Running polarizers at night in reviews

Vortex Radar

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So when doing dashcam reviews, I generally like to run CPL's day to day, but for testing and reviews I normally like to remove the polarizers to maximize video quality for license plate zoom-ins and whatnot. They also block some light so they make night time video look worse, forcing the dashcam to boost their exposure and raise the noise level. I also expect slower shutter speeds even during the daytime, especially in the shade (though I haven't done a direct head to head to confirm, not to mention this would likely vary between dashcams) and so all this would affect how much motion blur you'll get with passing cars and how well you can freeze frame and clearly read plates.

That said, I wonder how common it is to run polarizers and if it would make sense to review dashcams with them. I've got some nighttime footage saved running with a CPL, but I wonder if it'd make sense go out and get some footage without it too for the sake of the review. I think it'd make sense, but I think it's starting to get complicated collecting test clips with and without a CPL, with HDR on and off, on super dark roads and on well lit roads, and then wanting to go over all that footage and do a clear comparison on how things look in different conditions.

The easiest thing to do is to park in a parking lot and get footage with and without the CPL, with HDR on and off, and look at the differences that way. I'd rather test and compare while moving, but that's harder to do directly since things will always look a little different from one drive to another.

So anyways, I wanted to hear your thoughts regarding using polarizers for dashcam tests and reviews, especially at night.
 
3 minute clips with and without a CPL, day and then night. Same for HDR, day and night and then Day + CPL + HDR on and off and so forth. Links to RAW files for each video.
 
Ideally you would like to have two units when doing HDR on/off and CPL on/off as it's easier to compare looking at the same stretch of the road at the same time.
 
3 minute clips with and without a CPL, day and then night. Same for HDR, day and night and then Day + CPL + HDR on and off and so forth. Links to RAW files for each video.

Ideally you would like to have two units when doing HDR on/off and CPL on/off as it's easier to compare looking at the same stretch of the road at the same time.
Oh for sure, there's a lot of things I'd like to do in an ideal world too, but then it leads to dashcam reviews literally taking an entire month. It's hard to test and compare lots of dashcams and to not get overwhelmed and burned out as a reviewer when you try to test everything under the sun, lol.

So practically speaking, for the sake of simplicity, is there value in considering nighttime footage when shot with a polarizer?
 
Yes, of course. IMO a review wouldn't be complete without nighttime footage without and with a CPL. I'd want to share as many different examples as possible, thus enabling a prospective buyer that's relying on one's review to make an informed decision. Let them see it for themselves than just saying it's good or bad.

All possible examples don't need to be shared at the time of publishing the review, keep adding as you continue using the dashcam.
 
hm, I've got a T130 as well. If the video from that dashcam's front cam is comparable, I could always run those two together to do a test with/without a CPL, with HDR on/off, etc. without having to spring for a second A139, lol.
 
If you are comparing two cameras, just make sure that both either have or both don't have a CPL, so that it is a fair comparison.

I think most of us use CPLs with Viofo dashcams night and day, for the front channel, most don't use them for the rear, although some people do so that they can see through the windscreen of the car behind to see the driver using their phone!

Using a CPL should roughly double the motion blur, so it is not good for reading plates, but having cloud instead of sun will make much more difference, as will having LED streetlights instead of sodium streetlights, or no streetlights, so leaving it on doesn't really matter, and it does tend to make differences between cameras more obvious.

Having too much data just confuses things!
 
hm, I've got a T130 as well. If the video from that dashcam's front cam is comparable, I could always run those two together to do a test with/without a CPL, with HDR on/off, etc. without having to spring for a second A139, lol.
They should be very similar, but in reality, the T130 is a cheaper camera than the A139, and there are differences that show up - voice quality is obvious.
 
...So practically speaking, for the sake of simplicity, is there value in considering nighttime footage when shot with a polarizer?
Given that the purpose of doing reviews is not to make it easier for the reviewer but to provide useful information for potential buyers IMO it would benefit the most people by doing night testing with the polarizer. I seriously doubt that the 'average' dash cam owner that uses a polarizer would remove them for nighttime driving and then put them back on during the day - just a bit too much hassle unless it were as easy as 'flipping a switch'.

In my case I always have a polarizer on both front and rear cameras, so tests/reviews without are of no practical benefit to me.
 
If you are comparing two cameras, just make sure that both either have or both don't have a CPL, so that it is a fair comparison.

I think most of us use CPLs with Viofo dashcams night and day, for the front channel, most don't use them for the rear, although some people do so that they can see through the windscreen of the car behind to see the driver using their phone!

Using a CPL should roughly double the motion blur, so it is not good for reading plates, but having cloud instead of sun will make much more difference, as will having LED streetlights instead of sodium streetlights, or no streetlights, so leaving it on doesn't really matter, and it does tend to make differences between cameras more obvious.

Having too much data just confuses things!
Nooooo kidding, lol, not to mention even after looking at dozens of clips across multiple cameras, I still find that sometimes dashcam A captures a plate best, sometimes dashcam B, sometimes dashcam C... It's hard enough as it is to give a simple and clear answer as it is without adding a bunch of additional variables. :D

That said, I just mounted the T130 next to my A139. One has a polarizer, one doesn't. I purely wanna do some head-to-head comparison first with and without the CPL. I also noticed the T130 does WDR while the A139 does HDR so I guess for HDR testing, I'll do T130 without no CPL and no WDR. Then I can do A139 with no CPL and with HDR on.

It's raining now so I can't go out yet to capture some daytime test footage, but at least things are ready.
 
They should be very similar, but in reality, the T130 is a cheaper camera than the A139, and there are differences that show up - voice quality is obvious.
For just the front camera only and nothing else, I understand the two share the same sensor and resolution options. Are the lenses and video quality otherwise the same? I'm gonna crank both up to max bitrate and start doing some comparisons that way, primarily to test the CPL and HDR features.

For an A139 and T130 comparison, yeah then we get into differences with the voice notifications, interior cam setups, etc.
 
Given that the purpose of doing reviews is not to make it easier for the reviewer
Very true, but as a reviewer when you bite off more than you can chew, it become overwhelming and not enjoyable. So from a practical sense, I have to ensure I'm keeping everything in balance to keep the process sustainable, especially if wanting to test lots of different dashcams.
but to provide useful information for potential buyers IMO it would benefit the most people by doing night testing with the polarizer. I seriously doubt that the 'average' dash cam owner that uses a polarizer would remove them for nighttime driving and then put them back on during the day - just a bit too much hassle unless it were as easy as 'flipping a switch'.
Agreed. This also seems to vary between models.

The Viofo polarizer slides on and stays well. It's not really easy to keep taking on and off, especially given that you have to ensure that the polarizer is aligned properly every time.

The Thinkware U1000 polarizer literally sticks to the dashcam's lens so it's not designed to be removable at all.

I've got two different Blackvue polarizers, both of which are orientation locked so I don't have to worry about aligning each time. One polarizer slides onto the front. The other one slides on from the side, but it leads to some vignetting so I tend to avoid using it despite the easier mounting method. I personally do like installing it during the daytime and removing it at night given that it's relatively easy to do. If that gets old, I tend to run it more in the summer when it's light outside longer and remove it in the winter when it's still dark in the morning and afternoons.
In my case I always have a polarizer on both front and rear cameras, so tests/reviews without are of no practical benefit to me.
Totally fair. I generally run a polarizer on the front, but almost never on the rear. Hard to cover all use cases for everyone. :)
 
Are the lenses and video quality otherwise the same?
Firmware updates keep changing things, but I think you will find bitrate differences, so you may see little difference in the city, but then an obvious difference under trees in the countryside - makes it very difficult to make a proper comparison!
 
Firmware updates keep changing things, but I think you will find bitrate differences, so you may see little difference in the city, but then an obvious difference under trees in the countryside - makes it very difficult to make a proper comparison!
hmm, let's see... I've got both dashcams set to 2K30, H.265, and max bitrate.

A139 is around 23 Mbit. T130 is 25-26 Mbit.

Given that it's not identical, I may indeed need to order a second A139.

Done. Another A139 should be here tomorrow. You can never have enough dashcams... lol.
 
For best image quality I recommend H264, although there shouldn’t be much difference.

Also 2K30 , max bitrate , no WDR, with front CPL
 
So when doing dashcam reviews, I generally like to run CPL's day to day, but for testing and reviews I normally like to remove the polarizers to maximize video quality for license plate zoom-ins and whatnot. They also block some light so they make night time video look worse, forcing the dashcam to boost their exposure and raise the noise level. I also expect slower shutter speeds even during the daytime, especially in the shade (though I haven't done a direct head to head to confirm, not to mention this would likely vary between dashcams) and so all this would affect how much motion blur you'll get with passing cars and how well you can freeze frame and clearly read plates.

That said, I wonder how common it is to run polarizers and if it would make sense to review dashcams with them. I've got some nighttime footage saved running with a CPL, but I wonder if it'd make sense go out and get some footage without it too for the sake of the review. I think it'd make sense, but I think it's starting to get complicated collecting test clips with and without a CPL, with HDR on and off, on super dark roads and on well lit roads, and then wanting to go over all that footage and do a clear comparison on how things look in different conditions.

The easiest thing to do is to park in a parking lot and get footage with and without the CPL, with HDR on and off, and look at the differences that way. I'd rather test and compare while moving, but that's harder to do directly since things will always look a little different from one drive to another.

So anyways, I wanted to hear your thoughts regarding using polarizers for dashcam tests and reviews, especially at night.
Since you are bringing up head-to-head comparisons of dashcams in testing, has any of your testing shown noticeable exposure differences between front and rear dashcams with virtually all the new Blackvue model dashcams?

A very active member of this forum, @rcg530, who's also a dashcam reviewer, has completed many head-to-head comparisons by mounting both front and rear Blackvue dashcams to the front windshield.


His testing has shown that in many instances the rear dashcam (RC110F) is taking darker videos. He has reported the differences to both us consumers and to Blackvue/Pittasoft... Have you done any similar testing?
 
Since you are bringing up head-to-head comparisons of dashcams in testing, has any of your testing shown noticeable exposure differences between front and rear dashcams with virtually all the new Blackvue model dashcams?

A very active member of this forum, @rcg530, who's also a dashcam reviewer, has completed many head-to-head comparisons by mounting both front and rear Blackvue dashcams to the front windshield.


His testing has shown that in many instances the rear dashcam (RC110F) is taking darker videos. He has reported the differences to both us consumers and to Blackvue/Pittasoft... Have you done any similar testing?
Ah yeah, I've found the same to be true. I've done some testing on that in these two videos IIRC.



I've noticed the RC110 being darker, the newer Blackvues have HDR which you can't disable, the newer Blackvues removed manual control over exposure levels, and there's also sample variation between different copies of the rear dashcams too in terms of sharpness.
 
On reviewing...
Ideally one tests everything in all conditions; in fact that is the only way to know what does best and what doesn't. It is a lot of work but anything else might be misleading. One of the 'tricks' I use is to record one particular stretch of road as a standard as going almost anywhere from home needs me taking it. This lets me get comparable footage over several days as long as sky conditions and time are the same, and I can set up each day's test the night before, and swap cards/reset test parameters at the end of the day. My "test track" has full sun, shade, oncoming traffic, overtaking traffic, stores and signs, traffic lights, streetlights and no lights, low speed and medium-high speed driving. In 5-6 minutes of road I encounter all the conditions and changes that need investigation and I'm driving there anyway so only night-time footage takes extra work. 2-4 cams can be tested each day together so that in a week you can have that many thoroughly tested. Stagger the test-start days for each cam to spread out the workload. Edit and show your best vids and any anomalies you feel should be seen; the rest needs only mentioning.

On my drive home I sometimes try different settings to help optimise things like exposure more quickly, but generally I use and stay with default settings for published videos since most users are going to use their cams that way; those who might take the time to fine-tune will find their own best settings anyway. If you're good with such things set up a spreadsheet where you can list all trial settings and 'grade' them, then refer to that when recording or writing your review. Organization and standard testing routines= efficiency and best results fastest. And thank god I almost never need to test more than 2 cams together or I might go nuts!

Phil
 
Ideally one tests everything in all conditions; in fact that is the only way to know what does best and what doesn't. It isa lot of work but anything else might be misleading.
........... If you're good with such things set up a spreadsheet where you can list all trial settings and 'grade' them, then refer to that when recording or writing your review. Organization and standard testing routines= efficiency and best results fastest.


Exactly. (y) Anything less cannot be considered a comprehensive test/review.
 
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