How to adjust the cpl filter efficiently?

[tchavei]

So, I finally wired my A139 Pro in my car (dual channel).

During the weeks I tested the cam on the bench, I found a neat way of adjusting the cpl filter: point the dashcam to a LCD TV and it will be mostly washed out. Slowly rotate the cpl filter a few degree from the white alignment mark until the TV picture shows perfectly.

Unfortunately I forgot about it and removed the cpl filter. Now the camera is in the car and I dont want to find a TV on the street to calibrate the cpl filter.

Any quick suggestions?

Thx

 

[DT MI]

First, using a TV (or phone, tablet, laptop, monitor, etc.) to orient the CPL is not the best way because it's dependent on how the polarizing layer of the screen is oriented. Different devices have different orientations. In my house I've found device screens with 3 different orientations.

The method I use is infallible and only needs a sheet of paper - https://dashcamtalk.com/forum/threa...nt-how-to-adjust-diy.15022/page-2#post-197505

 

[tchavei]

First, using a TV (or phone, tablet, laptop, monitor, etc.) to orient the CPL is not the best way because it's dependent on how the polarizing layer of the screen is oriented. Different devices have different orientations. In my house I've found device screens with 3 different orientations.

The method I use is infallible and only needs a sheet of paper - https://dashcamtalk.com/forum/threa...nt-how-to-adjust-diy.15022/page-2#post-197505

Woah. Didn't know that method. Will try tomorrow. The reflections I'm having aren't terrible but would like it a little better.

On the other hand I notice I more... I don't know, saturated image when comparing to the back camera. I wonder if it's because of the cpl filter on the windshield

 

[Dashmellow]

My favorite method is to adjust in real time outdoors (usually a parking lot) using a small external AV monitor (depending on the camera), the LCD screen built into the camera or a smart phone via WiFi.

 

[DT MI]

...I notice I more... I don't know, saturated image when comparing to the back camera. I wonder if it's because of the cpl filter on the windshield

Yes, a polarizing filter will increase saturation. Many photographers use them for that purpose.

 

[tchavei]

Btw, here a snapshot. The reflections aren't very bad but if it can be improved, the better. Notice the different saturation between front and back

My favorite method is to adjust in real time outdoors (usually a parking lot) using a small external AV monitor (depending on the camera), the LCD screen built into the camera or a smart phone via WiFi.

Oh great. I'll check it out. Thank you!

 

[Dashmellow]

Btw, here a snapshot. The reflections aren't very bad but if it can be improved, the better. Notice the different saturation between front and back

Those don't look too bad at all.

One thing to consider would be a black dash mat. They can work better than a CPL (and with a CPL they are REALLY effective). You can buy or make one for both the front and rear. (Although right hand drive versions can be a little hard to find.)

See this link for some examples.

https://dashcamtalk.com/forum/threads/strange-rainbows-in-your-dash-cam-videos.44714/post-547467

 

[tchavei]

Those don't look too bad at all.

One thing to consider would be a black dash mat. They can work better than a CPL (and with a CPL they are REALLY effective). You can buy or make one for both the front and rear. (Although right hand drive versions can be a little hard to find.)

See this link for some examples.

https://dashcamtalk.com/forum/threads/strange-rainbows-in-your-dash-cam-videos.44714/post-547467

Thx. It isn't that bad but that was just with putting the cpl filter on. No adjustments yet. I'll try to tweak it a little bit. The matt is interesting albeit with our weather, it might heat up the car even more

 

[kamkar]

I use the live preview on my phone, throw a piece of paper on the front of my dashboard and turn the CPL until it its reflection is as faded as it will get.
My dash mat which i also have, well as i drive a cheap little car, nothing factory made to fit my car, so i got some black cloth like used my photographers and theaters for background, and cut that up to cover my dashboard.

 

[tchavei]

I'll try that too albeit today when I was looking at my phone, the sun was so bright I could barely distinguish what I was seeing on the screen.

Maybe a tablet is in order

 

[kamkar]

Maybe do it at night, the cabin light should be file to light up a piece of paper on the dash so you can see its reflection in the windscreen.

With old tired eyes like me, things are not easier