Neutral density filters for better view? (1 Viewer)

Kevin Purcell said:

The UV really doesn't get though the glass optics in a bin (you are looking through quite a thickness of glass that doesn't transmit UV at all well).
....

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(ronh)...A typical good sunglass lens, Bushnell's popular "G-15", transmit only 15%. That sounds severe, much less than any binocular I hope, but the eye's response is nonlinear so this isn't enough blockage to allow the pupils dilate if it's really bright, only enough so you're comfortable. Not to mention your cornea and lens aren't being cooked by UV....

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Kevin,

Although I would agree that UV isn't a problem using binoculars, I think ronh was talking about the protective effects of sunglasses, and the nature of the eye's nonlinear sensitivity.

An important point that tends to be side-stepped, I'm afraid, is that excessive light in the visible spectrum is no less damaging with binoculars than without them. Some might disagree, but I believe the image enhancing benefits of advanced coating technology would not be compromised by the use of neutral density filters, either in the form of sunglasses or as filters designed into the optical train.

For reasons that you mentioned, the use of polarizing lenses presents a different set of problems, probably more difficult with roof designs. But I agree that properly engineered they might also enhance certain types of visual task performance.

Regards,
Ed

I think placing filters in FRONT of the objectives is generally not a good idea, especially if you have paid $$$ for topline optics, as it is much more likely to degrade the image. Most camera lens filters on the market are not made with enough precision nor designed for the relatively high magnifications of binoculars. The few filters Nikon, Fujinon, and Canon sell for their bins are made for behind the eyepieces.

RJM said:

I think placing filters in FRONT of the objectives is generally not a good idea, especially if you have paid $$$ for topline optics, as it is much more likely to degrade the image. Most camera lens filters on the market are not made with enough precision nor designed for the relatively high magnifications of binoculars. The few filters Nikon, Fujinon, and Canon sell for their bins are made for behind the eyepieces.

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You know, filters are being made in big sizes (up to at least 77 mm) for photographic purposes where the demands on image quality are highly set.
And Hoya, Nikon and B&W surely know how to make such filters that don't compromise the view.

But the smaller filters of the eyepiece side are handier and cheaper, reason enough IMO

elkcub,

we needn't argue about the possibly eye-damaging effects of visible light when we talk about binoculars - simply because the problem is present all the time you are outside, not only when you put the bins in front of your eyes.

Thus, sunglasses are the most sensible way to address this/these problems.

One of many good choices:
http://www.randolphusa.com/products-sunglass.htm

Kind regards

//L

NDhunter said:

Jan:

This is to help you out with some winged eyecups for your Nikon. If you search back under threads under "eye shields", there was a discussion on
these by Field Optics. They are stretchy rubber and do fit the EII. The standard size is the one you want.

Jerry

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Thanks! I'll give them a try.

looksharp65 said:

elkcub,

we needn't argue about the possibly eye-damaging effects of visible light when we talk about binoculars - simply because the problem is present all the time you are outside, not only when you put the bins in front of your eyes.

Thus, sunglasses are the most sensible way to address this/these problems.

One of many good choices:
http://www.randolphusa.com/products-sunglass.htm

Kind regards

//L

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Looksharp,

I certainly agree with you. Eye-damaging effects of excessive light can occur with or without binoculars. In addition, what isn't often discussed is that when the eye's pupil shuts down as small as possible under intense lighting conditions (in the limit about 1mm±), this is only to protect it. Visual resolution (i.e., acuity) actually decreases because of diffraction effects. Hence, attenuating the incoming light with sunglasses would allow the pupil to enlarge to a heathy 2-3mm, which is the optimal region for visual acuity. (The acuity curve has a flat optimization region, bounded on one side by diffraction effects and on the other by aberrations.)

Regards,
Ed
PS. Those sunglasses look interesting, particularly the prescription ones.

That is correct, so I concur with you on those points. And I also know that you're familiar with the photochemical light adaptation of the retina, and that it provides the lion's share of the total light adaptation. The iris/pupil mainly provides short-term, fast light adaptation.

I have only seen pupils around 1 mm a few times, and those conditions were a result from either glaucoma medication or some psychopharmacological drug, both causing miosis.

In any case, I believe that very small exit pupils are not equal to larger ones for elderly people, even if their pupils won't open up as much as younger ones.

I did some one-man public brainstorming about this in another thread, but these speculations are just speculations rather than definite conclusions.
However, I think that we should think outside the box more, and I know that you and I follow a similar track there.

http://www.birdforum.net/showthread.php?p=1952425#post1952425