Hi Guys:

I want to thank John Barsness (Mule Deer) for his latest excellent optics article, THE OPTICAL TRIAD: MAGNIFICATION, EYE RELIEF, AND FIELD OF VIEW, (click on the title), which you will find on the Campfire Home Page.

Please use this thread to ask John about the article. And I would be remiss in failing to state that his long awaited optics book MODERN HUNTING OPTICS is to be found at riflesandrecipes.com.

I will be getting my copy!

Thanks John, and thanks all.

Thanks JB, very nice read.

You are a valuable resource to this forum.


Again, thank you Rick for this place on the "Net"

Thanks!

That article is a good ready reckoner for the newbie and beaut revision for the experienced shooter.

Excellent, thank you.

Shod

Nice article and I'm glad to see there will be more on a monthly basis.

MD - when is the book shipping, or is it already going out?

Thanks

Nice! Thanks

Great article. I remember the old Leupold ads back in the 70's that had a diagram of the Optical Triangle or triad in them.

Thanks John!


Tim

Good read for sure.

Good article, John.

Swarovski has a long eye relief scope they call their EE (Extended Eye relief). Since it's in the lower magnification range (1-5), I expect it suffers less from the FOV loss; is that correct? I think something like that (120 mm or about 5 inches) would be ideal when mounting a scope with a relatively short mounting length on a long action rifle.

Yeah, especially when set on 1x!

With a scope set on 1x, or even 1.5x, you can generally just shoot with both eyes open, so essentially will have unlimited FOV.

Thanks.

What does zoom range mean?
I was looking at couple scope. Nikon monarch 2-10 power that has 4x zoom range and Minox ZA HD 2-10 power that has 5x zoom range.
If it's in your article and I missed, I apologize.
Thank you.

Zoom range simply means the ratio of minimum and maximum magnification. For many years after variable scopes became popular in the U.S. the most common range was 3X, as in 3-9x scopes.

But many companies eventually developed practical variables with even more magnification range, in part because shooters wanted the maximum amount of flexbility. The most I've heard about is 6X, with examples being 1-6x or 3-18x scopes.

Many companies use the zoom range in their model designations. Swarovski, for instance, has three lines of riflescopes, Z3 (with a 3X magnification range), Z5 (5X) and Z6 (6X).

Thank you, But I still don't understand how the magnification ratio works when you have a variable power scope.
What about fixed 6 power scope with 4x zoom range. is it magnified 6x or ?
sorry, I just want clear understanding

Fixed power scopes don't have a zoom range. Instead a fixed 6x scope only magnifies 6 times. In other words, when looking through the scope a target at 600 yards appears only 100 yards away.

A 3-9x variable scope can magnify the target 3x or 9x or anywhere in between, depending on where you turn the magnification ring.

That is a very informative article, especially for a neophyte such as me.

I have a question that is somewhat unrelated to the TRIAD. I have an early 1990s vintage Nikon 8x30 roof prism, green rubber-armored, individual focus binocular. With the individual focus, I can focus each eye separately once, and then the binocular stays in focus from short range to infinity. I always appreciated this feature because I can simply raise the binocular and instantly and clearly see what I am looking at without spinning a focus wheel.

What is it about this binocular that makes it able to stay in focus without adjusting for various ranges? I always figured it must have something to do with the individual focus feature, but I really don't know.

Also, why isn't this sort of binocular more popular, especially with hunters? It seems to be quicker and more fool-proof than spinning a focus wheel and maybe a diopter eyepiece. In fact, I can just glance at the settings by looking at the markings near the ocular lenses and know whether the bin has moved out of focus for my eyes. Typically, it doesn't, and so it is essentially always in focus.

What are the disadvantages to this type of binocular?

Thank you, and have a prosperous 2015!

In 8x or less magnification, individual focus binoculars are actually pretty practical for a lot of hunting. They work partly because lower-magnification binoculars have greater depth-of-field than 10x+ binoculars, and because our eyes can also focus a little to accommodate the view. IF binoculars are also very easy to seal against moisture, compared to focus-wheel binoculars.

IF, however, doesn't work as well with more magnification. Plus, bird-watchers buy an awful lot of binoculars, and they're typically glassing at closer distances than hunters, often less than 25 yards down to a few feet. They require quick-focusing, so most binoculars are made with the birding market in mind.

Thank you for that answer. It makes a lot of sense. When looking for Internet reviews of binoculars over the years, I discovered that there are a lot more bird-watchers than I would have suspected, and they certainly appear to spend a lot of money on glass. It seems that they buy glass like hunters/shooters buy firearms.

The funny thing is, I don't personally know any dedicated bird-watchers, and I don't believe I ever ran into one while in the outdoors. They must spend a lot of money on camo, too....

Actually, I haven't seen many bird-watchers in camo! They're kind of like wildlife photographers, mostly going to parks and other places where animals and birds are used to people, so are relatively tame.

They do spend a lot of money on binoculars, though, because like rifles for hunters, binoculars are their primary tool. About the only other thing they really need is a bird guide, and even the best one available for North America is less than $50.

Is there a way to determine actual magnification range for a variable scope? Leupold publishes the actual range in the Specs tabs, but I don't think other manufacturers do. I sometimes see actual numbers in reviews (maybe only for the Leupolds).

I have three Vortex scopes as well as a couple of Leupolds. Both are great scope companies, and I'm happy with the products. I don't think it really matters at my hunting ranges, but I'm curious about the Vortex actual numbers (Viper PST 2.5-10x44, Viper HS-T 4-16x44).

Thanks

This isn't a question about optics, but thought JB might want to know about this, which I copied and paste here from a Facebook friend's feed:

"There is some idiot on FB posing as John Barsness, the outdoor writer, contacting you out of the blue... I just blocked him. He indicates that Mark Zuckerberg has got money waiting for the needy... and surely at some point he will ask you for a token amount of money for you to get your hands on the big cheque. Don't fall for it."

RickBin : What happened to the newsletters ?

Very valuable resource.
I used to get e-mails with a link, but nothing lately.

These Links above don't work, and the home page doesn't show them either

regards,