Viofo A139 Pro - First Impressions

[TonyM]

I bought the Viofo A139 Pro 1CH soon after it was released.

This is my first dashcam purchase in 6 years, after a few years of testing a number of pre-release cameras including the Viofo A129 Duo, A129 Pro & 5MP A139. I have stopped testing because I simply don't have the spare time any more. However I'm happy to share a few of my personal thoughts after the first week of using the A139 Pro.

Executive Summary
The A139 Pro feels like a decent upgrade over both the regular A139 and the A129 Pro. It is the best implementation of HDR that I have seen in a dashcam, however it is not perfect and still has limitations.

I really like the 21:9 aspect ratio of the 4K 1600p video option, which is wide but not too tall.

Motion blur is higher than I expected, but considering the overall performance I'm happy with my purchase. For additional detail and in a limited FOV, I will be using an 8mm telephoto camera alongside the A139 Pro.

Setup
I am running the A139 Pro in single channel mode for best performance. My intention is to have a regular A139 as a rear camera, then use my DIY 8mm and 6mm remote telephoto cameras at the front and rear respectively.

Both A139's will be powered by a Viofo hardwire kit connected to a PowerCore dashcam battery.

 

[Panzer Platform]

Right on Tony,
Laying down your own cash, for the first time in 6 years on a dash cam already speaks volumes. lol
-Chuck

 

[TonyM]

Right on Tony,
Laying down your own cash, for the first time in 6 years on a dash cam already speaks volumes. lol
-Chuck

Step by step I will replace all the 'free' test cameras with ones that I buy, chosen specifically to suit my preferences. I decided to start with the front camera.

 

[TonyM]

A139 Pro 1CH HDR

Good exposure in high contrast winter sunlight. No CPL filter.

 

[TonyM]

A139 Pro 1CH HDR - Tunnel

HDR at work driving through a tunnel. Overall exposure is good by combining fast and slow exposures, but this is still a difficult environment for number plate capture.

 

[Frederick]

The tunnel footage is somewhat disappointing. It's practically impossible to read the license plates of the vehicles in there. I hope future firmware updates improve the footage still.

 

[TonyM]

A139 Pro HDR-on vs A139 HDR-off

Looking at the tunnel footage again, I was curious to see what difference the HDR made. First up is the A139 Pro with HDR on, and the 5MP A139 with HDR off.





Now at 100% (4K left, 5MP right):






I'm not expecting 100% number plate capture with this camera. Overall I think the combination of 4K detail, low noise and high dynamic range will be useful to show what is happening on the road or around the car in a variety of lighting conditions.

 

[TonyM]

A139 Pro HDR-off vs A139 HDR-off

I decided to drive through the tunnel again after turning off HDR on the A139 Pro, to see how the Starvis 2 sensor performs compares to the IMX335 Starvis 1. The scene exposure is almost identical, however there is more detail and less blur across the A139 Pro video due to the higher sensitivity permitting shorter exposures for each frame.

100% crops:

 

[Nigel]

but this is still a difficult environment for number plate capture.

Yes, in those examples the HDR works well for the tunnel mouth, while the number plate reading is better on the Pro with or without HDR!

Still not perfect though, hopefully the number plate reading will be improved with firmware updates. I believe the issue limiting the plate readability at the moment is the flicker mitigation for preventing LED lamps and sodium lamps from flickering in the video, needs turning down a bit I think, but then people might start complaining about flickering lights on the video image...

 

[TonyM]

Yes, in those examples the HDR works well for the tunnel mouth, while the number plate reading is better on the Pro with or without HDR!

Still not perfect though, hopefully the number plate reading will be improved with firmware updates. I believe the issue limiting the plate readability at the moment is the flicker mitigation for preventing LED lamps and sodium lamps from flickering in the video, needs turning down a bit I think, but then people might start complaining about flickering lights on the video image...

It is worth noting that I drive a rather old car that has clouded headlamps that are much less bright than most other cars - they only just passed the MOT this year after a special clean. I always notice a big difference in road illumination at night whenever I drive my wife's car.

If my headlights were much brighter I'm sure it would help the HDR function to use shorter exposures for the highlights.

 

[Nigel]

If my headlights were much brighter I'm sure it would help the HDR function to use shorter exposures for the highlights.

Yes, with brighter lights reflecting off the plates, your multi-exposure HDR would assist with the plate reading. As it is, it doesn't appear to have helped at all. I think the current firmware needs quite bright lights, and they also have to have beams that illuminate the plates, while older headlamps, pre-LED, tend to avoid illuminating the front of the approaching cars, unless maybe they have self-leveling mechanisms.

It is worth noting that I drive a rather old car that has clouded headlamps that are much less bright than most other cars - they only just passed the MOT this year after a special clean. I always notice a big difference in road illumination at night whenever I drive my wife's car.

If the plastic lenses have clouded then give them a good polish with some fine abrasive polish, they can end up like new!
Although you are likely to have to repeat it once a year once the surface coatings have gone.

Loss of light is often due to deteriorated mirror surfaces though, and that is much harder to fix.

 

[TonyM]

A139 Pro 1CH HDR-on - Early Evening

Driving through my village just after sunset at slow speed <30mph, the results are similar to driving through the tunnel. My headlights do not appear bright enough to take advantage of the HDR potential of this camera. The video does have good shadow exposure and low noise.

Comparing the A139 Pro to the A139, both with HDR-ON, you can see the difference in exposure durations by looking at the length of the light trails. In this lighting, the regular A139 does better with highlight detail, but the Pro performs better in the shadows.





100% crops:

 

[CuriousGeorge]

Tony, These are awesome comparisons, and will save me and others a lot of time for me to decide whether not to use HDR. Thank you so much! In my (unprofessional) opinion I think the A139 Pro looks better with HDR On. Just my opinion so far.

Have you considered experimenting with lowering the exposure by -0.3 or -0.6 with HDR on / off? I have been wondering if that makes things better or worse for capturing plate numbers. The surrounding details may drop off, but of course we're not trying to get a "roadtrip video". Do you think this is worthy of a test?

 

[TonyM]

Have you considered experimenting with lowering the exposure by -0.3 or -0.6 with HDR on / off? I have been wondering if that makes things better or worse for capturing plate numbers. The surrounding details may drop off, but of course we're not trying to get a "roadtrip video". Do you think this is worthy of a test?

I often set my front cameras to EV-0.3 to compensate for the dark hood and dash in the lower part of the frame. Now that I'm using the 21:9 format I'm not so sure this is necessary, but I will try it at some time.

I'm curious to see whether the metering changes when swapping between 3840x1600 and 3840x2160.

 

[Nigel]

I'm curious to see whether the metering changes when swapping between 3840x1600 and 3840x2160.

Difficult to test! Need someone with two A139 Pro...

Setting EV negative and using 60fps might possibly reduce the exposure in some situations, but they are very unlikely to reduce the motion blur, since the motion blur on this camera is not controlled by the exposure, it is controlled by the flicker mitigation. Given the high dynamic range, and the flicker mitigation, I doubt that changing EV negative or using 60fps has any advantage, it will simply darken the recorded video.

I think the A139 Pro looks better with HDR On. Just my opinion so far.

There are times when the HDR has some slight negative effects, but most of the time it is either positive or neutral, so on this camera, and I expect any Starvis-2 camera, HDR is definitely best left left ON at all times, day and night.

 

[Panzer Platform]

My headlights do not appear bright enough to take advantage of the HDR potential of this camera.

In the US installing LED headlight bulbs in a standard halogen reflector housing headlight assembly is illegal because there are currently no LED replacement headlight bulbs that are DOT compliant. This is because usually the end result is a poor light pattern, or scattered light that projects directly into the eyes of oncoming motorists, and pedestrians.

Do people buy cheap Amazon LED Headlights bulbs, and do it anyway? Yes.
I did it in my cars but it took trying out 10 different brands of LED bulbs to find an acceptable light pattern, and fine tuning the beam adjustment horizontal, and vertical to get the bean pattern hot spots on the road, and not blinding to other motorists.

In the interest of experimenting with the A139 Pro's HDR would you be willing to try a pair of LED headlight replacement bulbs?
I've tested over 50 different brands on my YouTube channel, so I have a good idea which ones are the best.
-Chuck
Here's a clip;

 

[TonyM]

In the interest of experimenting with the A139 Pro's HDR would you be willing to try a pair of LED headlight replacement bulbs?

No, because I really don't have the time, and I plan to sell (i.e. scrap) the car in the next year or two.

I may try Nigel's suggestion of polishing the headlamps, although that has already been done recently by the workshop to meet the minimum roadworthy standard so I might be stuck with what I have.

 

[TonyM]

I'm curious to see whether the metering changes when swapping between 3840x1600 and 3840x2160.

Difficult to test! Need someone with two A139 Pro...

I was thinking of sitting in a car park under relatively constant lighting conditions, swapping between 3840x1600 and 3840x2160, just to see if the metering pattern is identical. Does the A139 use the upper or lower 280 pixels when metering for 2160 height video? Does it use the full 2160 pixel height for metering at all times, then crop out the middle 1600 when encoding the video?

 

[Nigel]

Does the A139 use the upper or lower 280 pixels when metering for 2160 height video? Does it use the full 2160 pixel height for metering at all times, then crop out the middle 1600 when encoding the video?

It will use a patterned metering, with priority set on the road ahead, some influence from the sides towards the bottom, and more or less ignoring the upper half of the image. I don't know exactly what the pattern looks like, but it probably doesn't make much difference if it uses the bottom 280 pixels (off the bottom of the 1600 image) for 1600 metering or not! It will make far more difference if you move the horizon up/down 50 pixels from the vertical centre.

Due to the high dynamic range, I suspect that adjusting the horizon is far less important than with older cameras, but I haven't tested that yet.

 

[Nigel]

then crop out the middle 1600 when encoding the video?

Thankfully, it does appear to crop out the middle, and not the top or bottom, as some cameras do!