Thursday, March 28, 2013

Need info on the Vortex 2x Doubler for binoculars


I was wondering if you had further info on the Vortex 2x Doubler for Vortex Binoculars, BAC-VT-2X; specifically:

Is it fully multicoated?
Does it have a Bak-4 prism?
Is it phase-coated?
Is it waterproof?
What are its dimensions?

Thanx, Tony


Hi Tony,

Thanks for your inquiry.  The Vortex 2x doubler is fully multicoated and waterproof.
It does not have any prisms in it, thus no phase correction needed.

The doubler weighs 3.5 oz, is 3" tall, and 1.75" in diameter at its widest point.

If you have any other questions, don't hesitate to email or call.


Eagle Optics

Tuesday, March 26, 2013

How can I find the weight of a product?

I'm looking at your website and do not see the weight of the products listed.
Am I missing something?


Elaine G.


Hi Elaine,

The weight of products will be listed under the "specifications" tab on all of our product pages.

I hope this is helpful.  If you have any other questions, please don't hesitate to email or call.

Eagle Optics

Wednesday, March 20, 2013

15x binoculars on a tripod

Eagle Optics,

I have a very good spotting scope, a fairly new Zeiss 85mm w/20-60x eyepiece, but I find hours of one-eyed viewing to be uncomfortable. I almost always use 20x, 90% of my scope birding is over water, and I find distortion and shake to negate any advantage from higher magnification.

I was considering mounting a 15x50 Vortex Viper on a tripod, but am reluctant to spend $650+ on an experiment that may be a failure and I have no experience with the stability or durability of bin/tripod adapters. I'm also a little reluctant given that I've seen only one or two folks in my 37 years of birding with a bin/tripod set-up.

Do you have any insight on this matter, pros or cons? Will you have any reps in Michigan, perhaps at a festival or show, where I might have an opportunity to try such a set-up? Thanks for any information you can provide.



Dear Matt,

Thanks for your interest in Eagle Optics. The tripod and binocular setup should work well for you and reduce eye fatigue since you’ll have both eyes open.

You’re right that most folks don’t use these setups. I’d argue that there are two reasons for that. Most of the time, people like the light gathering of a scope (bigger front lenses) and there is not a wide selection of binoculars in similar front lens sizes.

I guess a lot of folks also don’t mind the one-eye viewing. But if if is a problem for you, I think the bin/tripod setup might be your ideal fix.

We don’t have any upcoming festivals in Michigan, but we do have a full 30-day return policy. You have 30 days from the time you receive the order to set it up and check it out. If you’re not happy for any reason, you can return it in original condition for a full refund or exchange.


Eagle Optics

Monday, March 18, 2013

Is exit pupil related to eye relief?

I just need some clarification on eye relief and exit pupil.

It sounds like most binoculars today are made with ample eye relief so that most binoculars will work for people who wear glasses or don’t. However, in one description I read, it mentioned that having too much eye relief is a bad thing.

I did a quick little experiment with my Leopold rifle scope (which has an eye relief around 4”). When holding my eye about 4” from the scope everything is bright and I can see the full image in the scope. If I move my eye further away, the viewing area seems to shrink (vignetting as I have seen it described). When I move my eye closer than 4”, I cannot see the object very clearly either; the viewing area seems to move around and either get smaller or split.

Thanks for your help.



Thanks for your questions, Nick.

Too much eye relief is seldom a problem in a binocular. On a binocular, the function of the eyecup is to adjust for each individual user. Since you sometimes wear glasses, you'd be looking for a binocular with a minimum of 15mm. of eye relief. 

 Normally an eyeglass wearer would not need to twist the eyecups up--your glasses provide the distance needed for the correct focal point. Higher quality binoculars have multi-position eyecups to accommodate different peoples' needs.
Exit pupil is not related to eye relief.  Exit pupil, or, the dot of light you see coming though the binocular-- is the same size when your eye is at the eyepiece as it is when the binocular is held at arm's length.

Hope this helps. We can certainly chat at (800) 289-1132 if you have further questions.


Eagle Optics

Friday, March 15, 2013

Calculating a binocular's the field of view in degrees

Dear Eagle Optics,
What is the % angle of the Field of View of the Atlas Optics Sky King 8x42 Binocular?

Mitchell M.


Dear Mitchell,
Thanks for your interest in Eagle Optics. 

To get the field of view in degrees, you would divide the feet part of feet/1000 yards by 52.5.
So, the Sky King 8x42 binocular has a field of view of 6.9 degrees. (365/52.5)


Eagle Optics