To anyone who wants a CPL filter for the rear camera of the A139!!

Looks good :)

Facing in that direction, it will be reducing glare off the side windows?!
 
Very clean! Too bad I haven't noticed it before (or you haven't posted it a bit sooner :ROFLMAO: ), I took a bit different approach and used this.

EDIT: Oh, 20$. Ok, I regret nothing. :D
 
Looks good :)

Facing in that direction, it will be reducing glare off the side windows?!
Sorry I haven't tried recording videos from the back facing to the interior with CPL on.
But I have no glare problem without CPL.
So maybe different cars have different result?:rolleyes:2.jpg

Direct to the sun to the rear windshield with Thinkware CPL on.
1.jpg
 
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Very clean! Too bad I haven't noticed it before (or you haven't posted it a bit sooner :ROFLMAO: ), I took a bit different approach and used this.

EDIT: Oh, 20$. Ok, I regret nothing. :D
Yeah, I know $20 for a small CPL is like crazy.....o_O
I was thinking the same thing (Polarized Film), may I know how it looks?
Thanks.
 
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I simply re-used an old dashcam CPL (from my SG9665GC, but any circular CPL could be used). It's held in place by a couple of dabs of UV glue. This was a bit tricky to install within the car since the camera is not removable from its mount.

If I like the result after a few weeks of testing I'll dismount the camera and re-affix the CPL with a tidier glue edge, then re-mount the camera on the rear screen.

1652888400778.png
 
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Yeah, I know $20 for a small CPL is like crazy.....o_O
I was thinking the same thing (Polarized Film), may I know how it looks?
Thanks.

You want crazy, how about $98.80 USD for a Hoya HD3 CPL? !! :eek:

I use an original 37mm version of the Hoya HD CPL on one of my dash cams. Fortunately I only paid $18.00 for mine after stumbling across it online for that price but they sold for about $40.00 at the time.

There is simply nothing else like it on the market that offers the same optical performance. The main feature is that it allows one full stop more light transmission than any other CPL filter available so there is far less penalty in terms of motion blur or exposure. Most CPL filters lose two or more ƒ stops of light transmission but the Hoya HD loses only one and 1/6 stop of light. It also happens to outperform other CPLs in terms of contrast, color and acuity plus has an ultra-hard Nano-coating that makes the filter especially durable, hydrophobic and fingerprint resistant. Worth every penny! Hoya, the world's largest maker of optical glass produces a whole line of high performance CPL filters.

I too use UV curing cement to attach filters like this to my dash cams. UV cement provides a fast secure bond that is safe around optical surfaces and can be removed fairly easily when the time comes.
 
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I simply re-used an old dashcam CPL (from my SG9665GC, but any circular CPL could be used). It's held in place by a couple of dabs of UV glue. This was a bit tricky to install within the car since the camera is not removable from its mount.

If I like the result after a few weeks of testing I'll dismount the camera and re-affix the CPL with a tidier glue edge, then re-mount the camera on the rear screen.

View attachment 60547
My DIY CPL for the A139 rear camera has not worked out very well because I'm getting extensive haze or fogging around the CPL. There is a small air gap - the UV cement is not a complete ring - but perhaps it needs more air?

This is happening in the middle of summer when it's fairly dry. I expect the fogging may become much worse into autumn and winter as my car suffers from condensation more than most.

1659090783434.png

Whilst I could try to fix this, my preference is to run the camera without the CPL for better low light performance so I will be removing the CPL.

My reason for trying a CPL was to see clearly through the windscreen of cars behind me, however the A139 rear camera doesn't really have enough detail or clarity to do this unless at very close range. I'll look at installing a CPL on a rear-facing 4K/telephoto camera instead which will have a closer view of the car behind.
 
the UV cement is not a complete ring - but perhaps it needs more air?
I’ve used square CPL’s stuck on with small bits of black 3M pad in the corners, so plenty of ventilation, seems to work fine.
 
My DIY CPL for the A139 rear camera has not worked out very well because I'm getting extensive haze or fogging around the CPL. There is a small air gap - the UV cement is not a complete ring - but perhaps it needs more air?

View attachment 61220
I removed the CPL yesterday and found that the fogging is trapped between the two layers of the CPL, so it seems to be a CPL failure rather than a ventilation issue.
 
I removed the CPL yesterday and found that the fogging is trapped between the two layers of the CPL, so it seems to be a CPL failure rather than a ventilation issue.
Why does the CPL have two layers?

Technically the C bit is a seperate layer to the PL bit, but they are just coatings on a single layer of glass/plastic.
Where you possibly supposed to remove one of them - a protective layer for shipping?
Edit: Looking at your image, maybe the UV cement has split the two layers of glass? But I don't know why there are two layers...
 
Why does the CPL have two layers?

Technically the C bit is a seperate layer to the PL bit, but they are just coatings on a single layer of glass/plastic.
Where you possibly supposed to remove one of them - a protective layer for shipping?
Edit: Looking at your image, maybe the UV cement has split the two layers of glass? But I don't know why there are two layers...
I don't know why it has two layers, but it's not a protective layer for shipping. The Viofo CPL has similar construction.

1661257568917.png
 
Earlier versions of the Street Guardian CPL had four layers of glass which were prone to delamination in hot conditions.

Typical of Street Guardian crisis management whenever their cameras exhibit an issue, they claim to have not have heard of the problem. Then they finally admit the problem but claim that it is exceedingly rare and make each customer feel like an outlier but provide prompt customer service and replacement . Meanwhile, more and more reports of the issue start flooding in. This was a widespread issue that required a different CPL glass in later versions. Eventually, SG will quietly fix the problem and go back to acting like there was never really an issue in the first place. Happened to me on multiple occasions with their products and accessories. In this case, I had to have my Street Guardian CPL replaced twice due to delamination of the glass layers. I never really experienced a fogged filter; instead I had birefringence rainbows and moire patterns between the delaminating glass layers.

 
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The Viofo CPL has similar construction.

The Viofo filter was identical to the Street Guardian CPL. Both companies collaborated behind the scenes to produce the filter to save costs. Ever notice that they also often use the identical housings and other components?
 
The Viofo filter was identical to the Street Guardian CPL. Both companies collaborated behind the scenes to produce the filter to save costs. Ever notice that they also often use the identical housings and other components?
Almost identical. I found that the plastic frames for the A129 Pro and the SG9663DR CPL were a fraction of a mm different. I can't tell which is which by eye.

But in general yes, I was aware that they shared a number of resources to make housings, CPL filters, hardwire kits etc.
 
Almost identical. I found that the plastic frames for the A129 Pro and the SG9663DR CPL were a fraction of a mm different. I can't tell which is which by eye.

But in general yes, I was aware that they shared a number of resources to make housings, CPL filters, hardwire kits etc.

The original version of the CPL was identical for both companies but were later modified slightly. The original SG/Viofo filters didn't hold securely on the lens module. Later models added a slot to the lens module that the new version of the CPL frame could click into with a protrusion that matched the slot. There may have been other customizations.
 
I don't know why it has two layers, but it's not a protective layer for shipping. The Viofo CPL has similar construction.

View attachment 61582
CPL removes polarized (reflected) light and then lets the light oscillate circularly in all planes - this affects the accuracy of exposure and possibly focus (not sure). While the PL filter works the same way, the light behind it can have some negative effect on the lens. That's why the multiple layers .. I'm writing this in very layman's terms, I recommend Wikipedia or another description of the CPL filter
 
I don't know why it has two layers, but it's not a protective layer for shipping. The Viofo CPL has similar construction.

The CPL had polarizing film sandwiched between two layers of optical quality glass. The polarizing film is a dichroic layer, sometimes called “pola foil,” made from polyvinyl alcohol (PVA) plastic and it is very thin. The film is stretched during manufacturing, forcing the molecules in the plastic to line up in long parallel chains with tiny gaps between them like the bars of a jail cell, or a picket fence. These chains are invisible to the naked eye. This stretched polymer is then dipped in a solution of iodine, and the iodine molecules attach themselves to the polymer chains. The resulting structure allows the pola foil to absorb light waves that are parallel to the long chains while allowing waves that are perpendicular to pass through unaltered thus blocking light waves coming from other angles.

The name "polarizer" comes from the fact that it was invented in 1929 and then revised in 1938 to its current form by Polaroid the company that later invented the Polaroid camera. Polarizing filters are more or less made the same way they were 85 years ago with some enhancements and improvements by companies like HOYA in Japan.
 
The CPL had polarizing film sandwiched between two layers of optical quality glass. The polarizing film is a dichroic layer, sometimes called “pola foil,” made from polyvinyl alcohol (PVA) plastic and it is very thin. The film is stretched during manufacturing, forcing the molecules in the plastic to line up in long parallel chains with tiny gaps between them like the bars of a jail cell, or a picket fence. These chains are invisible to the naked eye. This stretched polymer is then dipped in a solution of iodine, and the iodine molecules attach themselves to the polymer chains. The resulting structure allows the pola foil to absorb light waves that are parallel to the long chains while allowing waves that are perpendicular to pass through unaltered thus blocking light waves coming from other angles.

The name "polarizer" comes from the fact that it was invented in 1929 and then revised in 1938 to its current form by Polaroid the company that later invented the Polaroid camera. Polarizing filters are more or less made the same way they were 85 years ago with some enhancements and improvements by companies like HOYA in Japan.
You describe a PL filter but not a CPL

- a circular filter (CPL) has an auxiliary film that polarizes the light circularly after passing through the polarizing filter, so that it is more similar to the original unpolarized light for further processing in the camera (however, with circularly polarized light the resulting electrical intensity vector oscillates in a circle, not randomly as with unpolarized light).
The use of a linear (PL) filter in a camera can have a negative effect on the quality of autofocus or exposure metering.
 
Well, so what. I was answering TonyM's question about why the filter has two layers and otherwise it is merely the history and basics of how polarizers work, how they were invented and where the name comes from. As I mentioned, later companies enhanced and improved on Edwin Land's invention. A circular polarizer is essentially the same principle using a quarter wave plate where the axis is 45 degrees and they are made the same way.
 
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