or less the opposite.

 

[Nigel]

The 4K IMX678 in the A139 Pro is much larger at 1/1.8", so would require a different focal length lens to achieve the same angle of view as 8mm on 1/2.8" - perhaps 12mm?

Although the sensor is much larger, you would require the same focal length lens to get the same number of pixels per number plate, and thus the same plate readability. The question is, would you choose to have more magnification, or more field of view?

 

[TonyM]

A139 Main Camera & Remote 6mm F1.2

I think this side-by-side example shows some of the positive and negative things about using a telephoto dashcam. However, when used in combination with a primary camera, together they have the potential to complement each other rather than simply duplicate the same information in both video streams.

Positive:
- Increased detail in the middle of the view directly ahead of the car
- Increased chance of plate capture - we can identify the first red car, but not the second one
- Bright highlights are a larger part of the scene, so the metering adjusts and captures highlight detail

Negative:
- Cropped view loses information at the sides, particularly when driving around corners
- Exaggerated movement when bouncing over bumps or turning sharp corners
- Metering for highlights means that shadows are very dark

Vertical Motion Blur


Limited Horizontal View


Red Car 1


Red Car 2


Highlight Metering 1


Highlight Metering 2


P.S. Changing the camera position has fixed the curious ghosting effect seen previously, so I suspect there was a chip, scratch or other defect in the windscreen near my original telephoto camera placement.

 

[Julian23]

The negative points are nearly all covered by the main camera.
All these videos make me want to try this myself.