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Circular Polarized Lenses - God Rays no longer.

oOunknownuserOo
Expert Protege
So for sh*ts and giggles I decided to place a couple of my drones circular polarized lenses over the CV1 and night and day difference,  the god rays disappeared.

I tried a couple filters ND8/CP

and graduated ND16-8

The only thing with circular polarized lenses is that as you turn them you either have more light enter in, or you cut more out.    

These filters are godsend when shooting aerial photography with drones and you have sun flare,  

question is how could we mount them??
62 REPLIES 62

LZoltowski
Champion
@DaftnDirect   ... I do not have expectations .. I am incredibly patient, understanding of tech constraints (as I am a techy person who reads all sorts of science books) and I know what I am getting into with a first gen device .. have done it many many times ... 

You should have seen my face and hours of amusement with my first Furby ! lol

Enjoy the VR .. and I hope to see you and many others there soon! ... It can only get better from here right?
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Be kind to one another 🙂

Syrellaris
Rising Star
They are definitely worth it in photography. I use one on my Canon 650D and i love it 🙂

Btw i think it works because circular polarizing filters require longer exposure times for light. By not letting extra lighy trough and increasing contrast, it could i guess tackle the god rays?

I'll pick up a circ filter today and confirm my findings later... don't get excited though!

Percy1983
Superstar
Aren't cinema/polarised 3D tv glasses circular polarised?
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LZoltowski
Champion
From Quora .. IMAX uses linear ... RealD and others use circular:

Benefits of Linear Polarization
1) Linear polarization glasses are cheaper to produce and purchase than circular polarization glasses. I assume this is a big driving factor in the decision.

2) The process of linear polarization allows for lower light-loss than the process of circular polarization. Simply put, all things being equal with bulb brightness, screen, and throw distance, IMAX 3D is brighter than circular-polarization 3D systems. The brightness of image for a 3D film is a common complaint and almost all 3D system suffer from significant light loss compared to 2D projection. I think this is an important factor for IMAX, as they aim for premium audiovisual presentation. (Another drawback with Real-D is that they use a single projector for 3D, which results in compounding the light-loss problem.)

3) I haven't seen convincing hard facts to support this, but a lot of people say that a properly calibrated linear-polarization system will have less "cross talk" than a properly calibrated circular-polarization system. That means that if your head is straight with your eyes in a horizontal line, there will be less leaking of right-eye image into left-eye through the polarization. In other words, for normal usage the linear-polarized 3D should separate the left-eye and right-eye images better than circular-polarization would.

Benefits of Circular Polarization
1) If you tilt your head at all, linear-polarization cross-talk will drastically increase. You'll start to see combined images in each eye, ruining the 3D effect and potentially giving you a headache. The same problem occurs with circular-polarization, but at a much lesser degree. Supporters of linear-polarization believe that most people will immediately get that something is wrong when they tilt their head, and will adjust back to an optimal viewing position. However, this makes a big assumption about how viewers will react to a suboptimal image and also places restrictions on the viewer that might lead to physical discomfort while watching a long film.

2) This isn't necessarily a benefit of circular polarization, but the Real-D 3D system uses a single projector and the IMAX 3D system uses dual projectors. A big problem with using dual projectors is that if dust, hair, or dirt gets in a projector it will show up only in one eye's image, and that by using two projectors you are effectively doubling the likelihood of visible particles showing up. I can say that anecdotally I have noticed this every single time I've seen a film on IMAX 3D, but I've never had it bother me at a Real-D 3D presentation.
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FingerMcPokeye
Heroic Explorer
My guess on this...
xm30pqtp50jy.png

@FingerMcPokeye, nice diagram! that's my thinking exactly, so the Fesnel grooves, being circular, will produce radially polorized light, radial about centre of the Fresnel circle.

Now the thing is... the problem light rays are generated within the Fresnel lens... so... how is the light from these rays polorized? and are they're polorizes? and how would a filter, linear or circular differentiate between the incoming light and the internally generated light?

In any case, I still maintain that the only light that either filter would block is the uniformly polorised light because that's what both types of filter do... and I can't see that either type of light being emited is linear and there isn't a filter that blocks circular polorized light.

The circular polorizer emits circular light, it doesn't block it.

Anyway... I now have a circ filter so I'll try oit for myself (it would probably have been quicket to try it than type this!

@LZoltowski, I'm going to need a while to digest that!

LZoltowski
Champion
I have 30 pairs of realD glasses and about 15 pairs of Imax glasses lol I wonder if those would work as well
Core i7-7700k @ 4.9 Ghz | 32 GB DDR4 Corsair Vengeance @ 3000Mhz | 2x 1TB Samsung Evo | 2x 4GB WD Black
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Be kind to one another 🙂

checkmitch
Honored Guest
Would also be nice to have an amber tented lens option for less eye strain,  what has been everyone's experience using Gunnar eyeware and the like when using the Rift?  Is there a frame from Gunnars that has an ideal for VR use?

FingerMcPokeye
Heroic Explorer
Light that gets refracted passing through glass does not get polarized.

Light that gets reflected off of a surface gets polarized. 

Wear polarized sunglasses and look at a car window from a low angle.  Tilt your head back and forth for effect.  You'll see light coming from inside the window fine.  Reflections on the window will fade depending on head tilt.

With the freznel, anything hitting the glass at a near perpendicular angle will enter and get refracted.  Anything hitting near parallel will get reflected (and polarized).  The lens is designed so most light gets refracted, but the tiny slivers of vertical surface on the Fresnel will have light hit at near parallel angles.

Edit... adding..

So reflected polarized light is directional.  Non polarized refracted light has waves in all directions. 

If you put a polarizing lens between the Fresnel and the eye, the refracted light gets some small percentage of light blocked that happens to be randomly perpendicular to the lens polarization. 

But... the light that's reflected and polarized coming from the Fresnel will be fully blocked if the polarized lens is at a 90 rotation.