My DIY $6.45 CPL filer for my A119

RCPilot

RCPilot

Active Member
Joined
Oct 7, 2016
Messages
85
Reaction score
103
Location
California
Country
United States
Dash Cam
Street Guardian SG9663DC Front / Rear
This isn't really specific to the A119. A while back I made a similar filter for my Mobius cam.

The good news is that the filter works quite well at significantly reducing windshield reflection. The bad news is that there is vignette even after I ground away the CPL lens holder to make it shorter. I'm going to disassemble the CPL lens again, put some double sided tape around my A119 lens housing, and stick the plastic CPL lens directly to the double sided tape. That will eliminate the vignette. Should hold up until a CPL filter made for the camera comes out. (Or until I get my 3D printer for Christmas and print myself a low profile lens holder.)

In the video you can see how when I rotate the cam how much reflection is eliminated from the iPhone screen on my desk. My windshield was dirty on the video driving with the DIY CPL so you see some specs on the video. It really cut down the reflections a lot. Doesn't seem to really darken the video either. Still have to see what it does at night.

I got this filter from Banggood, product ID # 1047861, 5 In1 2X Zoom Telephoto Macro Wide Fish Eye CPL Lens With Clip For iPhone 6/6s Plus Samsung Xiaomi Huawei". It was the cheapest thing I could find that had a CPL I could cannibalize. I found sheets of the polarized film but the sheets were more expensive than this $6.45 kit.


CLP0.jpg CPL1.jpg CPL2.jpg CPL3.jpg CPL4.jpg
 
Here is video after sticking the CPL filter directly to the dashcam without the lens holder. No more vignette. (You have to make sure the lens is rotated correctly to eliminate the glare before you stick it on. You can't just stick the filter on in any random orientation.)

 
Good solution. You might want to post it to the DIY forum as well (or ask, DashCamMan to move this one there) as it will complement some other solutions.
 
I was just thinking the same thing, with the CPL from: https://www.ebay.co.uk/itm/282214318504
I see this is the same as yours, here:
Screen Shot 2016-10-27 at 11.16.50.png Screen Shot 2016-10-27 at 11.17.51.png

I calculate, from testing, anything much more than 2mm forward of the edge of the lens housing (which is 16mm across) will be visible so the bare glass CPL would need to be attached with a small distance from the lens surround as this is just short of the enclosure within which it moves left and right. I have some 19mm self-adhesive rubber washers, 1.5mm thick which don't show when attached to the lens housing. Plan is to select correct orientation, stick the bare glass CPL to the suitable altered washer front (top and bottom of washer sliced off 1.5mm so as not to foul lens surround enclosure), then use self-adhesive washer backing to stick to lens housing.

Washers are M14 size, as here: http://abouttownbolts.co.uk/product...backed-choose-size-m2-to-m24-choose-quantity/
Or here: https://www.ebay.co.uk/itm/251120204267I bought them years ago for another project.

It is likely some of us with non-GPS will not be able to fit the Viofo CPL, due to the proximity of the original lens housing to the screen Screen Shot 2016-10-23 at 21.24.10.png
Mine is about 4mm from the screen. I guess DIY fixes are what we must do.
 
Last edited:
@DavidUK - I didn't go with eBay for the filter kit because without reviews I didn't know what I would get. I picked one from Banggood that had a good rating on the reviews.

I'm pretty happy with the cheap plastic CPL filter from Banggood as a temporary solution. Below is another video with clips during day and night. Night has a couple extra reflections but nothing bad. Doesn't seem to really impact night quality significantly. Going to leave it on my cam until I print a 3D holder for a CPL lens or until Viofo or someone else comes out with a good quality snap on filter.

 
@RCPilot - there are dozens of the same "kits" of mobile phone filters that I'm assuming they're all the same, from the same source. The one I've ordered says the filters are glass, not plastic, but I expect the CPL will be the same as yours, as Banggood's ad says the same. Have you tried scratching the lens on its edge with a needle to check it IS plastic?

GGS make a glass CPL in 16mm (same diameter as lens surround) which could be better:
https://www.ebay.co.uk/itm/111441170972http://www.photogearetc.com/magneti...hood-uv-filter-and-polarizing-cpl-filter.html
NOTE the eBay seller is in CA so cheap for you to order and have a play? This may be a better long-term solution as GGS rings a bell in the photographic arena and so it may be of decent quality... and glass!
For your printed CPL holder, are you going to attach it with tape, or maybe blu-tack? Trouble is, the outer ring of any holder is going to cause vignetting if more than 2mm-ish from the lens front.
 
@niko - thanks, that looks good! I thought of magnets but didn't know if there would be some component inside the camera or lens which might be affected by the magnetic field?
 
Small magnets I have used has no affect on dashcam lens / video.
 
DavidUK said:
@RCPilot - there are dozens of the same "kits" of mobile phone filters that I'm assuming they're all the same, from the same source. The one I've ordered says the filters are glass, not plastic, but I expect the CPL will be the same as yours, as Banggood's ad says the same. Have you tried scratching the lens on its edge with a needle to check it IS plastic?

GGS make a glass CPL in 16mm (same diameter as lens surround) which could be better:
https://www.ebay.co.uk/itm/111441170972http://www.photogearetc.com/magneti...hood-uv-filter-and-polarizing-cpl-filter.html
NOTE the eBay seller is in CA so cheap for you to order and have a play? This may be a better long-term solution as GGS rings a bell in the photographic arena and so it may be of decent quality... and glass!
For your printed CPL holder, are you going to attach it with tape, or maybe blu-tack? Trouble is, the outer ring of any holder is going to cause vignetting if more than 2mm-ish from the lens front.
Click to expand...

Unfortunately the CPL filter in my kit was just a circular piece of plastic that was pressed and held against a piece of glass with the lens holder. For $6 I wasn't expecting much.

BTW, I ordered the CPL filter from eBay on the USA eBay site that you found. Thanks for the link!

I just saw the post from @niko. He has a great post on making a slim magnetic CPL filter. It's simple and elegant. I'm going to go with his design instead of spending time making a 3D printed holder.

niko said:
You may consider one of my CPL DIY solutions to use on A119 ?

https://dashcamtalk.com/forum/threads/magnetic-cpl-lens-filter-for-street-guardian-sg9665gc.10942/
Click to expand...

Thank you @niko for sharing your link. That is an EXCELLENT post! I think you have the best solution for a CPL filter for the A119.

The A119 lens not only rotates vertically, but also horizontally, so a little extra care and planning needs to take place if one needs to maintain the ability to rotate the lens horizontally. My camera is mounted dead center on my windshield so I'm only concerned about being able adjust the lens vertically. The A119 lens housing is about 16mm. The outer housing the lens rotates inside of is about 20mm. I think something like an 18mm filter would work best with about a 1mm metal ring around the lens. That would make the diameter of lens and ring 20mm and a perfect size for a couple of small neodymium magnets to hold in place as done with in Niko's holder.

To black out the magnets and ring around the lens you can use one of these pens. Unlike a Sharpie pen or magic marker, it will not come off as it is more like paint. The pens are used to touch up scratches on guns and rifles.

Birchwood Casey Super Black Touch Up Pen Flat
Link: https://www.amazon.com/gp/B00BGH0Y0W
 
Last edited:
Of course, we don't know if the Viofo CPL will fit older A119 models yet, or the price, or whether the glass filter itself could be utilised in a DIY solution if the Viofo CPL mount it too big and so hits the windscreen in certain applications?
 
The people that got the sample units have the old lens housing, it's a good fit on the new lens housing obviously but still easily adaptable to the old model
 
RCPilot said:
Unfortunately the CPL filter in my kit was just a circular piece of plastic that was pressed and held against a piece of glass with the lens holder. For $6 I wasn't expecting much.

BTW, I ordered the CPL filter from eBay on the USA eBay site that you found. Thanks for the link!

I just saw the post from @niko. He has a great post on making a slim magnetic CPL filter. It's simple and elegant. I'm going to go with his design instead of spending time making a 3D printed holder.



Thank you @niko for sharing your link. That is an EXCELLENT post! I think you have the best solution for a CPL filter for the A119.

The A119 lens not only rotates vertically, but also horizontally, so a little extra care and planning needs to take place if one needs to maintain the ability to rotate the lens horizontally. My camera is mounted dead center on my windshield so I'm only concerned about being able adjust the lens vertically. The A119 lens housing is about 16mm. The outer housing the lens rotates inside of is about 20mm. I think something like an 18mm filter would work best with about a 1mm metal ring around the lens. That would make the diameter of lens and ring 20mm and a perfect size for a couple of small neodymium magnets to hold in place as done with in Niko's holder.

To black out the magnets and ring around the lens you can use one of these pens. Unlike a Sharpie pen or magic marker, it will not come off as it is more like paint. The pens are used to touch up scratches on guns and rifles.

Birchwood Casey Super Black Touch Up Pen Flat
Link: https://www.amazon.com/gp/B00BGH0Y0W
Click to expand...

Glad you may find some of my DIY CPL ideas to be used on A119. After you finish your project you may share results here or in DIY section.
 
@jokiin - I'm just a little worried about the corner dimension of the CPL housing, for those of us who don't have the GPS mount.

Remember?... Screen Shot 2016-10-29 at 11.06.14.png

I have maybe 3-4mm at this corner, from the screen.
 
My eBay set has arrived and as RCPilot says, it's just a piece of plastic film behind a piece of clear glass.
AND... it's not a CPL, it's a linear polariser, as per this test, as it passes light both sides when looked through at a mirror:

"Hold it in front of a mirror, and try to see if you can see light going through the polarizer, bouncing off the mirror, and coming back through the polarizer again. If the "camera side" (male threads) is against the mirror, the circular polarizer won't pass light, though it will pass some light if you flip it so the camera side is away from the mirror. A linear polarizer will pass the same amount of light regardless of which way it's flipped."

Back to the drawing board?

@RCPilot - have you done this test with your plastic "CPL"? Did the GGS one arrive yet?
 
Linear polarizer should work with a dash cam no problem. My first DIY used an old pair of clip on sunglasses as a source and they are linear and worked just fine. CPL is necessary for SLRs due to the way the auto focus works but since dashcams are fixed focus are not necessary.

Whether the plastic film is polarized or not is a different matter but some simple testing should be able to determine that.
 
Oops, forgot to tag @DavidUK in my last post so he would see it. ;)
 
I did try it in front of my eye, looking at the reflections in the glass of my mobile phone and it did reduce glare when revolved.
And I was aware it may work, and @Nigel had reckoned so too, here: https://dashcamtalk.com/forum/threads/cpl-status.20524/page-8#post-289825

But I don't think @viofo ever answered my question, here: https://dashcamtalk.com/forum/threads/cpl-status.20524/page-8#post-289819
...regarding if the Viofo CPL needs to be a CPL, or if a linear filter will give identical results?
I ask as I believe an SLR may have light metering issues related to the type of polariser, as well as auto focus ones? But I've no idea what light metering, if any, goes on inside the A119.
 
DavidUK said:
...
...regarding if the Viofo CPL needs to be a CPL, or if a linear filter will give identical results?...
Click to expand...
@viofo will have to respond to that but since there is not A/F involved it should.

DavidUK said:
...I ask as I believe an SLR may have light metering issues related to the type of polariser, as well as auto focus ones?...
Click to expand...
To the best of my knowledge it's only an A/F concern, not exposure, with SLRs but I would not make any large wagers on that.
 
You must log in or register to reply here.
Back
Top