Cambidge 302 display polarization

[JC]

Hi folks,
This weekend I flew a task with a borrowed 302.We are planning to
upgrade the panel and it was a good oportunity to try it out. It was
the first time I used one and I liked it but the display blacks out
with my polarized sunglasses and the only way to read it was lifting
them or tilting my head..
Is there a fix for this? Someone told me that newer units don´t have
this problem.
I prefer flying with polarized sunglasses so this would make me vote
against buying one in spite of it being a very nice instrument.
Thanks!
Juan Carlos

[qflyer1]

On Feb 13, 7:32*am, JC > wrote:
> Hi folks,
> This weekend I flew a task with a borrowed 302.We are planning to
> upgrade the panel and it was a good oportunity to try it out. It was
> the first time I used one and I liked it but the display blacks out
> with my polarized sunglasses and the only way to read it was lifting
> them or tilting my head..
> Is there a fix for this? Someone told me that newer units don´t have
> this problem.
> I prefer flying with polarized sunglasses so this would make me vote
> against buying one in spite of it being a very nice instrument.
> Thanks!
> Juan Carlos

You have to send it in to get the non-polarized display.
Been there.

Tim
1FL

[Tony[_5_]]

On Feb 13, 6:32*am, JC > wrote:
> Hi folks,
> This weekend I flew a task with a borrowed 302.We are planning to
> upgrade the panel and it was a good oportunity to try it out. It was
> the first time I used one and I liked it but the display blacks out
> with my polarized sunglasses and the only way to read it was lifting
> them or tilting my head..
> Is there a fix for this? Someone told me that newer units don´t have
> this problem.
> I prefer flying with polarized sunglasses so this would make me vote
> against buying one in spite of it being a very nice instrument.
> Thanks!
> Juan Carlos

get non-polarized sunglasses?

[stephanevdv]

On Feb 13, 3:38*pm, Tony > wrote:

> get non-polarized sunglasses?

Probably the best option. Polarized sunglasses have other problems,
sometimes creating dark zones in Perspex canopies. As far as I know,
there is no standard for the polarization of LCD-screens. You have to
turn your head one way for one instrument, the other way for the
other...

Good quality non polarized sunglasses are better for our purpose.
Something like Serengeti, Skylet etc.

[Andy[_1_]]

On Feb 13, 7:29*am, Tim Taylor > wrote:
>
> Fix it for free? *I wish. Just paid over $200 USD for the pleasure of
> letting Cambridge fix their own mistake.
>
> Good vario, lousy customer support.- Hide quoted text -
>
> - Show quoted text -

The issue with 302 polarization must have surfaced more than 5 years
ago, probably more like 8 or 9 years ago but I don't have my records
available. How old is the unit you experienced the problem with?

Andy

[JC]

On Feb 13, 1:21*pm, Andy > wrote:
> On Feb 13, 7:29*am, Tim Taylor > wrote:
>
>
>
> > Fix it for free? *I wish. Just paid over $200 USD for the pleasure of
> > letting Cambridge fix their own mistake.
>
> > Good vario, lousy customer support.- Hide quoted text -
>
> > - Show quoted text -
>
> The issue with 302 polarization must have surfaced more than 5 years
> ago, probably more like 8 or 9 years ago but I don't have my records
> available. *How old is the unit you experienced the problem with?
>
> Andy


I don´t know how old the unit is but it was purchased used for a good
price at a WGC. I guess the owner uses non polarized glasses..
It´s good to know that if we buy a new one it shouldn´t have this
issue.
Thanks for all the replies!
Juan Carlos

[Darryl Ramm]

There absolutely is a standard. Its to not polarize aircraft instruments so they conflict with Polaroid sunglasses--which are all polarized in the same direction to cut down on reflection off water/road surfaces etc. Cambridge simply (years ago) had a batch of 302s where the glass was installed incorrectly.

There is maybe less of a practical standard for handheld devices becuase some devices are intended to use in portrait or landscape orientations. Manufacturers need to make a best guess as to which orientation is more important for users wearing polarized sunglasses. If the device is only designed to be oriented one way then the choice for them should be obvious.

Polaroid sunglasses can have significant benefits to glider pilots, including making haze dome/wisps more visible (darkening the background sky and maybe direct polarizing effects) and making gliders more visible against darker sky. This is further enhanced if the sunglasses are strong "blue blockers". Besides difficulty reading some PDA/PNA etc. screens polarized sunglasses may show stress patters in canopies. I've flown in quite a few Mecaplex canopied aircraft with Polarized sunglasses and have had no problem at all with this. The side windows on my Toyota Tundra show more patterning.

As a final note some cheaper polarized sunglasses may suffer from poor aliment of the polarizers, so you'll see different darkening in each eye as you rotate say an PDA/PNA screen or even look at different parts of the sky.

Darryl

[Darryl Ramm]

Stupid automatic spell checker, "Polaroid" snuck in in several places.. I meant polarized.

[Darryl Ramm]

If you had an old C302 with this problem and Cambridge was no longer offering to fix the polarized screen problem for free I at least hope that for the $200 they upgraded to the new memory chips in this C302 (a change that was supposed to prevent invalid downloads), replaced the internal batteries and included a full recalibration. They have to recalibrate anyhow since the seal is broken.

Darryl

[Tim Taylor]

On Feb 13, 3:05*pm, Darryl Ramm > wrote:
> If you had an old C302 with this problem and Cambridge was no longer offering to fix the polarized screen problem for free I at least hope that for the $200 they upgraded to the new memory chips in this C302 (a change that was supposed to prevent invalid downloads), replaced the internal batteries and included a full recalibration. They have to recalibrate anyhow since the seal is broken.
>
> Darryl

Did include a new internal battery but no calibration all for only
$260 (including the shipping costs). I wear both polarized and non-
polarized glasses. With blue eyes the polarized help reduce fatigue.

Tim

[Tony V]

On 2/13/2012 7:32 AM, JC wrote:
> Hi folks,
> This weekend I flew a task with a borrowed 302.We are planning to
> upgrade the panel and it was a good oportunity to try it out. It was
> the first time I used one and I liked it but the display blacks out
> with my polarized sunglasses and the only way to read it was lifting
> them or tilting my head..
> Is there a fix for this?


I went to my optometrist and said that I wanted non-polarized lenses.
She said "are you a pilot?". I have a 302 that's polarized one way, and
a Filser radio that's 90 degrees different. There's only one "fix for this.

Tony "6N"

[Tony V]

On 2/13/2012 7:32 AM, JC wrote:
> Hi folks,
> This weekend I flew a task with a borrowed 302.We are planning to
> upgrade the panel and it was a good oportunity to try it out. It was
> the first time I used one and I liked it but the display blacks out
> with my polarized sunglasses and the only way to read it was lifting
> them or tilting my head..
> Is there a fix for this?


I went to my optometrist and said that I wanted non-polarized lenses.
She said "are you a pilot?". I have a 302 that's polarized one way, and
a Filser radio that's 90 degrees different. There's only one "fix for this.

Tony "6N"

[Garret Willat]

Go to a Camera store. Get a polarized filter. The one I got was about
8in x 8 in plastic and had a cardboard frame it was used to be placed
in front of a light for stage lighting.

I had a circle cut out of it and placed it over the glass display and
taped in place. Sit in the glider and rotate the polarized plastic
until you can see the 302 screen again. Used to do this in a borrowed
DG800. It was slightly darker than ideal, but worked fine.

[Dave Nadler]

Sunglasses block light polarized direction A.
Instrument polarizer blocks light polarized A+90 degrees.
In series they block everything.

Why does adding a third polarizer in the middle
allow light through ?

Spoooooookkyyy ;-)

[Darryl Ramm]

That was my first thought as well...

My only guess would be if the polarized gel filter was actually a circular polarizer (unusual for a gel filter). Circular polarizers consist of a linear polarizer layer on a 1/4 wave retarder layer that then rotates/circularizes the polarization. The coating on the C302 and other instument glasss is actually such a circular polarizer, with the linear polarizer layer outermost--bouncing off the glass changes the circular orientation handeness, back through he retarder layer again turns that circular polarization to linear but at 90 degrees to the linear polarizer layer, blocking the reflection.

If a circular polarizer film was held with the 1/4 wave layer side facing the pilot and the linear polarized side to the C302 glass and rotated so it is aligned to the linear polarizer layer on the glass then the pilot sees circular polarized light that his polarized sunglasses won't show orientation sensitivity to, but the overall image will be darkened... how is that for a hand waving guess? An obvious test is this will only work with only one side of the polarizer film facing the pilot, turn the film over and it will not work (it will go from dark to light as you rotate the filter but it won't improve problems with viewing with polarized sunglasses).

Darryl

[Dave Nadler]

Guess again ;-)

[Darryl Ramm]

And I'm sticking that guess until Garret tells us the test of flipping the gel filter does not work....

Ah winter r.a.s., how are all those PW5's doing?

Darryl