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Polarized optics in binoculars? (1 Viewer)

E

edwincjones

Well-known member
Another thread mentioned Byfield Optics and their polarized binoculars.

I have not heard of them-any feedback as to their usefullness?

edj
 
There are a couple of overviews :

Byfield Recon 10x42 - http://www.birdforum.net/reviews/showproduct.php/product/445/limit/recent

Byfield Tracker 8x56 - 8x56 http://www.birdforum.net/reviews/showproduct.php/product/453/limit/recent

Both of these were written by me.

As far as I am aware there is not a US distributor yet although anyone wishing to purchase can order directly from Byfield Optics.

Of the two specifications I prefer the 10x42 simply for its ease of handling, but both are useful, very useful, for specialist applications.

Thanks for your interest.
 
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Polarizing filters have been in use for a long time now in cameras,
so it should help to see what they do there:

http://www.cambridgeincolour.com/tutorials/polarizing-filters.htm

Some good demonstration pictures.
They reduce haze enough to more than make up the losses in increased saturation
and contrast. On glare (sun near the field of view) they are even more effective.

If you can lay your hands on a polarizing filter for an SLR you can try the effect out,
at least in a kludgy way (tape, holding over with hand, etc).
 
Why no ''transition'' type lens in binoculars? Only in effect when conditions warrant so you don't have to be compromised when viewing is optimal.
 
Is there a difference in view between these binoculars and the effect of wearing polarized sun glasses while using a non-polarized binocular? Just wondering. Anyone out in this forum who can speak to my question?

John
 
james holdsworth said:
Why no ''transition'' type lens in binoculars? Only in effect when conditions warrant so you don't have to be compromised when viewing is optimal.
Click to expand...

Transition lenses allow you to adjust the FL of your eyes, for effective
depth of field... at a definite cost in field of view. The job is less important
and much more complicated for binoculars, and the loss of field through the
long barrel would be pretty harrowing in terms of moving the things.
Fast focusing is the answer these days.
 
John Dracon said:
Is there a difference in view between these binoculars and the effect of wearing polarized sun glasses while using a non-polarized binocular? Just wondering. Anyone out in this forum who can speak to my question?

John
Click to expand...

I've tried it...the sunglasses dim things a lot, but the effect does happen.
But...that's 'linearly polarized'.

They are talking about circularly-polarized, though. That would be spoiled
a bit going through all your coatings and angles. So....you put the
filter in one place early on. front or behind only the objective.
Up front is best. Circular polarization means one axis at a wavelength
is 1/4 wavelength ahead/behind the other. That can go funky passing through
super-multi-coating.
 
John Dracon said:
Is there a difference in view between these binoculars and the effect of wearing polarized sun glasses while using a non-polarized binocular? Just wondering. Anyone out in this forum who can speak to my question?

John
Click to expand...

My question would be: "How much light throughput is being cancelled by the polarization?"

Bill
 
I use polarised filters on my 15x Canons in bright snowy conditions and they work wonders. The drop off of light in those conditions are minimal.

Chris.
 
edwincjones said:
Another thread mentioned Byfield Optics and their polarized binoculars.

I have not heard of them-any feedback as to their usefullness?

edj
Click to expand...

Several years back Pentax sold waterproof bins that came with a set of screw-in polarizers. I have read that they can be very useful in bright over water situations but they do dim the image considerably.
 
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The human eye would see a 75% reduction in bright levels as a small change, physiologically.
In bright snowy conditions you would be reducing the blinding effect 2 ways.
Of course, brightness with lower contrast is just worse contrast.
I remember in optics lab, being asked to rate how much the light was reduced by a filter..
I said 50%. The meter said 90% reduction.
 
In the Byfield polarised binoculars, placement within the binocular eyepiece of an additional custom cut polarised lens array reduces light transmission by about 15%.

How does it work ? I don't know.

Just for the record I have no commercial interest, and yes, I do know the owner.
 
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Wow..pretty sophisticated.
They are taking advantage of polarization that occurs at the surfaces anyway.
Form the see glare comments, it isn't completely clear whether it's linear or circular,
but at 15% loss, it would be worth cleaning up the 'shiny glaze' at the edges of birds, water,
wet things, etc. The glaze is very 'violet', which is permitted free reign in most
(non-UVC filtered) multicoated binocs.

Very clever. The main new feature is the 15% loss (not the old-style 75% loss)
 
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Is the collimation off...or are those two models?

Very James-Bondish....could make a blind man talk about seeing again.
 
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edwincjones said:
Another thread mentioned Byfield Optics and their polarized binoculars.

I have not heard of them-any feedback as to their usefullness?

edj
Click to expand...

I've often wondered why some manufacturer doesn't offer threads on their objectives, even if just as a gimmick? One could use standard camera filters or other filters for different effects, including UV for cutting haze, PL for more vivid colors, amber for higher contrast, etc. I am aware of the light losses, but much of my viewing is in bright beach or snowy conditions.

Yes, it would be a niche product, but probably enough of a gimmick to sell enough to pay for its implementation....
 
If you read the (pretty credible) testimonials at the Byfield site,
they provide a dramatic difference under conditions of extreme
glossy sun-glare, exactly like polarized sunglasses do.
The difference is you are losing 15% of the light, not 75% (camera polarizer)
or 90%+ (sunglasses).

So it's much more than a gimmick of you are a fisherman or in the Navy or Coast Guard.

What it does for haze or sky scatter is less well-defined, however.
That application requires rotatable filters, or circular polarization,
depending on the angle of the sun. My first assumption about circular polarization
is not confirmed. The strength of the glare suppression at sea makes me
assume linear polarization for now...it would be optimized for looking towards the
sun a bit.

If you look at birds with sun flash within your field, it would be extremely effective.
Haze? Not sure.
 
I quickly went through the Byfield literature that is linked above trying to find out what kind of prisms are in the 8x56 but didn't find anything about it.

From its shape it looks like they have AK prisms. Does anybody know?

Bob
 
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