Mountaineerfan's Blog

Well,here is is y'all.Pretty much anything you'd wanna know about chosing a set of binocs.I have to break this into four parts due to it being 16 pages long.Every other day I'll post a new segment.

Back when I was a kid I used to love filling my summer days by picking up my machette and heading out into the woods to make paths to places I'd never been before.Over this hill,beyond this stretch of wood,to the top of this mountain or that.I loved to explore.I had plenty of help too via my many cousins.Not suprising though as a great deal of people love exploring places they've never been and things they've never seen before.I know I still do.I reckon this is one of the main reasons I'm such an astronomy buff is because I'm constantly wondering what's out there.
Every time new images are returned from some distant world by one of our latest mega cool hi-tech wonderbots it seems just as thrilling now as it did when I was sitting in front of the tube back in 1976 seeing,for the first time,the first pictures ever returned from the Martian surface courtesy of the Viking Landers.That was awesome wasn't it?
Well, stuff like that is all fine and dandy but very few of us have access to the kind of jack it takes to build us a rocketship capable of hunting down other worlds.I might add though that I do indeed know a whole bunch of crazy guys and gals who are trying very hard to do just that while on a budget.Anyhow,despite our empty wallets we all still have a desire to explore for ourselves.Like many endevors we have a desire to do it for ourselves and to not be simply satisfied with someone else having all of the fun,after all this isn't New Jersey.So what to do?
Now is the part where optics come in.I,myself,have always been a champion of fine optics.Wether it be a set of binoculars or even a nice telescope fine optics help bridge the gap between there and here wherever either may be.Looking out into the distance and saying to oneself "I wonder what's over there" all one has to do is peek into the eyepiece and suddenly you've arrived.
Now if you're a regular reader here on the Fox Weather blog you may recall that I have stated my desire as of late to land a new pair of astronomy oriented binoculars.Let me state for the record that I am indeed still in the market for a good set of all around astro binos even though I just recently purchased a set of giant sized 100 mm binocs.Look for a review of them soon after this is posted.We won't discuss them much here because they are a whole different beast.
So,wether you're new to astronomy or even an old hand at it binoculars have a place in your optics arsenal for several reasons.First off is that they provide a good "grab-n-go" visual aid.In other words something that can be carried anywhere at a moments notice with little weight,size and hassle.The are very good for doing a quick survey of the night sky to evaluate your "seeing" ability in prep for whipping out the larger optics.You may not be able to get the kind of up close images that you will with a telescope you might still be suprised though at how much detail comes forth in places where you just saw none with the naked eye.
Binoculars also offer several other characteristics which are available in no other viewing aid.One of these is that they offer a right side up non-inverted picture.Telescopes do not do that as they are either upside down or mirror image reversed or both.Another pleasantry offered by binocs,and which happens to be my fave plus point,is that binocs give you a realistic 3D view of the sky.Sort of like ViewMaster view if you will.This is due to the fact that you are taking in two seperate images just as nature intended.Overall it's much more like being there in person than a single image telescope can duplicate.
Now you may remember my commenting to Skyguy a couple of months ago having my eyes on,figuratively speaking,a pair of Leupold 10X50's.Well,I decided to give it a bit of time and to keep looking.Nothing against them or anything but just not wanting to do things in haste.I even found a set of Celestron 8X56's which I liked a lot which may actually be better suited for astronomy.What would make them better?Well,y'all I'm afraid that explaining that is gonna mean having to sit through another one of my science lessons again.Since I've gotta think about all of this stuff I may as well drag y'all along with me so sit back and soak up a lesson in binocular speak as I share with you what I know about them and especially how it relates to my search for a good pair of astronomy binoculars.Sure I could just post some links to some on-line guides and all and say "good luck!" but for the reasons I spoke of above I've decided to engage in this labor of love.First we're gonna do though is cover some "quick" lessons regarding the terms and definitions used in the world of binoculars and optics.
Now before we do anything let me try to give you a truely nutshell explanation of how and why binocs work the way they do.As you'll soon see it's one of those true scenarios where a picture really is worth a thousand words.Not having any pics of my own to illustrate the point I don't wanna have to lift someone elses from the net.Yeah,I know you're all saying "since when the hell do YOU care about that?" Well never mind that just rest assured I'll post some links to some good illustrations you can use to follow along.
Alright,let's see how much we can cram into that nutshell.Follow along while I try to fit a bulldozer into an outhouse.Binoculars,for all practical purposes,are really just two mini-telescopes joined together with a hinge.Light enters through the front lenses,or objectives as they're also called,where it is flipped upside down much the same way as the lens(not the cornea)in your eye does.The inverted light beam then travels down the tube of the binocs where it then enters one of two differnt types of prisms.Prisms are angular shaped chunks of glass which serve a couple of useful purposes.First they take the inverted image from the binoc lenses and switch it back to upright.They also allow the use of large and/or widely spread main objectives while still allowing the eyepieces to stay fairly close together for comfortable viewing.The two types of binocular prisms you will run into are either Porro prisms or Roof prisms.
Just so I can get them out of the way sooner I will cover roof-prisms first.Roof prisms are what you usually find in small,compact binocs.They are aranged inside of the optical tube in an in-line fashion thus the usual straight tubed shape of most compacts.While their simple layout does make them a bit more rugged than Porro prism binocs they do have some faults.First they have what are known as "silvered" surfaces.Second,their design causes what's known as a "phase shift" due to the light beam being split and then realigned.Both of these drawbacks combine to reduce the amount of light transmitted through a set of roof prism binocs as compared to a set of Porro prism units with all other things being equal.A set of roof prisms can be seen here: http://upload.wikimedia.org/wikipedia/commons/7/73/A
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The second type we'll cover is also the type we'll be championing for our purposes and they are the Porro prism design.The Porro style prisms sacrifice only one thing and I'll get to that in a second.For the most part they fit our need because their layout allows the use of big main lenses while still keeping the eyepieces close together.Ever wonder why most binocs have that unusual "kink" in them?Well,it's because of the shape of the Porro prism design/layout which can be seen here: http://www.nightskyinfo.com/binoculars/binoculars_di
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The only real problem with Porro prisms is that they are a bit fussy about being perfectly aligned.As you can guess they are a bit easier to knock out of alignment.This alignment is called "collimation" and is important for proper,comfortable viewing.When collimation is out of whack,at a minimum you will probably notice a double,or split,image.Sometimes it may not even be noticable but will manifest itself in eye fatigue,dizziness or a slight headache.
Some binocs can be re-adjusted via screws on the casing of the binocs(usually under the rubber coating) or via eccentric rings in the main objective caps while some need to be sent to a technician.The eccentric ring style actually shifts the main objective and not the prisms.Frankly,I've never even seen a pair of binocs with this type adjustments.I'll try to provide a source for additional info on collimation adjustment by the consumer later.Just for note,collimation can also get thrown off when the two individual "telescopes" are out of alignment with each other.
Now the next thing you'll need to know about prisms concerns what they're made of.For the most part prisms are made of two types of glass,BK-7 borosilicate flint glass or BaK-4 barium crown glass.We can uncomplicate this subject real quick like by just cutting to the chase and saying that the Bak-4's are what you want.....period! No arguements,no debate,just Bak-4's.While Bk-7's may have been nice at one time they no longer hold a candle to the 4's.Yeah,some will say that "if this is just right" or "if you're viewing under such and such conditions,then..." but just ignore it and opt for the Bak-4's because they're light years ahead in every way.The most simple explanation as to why is that they just flat out transmitt an image better in both quantity and quality.Plus,Bk-7's have a tendancy to carry less light out near the edges of the image resulting in a picture that is sharp and bright in the center and dull near the outside.Fewer and fewer binocs are coming from the factory with the 7's these days anyhow.The binocs I just bought are a good example being as how the factory just started using the 4's in their construction less than a year ago.
Continuing to travel onward through our binocs the next thing we come to is the eyepieces and our way out if we're a beam of light.This is the spot where an image gets maginified.Other that that there's not really a lot to say as this device is usually fixed and forgotten so to speak.However,that is not always the case when it comes to the subject of focusing our image.I think now would be a good time to "focus" on focusing.
Generally there are three different types of focusing mechanisms on binocs.These include fixed focus,a central mounted focus mechanism and what's known as independant focus.Once again we will take out the trash first by coving fixed focus first.What these do is comprimise by setting the focus permenantly on a spot somewhere between their minimum viewing distance to infinity and hoping everything works out.Usually it doesn't.In a word they're junk and should be avoided.
The next type of focus is the most common and that is the central focus.Those are the ones with the lever or the wheel on top.This type has a mechanical device which moves the eyepices in and out.Their number one advantage is being able to focus them quickly for other viewing besides astronomy.They usually have another feature which is called a dioptic adjuster.This is basically a right side eyepiece which adjusts free of central focusing mechanism.The way it works is simple.First you close your right eye and proceed to focus your binocs while looking through only the left side.Once the left side is in focus you close your left eye and proceed to,while looking through the right side only,rotate the right side eyepiece until it too is in focus.Once that is done you then open both eyes and you should see a perfectly focused image.
The third type of focusing system used is one which is employed on a set of binos I've recently aquired and that is the independant focusing system.This system uses a seperately focusing eyepiece on each side of the binocs.One major advantage of this style is that it is quite durable due to having fewer moving parts than a central focus system.This system also allows for quite a bit of fine tuning of each eye seperately.As you can probably guess though it is a bit slow due to it only being practical on tripod mounted binocs.For the purposes of astronomical viewing a good tripod will figure in anyways so it's not a big deal.
This also seems like an appropriate place to cover what are known as zoom binoculars.In fact I can cover them with one word......junk! or at least for astronomy purposes.They are all junk no matter who they're made by.In fact since there are exceptions to every rule it seems like there would be one to this one.There is...sorta.The reason they are all junk is that while variable magnification zoom binocs may be a good idea the level of precision and quality of workmanship involved in the proper construction would be astronomical.Seriously astronomical.Most zoom binoculars tend to go out of collimation and have a blurred or double image at the higher magnifications.Another downside is their incredibly narrow field of view even in large aperature units.While I have seen many a good review of zoom binocs they are almost exclusively from terrestrial(ground) viewers and even at that I'm not sure many of those people know the difference.Also,in almost all of those reviews there is a "but this" or a "but that" and more likely than not it's the narrow FOV or the blurry images at high magnification.
Now as we move on let's take a second to talk about a component which,hopefully,our beam of light has passed through several times.This component is an often overlooked one by many.I am refering to the anti-reflective coatings on the optics.The main purpose of coatings is to cut down on reflected light which leads to dull and fuzzy images.For instance notice at night when you look at a window in your house and you see yourself in it?That is because the light hitting the window is being reflected back into the room.The whole purpose behind coatings is to stop that from happening thus giving the optics a chance to use all available light as well as being able to keep the light focused.It also prevents stray light from bouncing around inside the binocs and creating a "wash' effect where the image is fuzzied up by light scatter.To understand that last one just think about what happens when you hit the high beams while driving in the fog.
There are generally three types of chemicals used to coat optics with.On the low end of the pole sits magnesium fluoride,or MgF,which is actually a good material.However,a better coating system is called broadband multi-coating.This coating system is fairly new and uses different chemicals(sorry,I don't know what they are) to prevent the reflection of different wavelenths of light.This helps nab stray light at the far end of the visible spectrum,ultraviolet and infrared,where it gets harder to tame.The third type is to beware of and it's called "ruby" coating.First,it has nothing to do with "rubys".Second it is nothing but a trick that involves filtering out the color red so that bad optics appear to give a better image than they do.It's bogus! Do not listen either to any manufacturer's claims of "magical night vision" without batteries as some makers claim regarding "ruby" coated glasses.Besides all of that they leave everything looking green.Trust me when I say avoid them at all cost.In fact,now that it comes up,good quality coating should never impart any sort of un-natural tint to the image regardless of the color of the coating.After all the whole purpose of good quality coatings is to help transmit as much of the visible light(white light) spectrum as possible.
When your shopping for binocs you will see the quality of coatings expressed in one of four ways.These terms may sound more like a casual description rather than an official industry terminology but they are so don't take them lightly.The four seperate classifications,in order of lowest to highest quality,are Coated,Fully Coated,Multi-Coated and Fully Multi-Coated.
Going from good to best we'll start with "coated".Coated optics mean that only some of the optical surfaces are coated with MgF.Fully coated means that all glass to air surfaces are coated with a single layer of MgF.Multi-Coated means that at least some of the optic surfaces have multiple coatings.Finally,fully multi-coated means that all air to glass surfaces have been coated multiple times.Preferably these have been coated with multiple broadband coatings which you will see listed as fully broadband multi-coated.These are your best bet but may be expensive.
The next thing you should know about is "eye relief".Don't worry,this one is simple.In fact if you're not shopping for a rifle scope or do not wear eyeglasses then this one will probably mean little to you.Eye relief is basically the distance your eye must be from the eypiece in order to see properly.To a person with eyeglasses this becomes important because if the "relief" is too short then you will never be able to get your eye close enough to the eyepiece while wearing glasses.If you do wear glasses then you wanna make sure the binocs you're interested in have enough relief distance.I cannot tell you what is good in terms of "relief" concerning binocs as I don't wear glasses and have never had to deal with it.However,one place I do have experience with inadiquate eye relief is with several rifle scopes I have owned in the past as well as two Simmons 3-9X40 mm scopes I own now.Both of these scopes could use a good inch or better of extra eye relief in order to keep from having to climb so far up on the stock to get a good sight picture.In other words the eye relief could be longer.If you wear glasses then my advice is to go to a good optics/camera store and try out some binocs to get a feel for how much eye relief you'll need.Even if you're not gonna buy from them it's still a good idea.From what I understand if your glasses are for correcting near or far sightedness then you can probably do without them while wearing binocs.While I'm at it I might as well throw you a pic that illustrates eye relief too: http://www.nightskyinfo.com/binoculars-terms/eye_rel
ief.gif  One final note about eye relief is that while I have heard that there can be such a thing as too much eye relief I have never experienced it for myself and have in fact only ever heard one person complain about it.Being as how it refers to how far away the point where the eyepiece focuses the light is it could mean that those who experience it simply have smaller pupils.While it probably won't be a problem it's worth keeping in mind though.
This leads to our next fancy term which is Interpupillary Distance or,simply put,the distance between the very center of one of your pupils and the other.Binocs can adjust to fit most people but if you are a small woman or maybe a kid then a telescope may be a better choice for astro stuff although I'm sure that if you do plenty of looking you're bound to find a pair that you like and that fit you.The selection in today's market is just too huge to think otherwise.As for daytime binocs there are always compacts if you don't in fact find anything else.