Quick test of just received prototype CPL (Circular Polarizer/Linear ) filter for the B4k

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JeffNLasVegas

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Quick test of just received CPL (Circular Polarizer/Linear ) filter for the B4k. Properly rotating the filter will dramatically reduce the glare from direct sunlight. I own two B4ks (one for the front and one for the back windshield). In the coming week I will unmount the rear unit and place it side by side with the other b4k within the front windshield and then provide a direct comparison video between one with the CPL and the other without.

Note: the prototype is silver, but the final version is going to be black. I actually like the silver, but the black is more practical.


053F2093-97BA-44DD-A04B-08B28CBC02E8.jpeg

016D01EE-D0E9-4B57-8D75-0CDD2E7854BF.jpeg
 
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Sweet.
Really a CPL filter are a must, i use them even if i also have a DIY dashmat made of flat black cloth draped over the top of my dashboard.
 
Nice improvement to the sky, and to being able to see into other cars!
 
Needs to be black not silver...
 
Just a quick dip in the elox and the ALU will be black,,,,, or another color you like.
I am sure Blueskusea will also do that for us with the production CPL filters.
 
It will be black - the one I'm getting is.
 
Still waiting on mine, will be after the CNY holiday I'm told :whistle:

I don't think a CPL is always necessary, but sometimes they are. I get some dash reflections but you can clearly see the images I want, so nothing lost as long as the auto-exposure isn't being adversely affected ;) I'm more concerned about loss of brightness at night, low-light conditions are hard enough already. It's been said that having the lens close to the windshield helps, but in testing numerous cams both close to and far away from the glass I have not found this to be true. The best I ever had was the Mobius set far back, yet a B2W set a little further away captured more reflections, as did several other cams mounted closer :cautious:

So as far as I can tell, each case is a law unto itself and only actual testing will answer whether you need a CPL or not. I've also seen cases where they made little difference based on before-and-after vids others have posted :rolleyes: Given the minimal cost it's sure worth trying is you have reflection issues :cool:

Phil
 
SawMaster said:
Still waiting on mine, will be after the CNY holiday I'm told :whistle:

I don't think a CPL is always necessary, but sometimes they are. I get some dash reflections but you can clearly see the images I want, so nothing lost as long as the auto-exposure isn't being adversely affected ;) I'm more concerned about loss of brightness at night, low-light conditions are hard enough already. It's been said that having the lens close to the windshield helps, but in testing numerous cams both close to and far away from the glass I have not found this to be true. The best I ever had was the Mobius set far back, yet a B2W set a little further away captured more reflections, as did several other cams mounted closer :cautious:

So as far as I can tell, each case is a law unto itself and only actual testing will answer whether you need a CPL or not. I've also seen cases where they made little difference based on before-and-after vids others have posted :rolleyes: Given the minimal cost it's sure worth trying is you have reflection issues :cool:

Phil
Click to expand...
I just installed my B4K camera, which CPL filter fits it?
 
deoccultist said:
I just installed my B4K camera, which CPL filter fits it?
Click to expand...
I will send you one free from China if you PM me your shipping address and order number.
 
Only blueskyseas own filter i assume.
But not sure if these are listed for sale just yet.
 
I wish there was an aftermarket CPL for the 70mai units as well, since they seem not to be interested in making them even though they have been asked to.
 
In the old days there was a lot of CPL DIY going on, but you will have to be lucky to get one that just fit, so some creative forces are a must.
@EGS this is the CPL for the A139 camera, 21.5 mm in diameter, mounts with a friction fit to that camera.

IMG_20210310_041748.jpg
 
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kamkar said:
In the old days there was a lot of CPL DIY going on, but you will have to be lucky to get one that just fit, so some creative forces are a must.
@EGS this is the CPL for the A139 camera, 21.5 mm in diameter, mounts with a friction fit to that camera.

View attachment 55750
Click to expand...
Thanks for sharing the measurements. I will take measurements to the lens barrel of the A800s tomorrow to see if it is close to the a139. I already started one last week cutting a ring out of a 1/2 inch pvc pipe but didn't like the way it came out. Maybe I need to put a bit more time to refine it.
 
There is still the issue of FOV, if a 70mai camera use wider FOV than the A139 this filter are for, you might see some of it in the comers of the footage.
 
Any dashcam need a CPL filter, only in a few vehicles are it not so.
 
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