The A119S (hardware version 1) f1.6 135 degree Lens

OldMan01

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I think a lot of issues of the A119S have their start with the lens. It seems that Viofo wanted to emphasize superior low light performance, starting with the sensor and enhancing this with the 135 degree f1.6 lens which is the brightest used in this type of device so far. But it has not worked out well.

The sample image is a video frame capture (firmware version 1.2) when the vehicle is parked, so motion is minimal. As noted by BCHobbyist, the image is "softer" on the left than on the right. But if you look at the far right, you will see some softening as well.

When I first looked at images like this, I thought the dash-board looked reasonably sharp, and so I thought that re-focusing the lens might help. But looking at this, and other images more closely, the lower far corners of the images, which are dashboard, are not that sharp and lack detail. So refocusing the lens might help a bit, but not really that much.

The "fall-off" of sharpness and detail off-axis (away from the center of the image), seems to be more than just a focus and depth of field issue, it is a lens design limitation. It would seem that to make a lens this small, with a f1.6 aperture and 135 degree field of view at a "low" cost, resulted in a lens that could not provide corner to corner sharpness capable of fully support 1080p resolution, or even 720p resolution as shown is this sample image.

I do not like this lens, and for now, I have "retired" my A119S and gone back to the A118C for now. Someday, if I have time I will try to replace the lens with something better, but I cannot do it right now.

My advice for Viofo is as follows:

Goal:

I think a reasonable goal is to have a lens that will provide corner to corner sharpness and detail, at least enough to exceed the needs at 720p. If you can exceed the needs at 1080p, then that is even better, but the cost is always an issue.

What to Do:

If the lens in the A119 is better, then just use that lens for this device. That has obvious cost advantages.

If you want to stick with the 135 degree angle of view (which I like) and this lens design, you could ask the lens maker to try adding an aperture mask and see if that helps the corner sharpness. The effect of an aperture reduction is not predictable. It is not the same as "depth of field", though it is often similar. If you are lucky, then adding an f1.8 aperture might be enough to make the lens adequate. I am not that hopeful. I think it would take at least f1.9. It might be better to consider a similar but different lens.

Trying to retrofit an aperture is not going to help existing units. The aperture will have to be put inside the lens, and I do not think the lenses can be disassembled.

It is important to make this change as soon as you can because it will affect firmware issues. You will need less "sharpening". It will also affect optical motion detection, and probably "Lane Departure", and maybe even the "Front Collision" detection systems.

Also it is just a good idea to make "friends" (happy customers) when possible by producing the best products that you can make.
 

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I think a lot of issues of the A119S have their start with the lens. It seems that Viofo wanted to emphasize superior low light performance, starting with the sensor and enhancing this with the 135 degree f1.6 lens which is the brightest used in this type of device so far. But it has not worked out well.

The sample image is a video frame capture (firmware version 1.2) when the vehicle is parked, so motion is minimal. As noted by BCHobbyist, the image is "softer" on the left than on the right. But if you look at the far right, you will see some softening as well.

When I first looked at images like this, I thought the dash-board looked reasonably sharp, and so I thought that re-focusing the lens might help. But looking at this, and other images more closely, the lower far corners of the images, which are dashboard, are not that sharp and lack detail. So refocusing the lens might help a bit, but not really that much.

The "fall-off" of sharpness and detail off-axis (away from the center of the image), seems to be more than just a focus and depth of field issue, it is a lens design limitation. It would seem that to make a lens this small, with a f1.6 aperture and 135 degree field of view at a "low" cost, resulted in a lens that could not provide corner to corner sharpness capable of fully support 1080p resolution, or even 720p resolution as shown is this sample image.

I do not like this lens, and for now, I have "retired" my A119S and gone back to the A118C for now. Someday, if I have time I will try to replace the lens with something better, but I cannot do it right now.

My advice for Viofo is as follows:

Goal:

I think a reasonable goal is to have a lens that will provide corner to corner sharpness and detail, at least enough to exceed the needs at 720p. If you can exceed the needs at 1080p, then that is even better, but the cost is always an issue.

What to Do:

If the lens in the A119 is better, then just use that lens for this device. That has obvious cost advantages.

If you want to stick with the 135 degree angle of view (which I like) and this lens design, you could ask the lens maker to try adding an aperture mask and see if that helps the corner sharpness. The effect of an aperture reduction is not predictable. It is not the same as "depth of field", though it is often similar. If you are lucky, then adding an f1.8 aperture might be enough to make the lens adequate. I am not that hopeful. I think it would take at least f1.9. It might be better to consider a similar but different lens.

Trying to retrofit an aperture is not going to help existing units. The aperture will have to be put inside the lens, and I do not think the lenses can be disassembled.

It is important to make this change as soon as you can because it will affect firmware issues. You will need less "sharpening". It will also affect optical motion detection, and probably "Lane Departure", and maybe even the "Front Collision" detection systems.

Also it is just a good idea to make "friends" (happy customers) when possible by producing the best products that you can make.


My video looks the same as yours on the sides,but i'm a total noob to all of this,so i read all the posts in here and try to absorb what info i can. I hope Viofo will fix this issue.
 
the "F" is about distance range where the focus is
as F is lower (more light through) as less distance range is in the focus
example: F8 1m-4m in focus; F1.6 1m-1.5m only in focus

that how I got it from my old photography days
so, sides will be out of focus, unless at t he same distance as in the center - IMHO
 
the "F" is about distance range where the focus is
as F is lower (more light through) as less distance range is in the focus
example: F8 1m-4m in focus; F1.6 1m-1.5m only in focus

that how I got it from my old photography days
so, sides will be out of focus, unless at t he same distance as in the center - IMHO

What causes a video to appear to be bent in towards the center,such as a telephone poll on either side of the video..?? The poles appear a bit curved and not straight..??
 
What causes a video to appear to be bent in towards the center,such as a telephone poll on either side of the video..?? The poles appear a bit curved and not straight..??
"Fish eye" - as wider lenses > 90 as more curve will be - it's lenses
the same you see in GoPro with wide angle , but software can kind of correct it
and in dashcams it's 135-170
 
"Fish eye" - as wider lenses > 90 as more curve will be - it's lenses
the same you see in GoPro with wide angle , but software can kind of correct it
and in dashcams it's 135-170

Thank you for this info. At least I know why my videos look that way now.
 
Yes, you are right.
An improved F1.8 aperture lens will be help, that's what we are working.
 
Yes, you are right.
An improved F1.8 aperture lens will be help, that's what we are working.
So for those of us who have awaited the V2 (GPS logger issue) should now be expecting a possible V3 lens correction?
 
The lens quality is improved from last year, no big difference for news lens, but good for quality control.
 
Here are my two static non movement recordings A119s test, yes, the out of focus convergence type blur on right side and perhaps edges, I can live with a little blur on the edges, but not when it comes in too far.


 
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Limeybastard
Может второй ролик залить на файлообменник?
 
Limeybastard
Может не поняли ?
Оригинальное видео можно увидеть ?
 
you may use any free service to upload the file, just provide the link for download. I tried only WeTransfer.
I wouldn't know where to start, not young and computer clever anymore like my hay days 386/DX25 PC days lol

Perhaps he could provide a link for me to upload to?

Sent from my SM-T819Y using Tapatalk
 
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