How to use CPL Filter?

[jsmith]

If this has been asked, I'm sorry. I have purchased the CPL filter for the A139 Pro. There's a small white line on the plastic housing of the CPL. Does that line indicate "North" or "UP"? My window has tint, and I want to test out if CPL helps with eliminating the "Star Bust Effect" at night that makes plates harder to read.

Any assistance on how to use CPL and Proper Direction (White Line Meaning) is appreciated.

Thank you for reading my post and helping.

 

[Nigel]

The white line on the filter should line up with the white line on the lens barrel.
It can also be opposite, 180° and work correctly.
Sometimes the lines are slightly out of place, so if you want perfection, put some white paper on the dash and watch the live view while rotating the CPL, starting with the white lines aligned. You will never remove the reflections 100%, but it can make a big improvement.

It will not do much for star burst, the CPL removes reflections of the dash in the glass, also reflections in other people's windscreens, and off the road. It will also increase contrast and remove some haze, giving stronger colours.

Starburst is the result of dirt, grease, polish, or scratches in the glass caused by the wipers. A good clean of the glass using water with a tiny amount of detergent will get rid of the dirt and grease, don't reapply any polish. If the glass is scratched by wipers then it needs glass polish to remove the scratches which will take a bit of effort.

 

[jsmith]

The white line on the filter should line up with the white line on the lens barrel.
It can also be opposite, 180° and work correctly.
Sometimes the lines are slightly out of place, so if you want perfection, put some white paper on the dash and watch the live view while rotating the CPL, starting with the white lines aligned. You will never remove the reflections 100%, but it can make a big improvement.

It will not do much for star burst, the CPL removes reflections of the dash in the glass, also reflections in other people's windscreens, and off the road. It will also increase contrast and remove some haze, giving stronger colours.

Starburst is the result of dirt, grease, polish, or scratches in the glass caused by the wipers. A good clean of the glass using water with a tiny amount of detergent will get rid of the dirt and grease, don't reapply any polish. If the glass is scratched by wipers then it needs glass polish to remove the scratches which will take a bit of effort.

Hello.

Thank you for replying. I didn't know about white line on the camera. I now have aligned CPL White Line to A139 Pro white line on the barrel.

Front window is tinted. Not dirty. I think this effect is from the tint itself? Will CPL Help?

 

[Nigel]

The white line should go at the top, or bottom of the lens, doesn't matter which.

My A139 doesn't have a white line on the lens, so I'm not surprised that Viofo stock images don't have one, but I would expect there to be one on production units.

Will CPL help with this problem?

It may help a little, by reducing the brightness of the lights, but that is not what it is for.

Is that new tint? Or has it been on for ages?

 

[jsmith]

The white line should go at the top, or bottom of the lens, doesn't matter which.

My A139 doesn't have a white line on the lens, so I'm not surprised that Viofo stock images don't have one, but I would expect there to be one on production units.


It may help a little, by reducing the brightness of the lights, but that is not what it is for.

Is that new tint? Or has it been on for ages?

Production A139 Pro (my model was purchased) has a white line on the barrel. Also, the CPL filter has one, too. I have aligned the CPL and Camera White Line.

The tint is around 7-8 years old. Put on maybe 6 months to year after I purchased the vehicle.

 

[Nigel]

The tint is around 7-8 years old. Put on maybe 6 months to year after I purchased the vehicle.

The haze around the lights may be a result of the tint, maybe if you clean it fairly frequently, it has collected some minor scratching on it, but it is more likely that they go with the starburst lines.

The starburst lines are curved to match the path of the wipers, so are probably scratches in the outside of the glass, at 8 years old you have to expect some scratching. They would need polishing out to remove them. Completely removing them is impractical, easier to get a new windscreen, but some glass polish and a little effort can improve things, especially if you have a polishing machine. (Don't over do it though, and don't get the glass to hot by using a machine!)

 

[Dashmellow]

Living on a dirt road on a mountain in a rural area I've had to contend with pock marks in the glass from windblown dirt and fine rock particles as well as sand that the snow plows spread in the wintertime. One product I've found that works surprisingly well on the windscreen to subdue and reduce this kind of problem, at least temporarily is a polymer car polish called NuFinish that seems to fill the gaps and scratches in the glass. It is fast and easy to apply and doesn't need any sort of polishing machine. It doesn't completely "cure" the problem of pock marks and fine scratches but it can improve it for several months.

I don't know if this stuff is available in Europe but there is likely some similar product if it isn't.

The product I use is the "Once a Year Car Polish". Some of their other products might work even better for this task. This company has been around for decades, so their enduring popularity must mean that people are pleased with the results.

Nu Finish | Car Care

LEARN ABOUT NU FINISH® PRODUCTS Our polishes, detailing products and protectants will help clean, repair and protect your car's finish giving it that long-lasting showroom shine. See how our car-care products keep millions of loyal customers satisfied year after year.

nufinish.com

 

[jsmith]

Living on a dirt road on a mountain in a rural area I've had to contend with pock marks in the glass from windblown dirt and fine rock particles as well as sand that the snow plows spread in the wintertime. One product I've found that works surprisingly well on the windscreen to subdue and reduce this kind of problem, at least temporarily is a polymer car polish called NuFinish that seems to fill the gaps and scratches in the glass. It is fast and easy to apply and doesn't need any sort of polishing machine. It doesn't completely "cure" the problem of pock marks and fine scratches but it can improve it for several months.

I don't know if this stuff is available in Europe but there is likely some similar product if it isn't.

The product I use is the "Once a Year Car Polish". Some of their other products might work even better for this task. This company has been around for decades, so their enduring popularity must mean that people are pleased with the results.

Nu Finish | Car Care

LEARN ABOUT NU FINISH® PRODUCTS Our polishes, detailing products and protectants will help clean, repair and protect your car's finish giving it that long-lasting showroom shine. See how our car-care products keep millions of loyal customers satisfied year after year.

nufinish.com

Hi,

Thank you for responding. After @Nigel and you responded, I went ahead and cleaned the windshield to remove dirt and grease as a precaution. Other than a few rock chips, the windshield is in good shape cosmetically. but I could attempt a polish to remove any embedded grit or dirt. However, I think most of the issue is from light refraction of the tint?

I am testing the CPL filter to compare and see if it helps any. I guess the CPL is mostly meant for glare? First day Subjective testing (but maybe cleaning windshield helped, too) is that it is somewhat better at night. I plan to test with and without CPL to see if there's any noticeable improvement.

Second question.

Has Viofo implemented the full capabilities of Clear HDR on the 139 Pro?

 

[Nigel]

However, I think most of the issue is from light refraction of the tint?

The starburst is from the window wiper scratches, you can see from the angle and curve. You should be able to see this in real life too, it is just that you are used to it and your brain filters it out.

Has Viofo implemented the full capabilities of Clear HDR on the 139 Pro?

A139 Pro uses DOL-HDR, better than Clear HDR for dashcams, especially at night.
I suspect that it will be improved at some point, but I'm not sure if improvements will get into the A139 Pro or if it needs a processor update.

 

[jsmith]

The starburst is from the window wiper scratches, you can see from the angle and curve. You should be able to see this in real life too, it is just that you are used to it and your brain filters it out.


A139 Pro uses DOL-HDR, better than Clear HDR for dashcams, especially at night.
I suspect that it will be improved at some point, but I'm not sure if improvements will get into the A139 Pro or if it needs a processor update.

I looked up DOL-HDR. It says this is best for slow moving objects and Clear HDR for fast moving? Wouldn't you want ClearHDR for fast paced cars and license plates?

DOL HDR or Clear HDR: Which is Better for STARVIS 2 Dashcams? - VIOFO Official Website

DOL HDR or Clear HDR: Which is Better for STARVIS 2 Dashcams?

viofo.com

 

[jsmith]

@Dashmellow

I have another question (sorry). Trying to learn this camera. Do you by chance know the difference in Bitrate for Normal and High with a 3 Channel 1600P 2k / 1080P / 1080P on the A139 Pro? I see the chart on page 2 listing Maximum but not Normal and High. Right now, I have mine on "Normal" but wonder what bitrate difference may be between Normal --> High --- Maximum

https://dashcamtalk.com/forum/threads/a139-pro-test-review-pp.48049/page-2

 

[Dashmellow]

@Dashmellow

I have another question (sorry). Trying to learn this camera. Do you by chance know the difference in Bitrate for Normal and High with a 3 Channel 1600P 2k / 1080P / 1080P on the A139 Pro? I see the chart on page 2 listing Maximum but not Normal and High. Right now, I have mine on "Normal" but wonder what bitrate difference may be between Normal --> High --- Maximum

https://dashcamtalk.com/forum/threads/a139-pro-test-review-pp.48049/page-2

View attachment 72582

Sorry, I don't own the A139 Pro, so I'm really not familiar with some of the finer points of the camera's functionality and so I'm not the right person to ask.

 

[Nigel]

I have another question (sorry). Trying to learn this camera. Do you by chance know the difference in Bitrate for Normal and High with a 3 Channel 1600P 2k / 1080P / 1080P on the A139 Pro? I see the chart on page 2 listing Maximum but not Normal and High. Right now, I have mine on "Normal" but wonder what bitrate difference may be between Normal --> High --- Maximum

In 3 channel configuration, I recommend using Maximum bitrate at all times, unless you really need your memory card to last longer between overwrites. The bitrate used for Maximum with 3 channels is not particularly high for 4K resolution. If you want to make a movie with the A139 Pro, I recommend temporarily disconnecting the interior, or even both remote cameras, then you get fantastic image quality. With three channels you do loose a bit of detail even at Maximum bitrate.

 

[Nigel]

I looked up DOL-HDR. It says this is best for slow moving objects and Clear HDR for fast moving? Wouldn't you want ClearHDR for fast paced cars and license plates?

DOL HDR or Clear HDR: Which is Better for STARVIS 2 Dashcams? - VIOFO Official Website

DOL HDR or Clear HDR: Which is Better for STARVIS 2 Dashcams?

viofo.com

Clear HDR is best for movie making, DOL-HDR is best for number plate reading. Slow and fast don't really affect the decision.

Your link is an interesting read, but as with almost everything written about DOL-HDR and Clear HDR, even by Sony themselves, it is fundamentally inaccurate!

If we start at the beginning, with this quote from Viofo's web page:

Sony's official definitions of the two features, DOL HDR and Clear HDR, are as follows.

DOL HDR​

When the digital-overlap (DOL) HDR feature is on, the image sensor captures two images in succession:

Viofo are correct that Sony has made that statement, it comes from here. That seems as official as you can get.

There is a reason that Viofo have clearly stated that this is "Sony's official definition", instead of just using the Sony text on the Viofo website. The reason is that it is incorrect, the O in DOL stands for Overlapped, as in the two exposures are collected simultaneously, definitely not in succession!

Sony then continue with:

However, this method involves a slight time lapse between the two shots and this can cause some artifacts, such as a blurred outline and chromatic aberration, if the target is in fast motion.

This is also wrong, there is no time lapse because the exposures are simultaneous, and I can't see any possibility of DOL-HDR producing chromatic aberration on a Starvis 2 image sensor. Also, we do not see chromatic aberration in our Viofo dashcam videos when using DOL-HDR. Sony do clearly show an example of chromatic aberration on their web page, in the image labeled "With DOL HDR", which is very convincing, but we never see this as a result of movement of license plates on our Starvis 2 Viofo dashcam videos using DOL-HDR.

The Sony official description seems to have been written by someone who didn't have a clue how it works, and who created some fake images to clearly demonstrate what they wrote. This "knowledge" has then spread throughout the internet, with everyone believing it, because it can be traced back to an official and very believable source. The Viofo webpage doesn't help, but is careful to attribute the source to Sony!


Viofo do say, in their own words:

We conducted extensive video recording tests using the A139 PRO and A119 MINI 2 dash cams to evaluate these two HDR features. The results revealed that DOL HDR is superior to Clear HDR in terms of license plate clarity and image quality under low-light conditions.

That is correct, and will stay correct, however much development is carried out. Clear HDR will always produce a more motion blurred result, which is undesirable for reading number plates. In sunshine, when motion blur is not an issue, Clear HDR may become preferable, and for movie making, where some motion blur is desirable, Clear HDR may be preferable in all lighting conditions. I would like an action camera with Clear HDR, but I want my dashcam to have DOL-HDR... unless I am making road movies.

There is a significant upgrade to DOL-HDR coming in the near future, something that Clear HDR can not do, but that will need a new processor, so will not be added to the current A139 Pro.

 

[Michael23]

Hi guys 'n' gals,
Some general info on removing windscreen wiper scratches etc., etc., from your windscreen/s /any glass.

Go to eBay & search for "Cerium Oxide."
Buy a reasonable amount.... say, 500 gram?
It's cheap as....
It's much finer than rouge & is what our glass replacement Co's use.

To use...
In a clean plastic container, place a teaspoon/tablespoon or so of the CO to it & add water to make it the same consistency as "Brasso."
Using a clean micro fibre cloth or flannelette/cotton cloth,
rub ALONG the scratch/es....NOT across them.
Do the scratch/es in sections & take your time.
If the cloth dries out, just add a little more Cerium Oxide solution to it.

It will take a while but just persevere & the scratches & any dirt will be removed. (Eventually.)

To remove any leftover CO, just use a bucket of water or the hose.

ps. I forgot to mention this...hint.

To make it easier to see & keep track of your progress on removal of the scratch/es, use a WHITE BOARD MARKER on the INSIDE of the windscreen to highlight the scratch/es.

HTH.

Regards, Mike..

pps. You can even clean you spectacles/sun glasses as well. Just be careful with the plastic variety though.

 

[jsmith]

In 3 channel configuration, I recommend using Maximum bitrate at all times, unless you really need your memory card to last longer between overwrites. The bitrate used for Maximum with 3 channels is not particularly high for 4K resolution. If you want to make a movie with the A139 Pro, I recommend temporarily disconnecting the interior, or even both remote cameras, then you get fantastic image quality. With three channels you do loose a bit of detail even at Maximum bitrate.

Sorry for the silence. I have been testing settings on the A139 Pro in 3 Channel - Camera is New to me so I am Learning. I think I like 1600P 4K 30 FPS best. The 2160P 24 FPS seems to be more blurry at night due to less frames. I set the Bitrate to High. We had some warmer weather this week (22-24C), and it felt like on Maximum Quality, the A139 got Hot to the Touch so I dialed back the quality. High seems fine.

Right now I am testing with CPL filter as I think it is best with it on. I get a rainbow a bit due to tint in the daytime, but not a problem. It seems to help with nighttime reflection some.

The starburst issue is likely scratches (@Nigel and @Michael23 ) , so I'll take that under advisement. I'll have to see if I'm comfortable doing any of the processes. I don't want to mess up my glass.

With Michael's method, what motion would you go in to remove scratches? I guess not a circular motion?

 

[Nigel]

With Michael's method, what motion would you go in to remove scratches? I guess not a circular motion?

The scratches follow the path of the wipers, which is curved, so I think you would need circular.

As Michael said, Cerium Oxide is normally very fine, so you don't need to worry about adding scratches, it should probably end up better than new if you put enough effort in, but it will take a lot of effort, so I don't recommend starting if you are reasonably happy anyway.

I think I like 1600P 4K 30 FPS best.

Yes, if you have reduced bitrate then that is definitely best, you get more detail per pixel because there are less pixels, but the same bitrate.

 

[Michael23]

To "Jsmith" & "Nigel".....

I wrote the instructions in my post...

To use...
In a clean plastic container, place a teaspoon/tablespoon or so of the CO to it & add water to make it the same consistency as "Brasso."(eg; Thickish soup.)
Using a clean micro fibre cloth or flannelette/cotton cloth,
rub ALONG the scratch/es....NOT across them.
Do the scratch/es in sections & take your time.
If the cloth dries out, just add a little more Cerium Oxide solution to it.

Do NOT rub across the scratches.

O.K.?

ps. & don't forget the white board marker on the inside of the windscreen.

 

[Nigel]

Do NOT rub across the scratches.

The scratches follow the path of the wiper blades, a curved path, so if you are going to follow the advice to rub along and not across them, then you will have to adjust your angle as you follow along the scratches. For a perfect result, this is what you should do. Personally, I wouldn't bother for light scratching, I would just do a normal circular polishing motion, which will be correct 50% of the time whatever the angle, which is much better than being wrong.

Rubbing across the scratches will round the edges of the scratches instead of removing them, which for a perfect result is not desirable, but I think it is the edges that cause most of the starburst, so you will make an improvement a lot faster if you do rub across the scratches.

My suggestion is that you start by polishing a small bit of glass directly in front of the camera lens, then you are not risking causing any problems for driving. I am sure you will improve the video image more than you damage it, and if you end up with a good result then you can think about doing the rest, and improving the view for the driver's eyes too. If you only do a small section in front of the camera, then it will be a lot easier to rub along the scratch lines keeping the correct angle, and by not doing the bottom of the image, you will be able to see how much improvement you have made.

Don't over do it, the windscreen is laminated glass, the outer layer is not very thick. The scratches should be a tiny amount of the glass thickness though, so can be completely removed. Don't press too hard, don't get the glass too hot from the rubbing, and don't be surprised if it takes a long time to have much effect. Also remember that as soon as you use the wipers again, the scratches will start to come back, so there is little point in achieving perfection, you only need to improve things.

Interested to see how you get on, I normally give my glass a light polish once a year, so the scratches never build up very much and it doesn't take much effort.