Best ND filters for P4P

[Tomas Wangen]

I really don't think polarzing filters are suited to drones in majority of situations.

In general including the sky with the combination of a wideangle lens and a polarizing filter is very difficult at best. However, for reducing glare (of for instance vegetation) or especially reducing reflections of water are good uses even for this combination.

 

[AIRSPACE]

I have the PolarPro ND/PL and when used right it could really enhance a shot but the difficulty of what you guys have said and having to realign the polarising regularly for best results (which isn't marked on the filter due to weight/cost?) is the reason why I just bought the regular NDs for the P4P

 

[splinetime]

Greetings, I am new to drone and aircraft operation, but have been involved in film and video production for decades. I may be misreading the conversation, but it sounds like circular polarization is not being addressed correctly. Apologies if I misunderstood.

My two cents: The reason you want to use a circular polarizer on electronic sensors is because a simple linear polarizer delivers the polarized light... well polarized! It is "in line" with the microscreen of the polarizer and can interact adversely with sensor devices because they quite often have a "linear" structure. Circular polarizers add a "Scatter" function to the lightwaves exiting the PL filter. The "polarized" light is, in effect, "de-polarized" (the scene light entering the filter is still affected as expected) but then the output is "randomized" I have used quotes wherever I'm loosely using the word in a general sense, not a pure scientifically accurate description.
Happy flying and safe shooting
Kevin L.

A couple of references:
Most detailed and accurate resource:
Understanding & Using Polarizing Filters

Other References
All about Polarizers - Linear and Circular
How a Polarizer Filter Works

from the Hoya filter website:
"How it works, Filters out Polarized Light
Polarized light is light who’s rays have been scattered due to pollution, moisture in the atmosphere and reflection. A circular polarizer filter only allows light rays that are traveling in one direction to enter the lens. This is how the Circular polarizer works it’s magic.

The Hoya Circular Polarizers are actually made up of a piece of high quality optical glass followed by a linear polarizing film, this film, which is actually a micro screen, filters out the scattered light rays and only passes light moving in one linear direction. Modern camera meters and auto focus systems can have problems reading light moving linearly. A quarter wave plate is added behind the polarizing film to send the light into the lens in a circular pattern. This circularly polarized light will not interfere with any camera metering or auto focus systems.

Keep in mind that when any kind of light is filtered out, polarized or not, there is a reduction in exposure.

 

[Basspig]

I'm shopping for a polarizing lens right now. I've used them for ground photography and love the deep, saturated blue skies and how they cut the haze on humid days.
But my concern is finding one that isn't optically mediocre. I don't want to lose resolution in the process.
Who makes a good polarizing filter for the P4P?

 

[msinger]

Who makes a good polarizing filter for the P4P?

Here are some of the brands that consistently have good reviews:

• Freewell
• PGYTECH
• PolarPro
• SANDMARC
• SKYREAT

You can find a list of filters offered by these companies here.

 

[ChrisLX200]

I bought the Polar Pro Cinema filters. Screwed one on and had a devil of a job to get it off again. Had to make a tool to grip it (impossible with fingers alone). And no, I didn't screw it up tightly in the first place...

 

[Tomas Wangen]

I bought the Polar Pro Cinema filters. Screwed one on and had a devil of a job to get it off again. Had to make a tool to grip it (impossible with fingers alone). And no, I didn't screw it up tightly in the first place...

PolarPro are usually problem free to unscrew as long as you make sure you do not squeeze anything. If any pressure is applied it might seem completely stuck. Rotating without applying pressure should do the trick.

 

[Basspig]

Thanks, folks. I'll take a closer look at the links..

I always use a feather touch when screwing the filters on. Even the stock filter can be hard to remove at times.

What I'm most concerned about is optical quality.

I noticed the stock filter looses contrast when incident light from the horizon hits it. On ground based cameras, we use French flags and matte boxes to control off-axis light, but with the drone, other solutions need to be found. That's my biggest quality issue is the poor contrast in the upper half of frame.

The only single CP filter I could find was this one, with no reviews:

https://www.amazon.com/exec/obidos/ASIN/B071D8RDBV

While on Amazon, I saw a PENIVO CP filter with a high review rating. Going to check that out.

 

[msinger]

While on Amazon, I saw a PENIVO CP filter with a high review rating. Going to check that out.

FYI, the PENIVO CP filter is actually made by PGYTECH. It's just being resold under a different name ("PENIVO").

 

[Basspig]

I have a PYGTECH landing pad. Looks like they make a variety of stuff.. though I think optics are a specialized product line, requiring dedicated manufacture facilities. The reviews are good, but I wonder how many of these folks are viewing footage on a DCI 4K production monitor... a lot of gross flaws are invisible on normal computer monitors with the image scaled to 50% or less.

 

[msinger]

I think optics are a specialized product line, requiring dedicated manufacture facilities

Perhaps? If you research the companies selling drone filters, you'll find none of them specialize solely in making filters.

 

[Basspig]

That's somewhat worrisome. I know we had some time finding decent 4" glass polarizers for our 35mm cinema cameras. Some of the polarizers cost $400 and more! The cheaper ones degraded the resolution of the images and had strange flares when light hit them from incident angles.

 

[msinger]

Stick with the brands I mentioned above and you won't need to worry.

 

[ChrisLX200]

PolarPro are usually problem free to unscrew as long as you make sure you do not squeeze anything. If any pressure is applied it might seem completely stuck. Rotating without applying pressure should do the trick.

I spent a long time trying to coax the filter off and it was no-go. Stuck. I 3D printed a tool which gripped the filter all around its circumference and it still didn't work (just slipped). Finally, I stuck a section of rubber band around the inside of the tool and that released the filter - just. It was still a struggle. No, it wasn't cross-threaded either. Upon examination the threads on the camera seems to have some residue of coating which caused the sticking - so not a specific problem with PolarPro filters I suspect. Anyway, I ran a HB pencil over the threads to add a little lubrication and it seems to release easier.

 

[bkushner]

I bought the Polar Pro Cinema filters. Screwed one on and had a devil of a job to get it off again. Had to make a tool to grip it (impossible with fingers alone). And no, I didn't screw it up tightly in the first place...

That's why I like these filters. DJI Phantom 3 ND Filters and Accesories - Made in Chicago USA - DitzCo Great filters and easy to pop on and off..P3, P4, P4P

 

[Basspig]

I ordered an inexpensive CP filter and should have it next week.

I see that link offers linear polarizers, too. How well does the metering and autofocus on the P4P work with a LP filter?

 

[Basspig]

I got the polarizing filter last week and have used it twice so far. Frankly, I can't see a difference, unlike the 4" glass filters I use in a matte box with my 35mm cinema cameras. Those filters really turn the sky into the unearthly dark, saturated blue. But this filter has little effect. When I rotate it, I do see the sky darken a bit, but it's not dramatic like the large glass filter I own.
Need to do some more testing to see if it actually cuts down on haze. It DOES cut down on reflections off leaves. That much I can confirm.

 

[Deleted member 113105]

Anyone tried the DJI brand ND filters? Are they same quality as Polar Pro?

 

[Tomas Wangen]

I got the polarizing filter last week and have used it twice so far. Frankly, I can't see a difference, unlike the 4" glass filters I use in a matte box with my 35mm cinema cameras. Those filters really turn the sky into the unearthly dark, saturated blue. But this filter has little effect. When I rotate it, I do see the sky darken a bit, but it's not dramatic like the large glass filter I own.
Need to do some more testing to see if it actually cuts down on haze. It DOES cut down on reflections off leaves. That much I can confirm.

Due to the wide angle of the lens, you will only get a rather small band of full polarization gradually blending to effectively no polarization. It should help on reflections. To get deep saturation, certainly when including a clear sky, fixing in post is the best, easiest and most flexible option. If you do not see a gradual shift of tone across the sky, regardless of rotation, it indicates that the filter you have does not polarize much and more likely is closer to a nd filter.

 

[tman1972]

I use a CP, 4 and a 8 haven't needed a 16 yet nevermind a 32 or 64