Binoculars: deciphering the terminology and how to use them

I wrote a similar tutorial last year. I guess it is buried under the deep water of inside passage. Since many people have come to this board to ask questions about binoculars, I figure it might be a good idea to update the previous post with more up-to-date information.

The frequently asked question on this board is whether to bring a pair of binoculars while doing a cruise vacation in Alaska. The short answer is: Yes. You should always bring a pair of good binoculars. I still remember past September when we sailed into Tracy’s Arm. Many people on board could not see the black bears on shore, other than some tiny moving dots (it sort of giving you a perspective how grand the Tracy’s Arm is). I was really glad that I brought a pair of binoculars to enjoy the wild animals on both sides of Tracy’s Arm: black bears, mountain goats, bald eagles. Our ship was also very close to Sawyer glaciers (about 1.5 miles). You can only see a vast wall of blue ice in front of you. But with our binoculars, we are able to see many details of the blue ice formation.

But, when it comes to binoculars selection, there is much confusion. I am trying to share my understanding with the fellow cruisers so to make your selection easier. It will break into 3 parts.

Part I: Terminology of Binoculars

Part II: How to Adjust and Use Binoculars

Part III: More in depth discussion of binoculars (to be added in a few days).

Part I: Terminology of Binoculars

A binocular consists of two optical systems that are joined by a hinge and (typically) share a common focusing mechanism. Binoculars are differentiated by their Prisms systems. Typically, there are two types of prisms: Roof prisms and Porro prisms. In Roof prism binoculars, the prisms are closely joined together, allowing the objective lenses to line up directly with the eyepiece. The result is a slim, streamlined shape in which the lenses and prisms are in a straight line. Roof prism binoculars are less bulky and more rugged than an equivalent Porro model. Most of the roof prism binoculars are capable of internal focusing, eliminating the external moving parts, hence easier to make them waterproof.

In Porro prism binoculars, the objective or front lens is offset from the eyepiece. Because of the simplicity of this system, some of the best values can be with a Porro design. As mentioned earlier, Porro system tends to be heavier and bulkier than their Roof prism counterparts. I have found it could be a real burden to carry a heavy Porro prism binoculars for extended period of time.

Now, let’s decipher the numbers of the binoculars: 10x42 for example. The first number is the magnification power of the binoculars. It indicates how much you can bring the object closer to you. The 2nd number is the diameter of the Objective lens in mm. The larger the objective lens, the more light that enters the binocular and the brighter the image. Some of us may have heard of Exit Pupil: It refers to the size of the circle of light visible at the eyepiece of a binocular. The larger the exit pupil, the brighter the image. To determine the size, divide the objective lens diameter by the power (an 8x32 model has an exit pupil of 4mm). To obtain a comfortable viewing experience, I would suggest a minimal exit pupil of 4mm. So don’t get excited if you find a pair of 16x32 binoculars for $30. Even though it has 16x magnification power, the objective lens diameter is only 32mm. So the exit pupil is only 2mm. It leads to a very dim and shaky image (remember 16x also magnify your hand shake as well). Do you know the exit pupil is not a mathematical term. We actually can see it. Hold your binoculars at eye level flat 1-2 feet from your eyes with eye piece facing you. Now, look through the eye piece toward a bright background. You will see a bright circle in the middle of the ocular lens. They are the exit pupil! You will see a 10x42 binoculars has a bigger cicles than 10x25 compact binoculars.

Alaska rains a lot, and the weather is very unpredictable, I would suggest you buy a pair of waterproof binoculars to protect your investment. They are O-ring sealed and nitrogen-purged for total waterproof and fogproof protection. These models can withstand complete immersion in water and stay dry inside. The interior optical surfaces won't fog due to rapid temperature change or humidity. A typical industry test standard is to submerge the binoculars into 4.5 ft water for 3 minutes and check its water hermeticity.

Then, there are a lot of talks about optical coating. Yeah, please buy the ones with optical coating, it reduces light loss by removing reflection at the surface of the lens and improves the viewing experience at low light situation. Here is what they typically mean for different coating techniques.

Types of Coatings:

Coated - A single layer on at least one lens surface.

Fully Coated - A single layer on all air-to-glass surfaces.

Multi-Coated - Multiple layers on at least one lens surface.

Fully Multi-Coated - Multiple layers on all air-to-glass surfaces.

Typically, an Emerald color coating has better light transmission than Ruby coating, which is, in turn, better than Sapphire coating.

How about prism glass, what is the buzz about the BAK4 optics? Most optical prisms are made from boroscillicate (BK-7) glass or barium crown (BAK-4) glass. BaK-4 is the higher quality glass yielding brighter images and high edge-to-edge sharpness. That’s why you always see the high end of binoculars use BAK4 only. In addition, when light travels through two piece of prisms, their optical path distance will be slightly different. As a result, the color might be off a bit. To compensate that, some high quality binoculars employ a technology called phase coating to correct the phase shift from the optical path difference. Those binoculars will have near perfect color rendering and you feel you are just viewing with your own eyes, except of much closer.

For people who wear glasses, you should also check the spec for eye relief. This is the measure between each eyepiece and your eyes while you view full images. With glasses, you’ll need 11mm or more of eye relief. I would recommend binoculars with adjustable eyecups. That means, the eyecups can be moved up and down to accomodate different viewing situation: If you wear glasses, you can move down the eyecups. If you don't wear glasses, you can move up the eyecups.

Part II. How to Adjust and Use Binoculars

From my experience of past Alaska cruising and many years of using binoculars for bird watching, I have found waterproof prism binoculars are the most versatile tools for my outdoor trips. They are lightweight, waterproof, rugged, and easy to handle. My DW has a pair of Nikon Monarch 10x42 and I have a pair of Zen-Ray SUMMIT 10x42. Both of them produce very bright, sharp images. Some people claim a $20 compact can do the same job as a full size binoculars does. I respectfullly disagree on that conclusion from my experience. Yes, a 10x25 compact can bring something 10x closer and does a decent job. However, as soon as people have tried full size binoculars, they will realize there is much a huge gap between decent and excellent job. For example, you won't see as much details, color might be off, image is much dimmer.

Since I have mainly used roof prism binoculars in the last 10 years, I will use them as an example to explain to how to adjust them. Other binoculars can be done in a similar manner.

1. First, you need to adjust the interpupillary distance of two halves of the binoculars to match with your eyes. You can do so by folding the binoculars up and down.
   
2. Then, you need adjust the eyecups: if you wear glasses, leave the eyecups down. If you don't wear glasses, twist the eyecups up. In the end, you want to push your eyes against the eyecups to get the broadest and brightest viewing.
   
3. Adjust diopter setting: when you view through binoculars through both eyes, sometimes, some people may found there is a eyesight difference between left and right eyes. Modern binoculars are equiped with a adjustment wheel called Diopter setting (typically on the right ocular lens). One can adjust that one to compensate the difference between two eyes. Here is how:

Overall, using a binoculars is very easy, probably much simpler than most of the point-n-shooting cameras. The myth about binoculars are hard to use is simply because many people's very first pairs are low quality, compact binoculars. Once you get a good pair, you will really enjoy the trip to Alaska and many, many other outdoor trips after that.

Before I forgot, there are two types of binoculars one shall NEVER touch with a 9 ft pole (don't flame me if someone has already done that. :))

1. Zoom binoculars. If a binocular claiming 20-80x 40 with maximal 80x power, run the other direction. At 20x, you can barely handle it. At 80x power, you won't see a thing. Trust me on that one.

2. Binoculars/Camera combo. A very good idea. But all the products I have seen are the combination of bad binoculars with worse camera. In addition, the camera uses different lens from binoculars, so what you see if not what you get.

Thanks for the tutorial, Dave! I still haven't played with the new binoculars that I got for Christmas. :eek:

Nancy, you are welcome. I guess it is time to take them out to try them out.. You don't want to be reading page 2 of instruction manual while the a black bear was laughing at you in a distance. :D Hey, I remember few years back when I bought my first external flashlight for my camera. My friend invited me to shadow him for a wedding photography. I was reading manual while taking pictures of the bride and groom. I think the newly weds were really freaked out about it. It turned out not too bad ( after all, I am just a free shadow photographer. :))

Dave, thanks a lot for such an excellent summary. I printed out a copy and saved in my scrapbook for reference. Our family had a great time using the zen-ray summit binoculars after following the other article of yours. Now DH just bought a Canon telephoto lens after he is convinced by you and several other members on those camera threads. He is really pleased.

You explained things very well, I really appreciate it! Especially how to set and mark the diopter setting. It worked great and we even made a different mark for each of us. This will save time and guess work, great idea! I took the advice on here a few months ago and ordered 2 pairs of Zen-Ray Summit 10x42. I'm so glad I did it; they are wonderful and sure to be used quite a bit next month!

Thanks again for your post! :)

Thanks a lot for putting together those information that were spreaded over many threads. I didn't realize the exit pupil actually means something. I do have one question: has anyone tried imaged stabilized (IS) binoculars? I have a IS lens for my camera and it works out great. Not sure if the IS binoculars make sense or not.

I do have one question: has anyone tried imaged stabilized (IS) binoculars? I have a IS lens for my camera and it works out great. Not sure if the IS binoculars make sense or not.

I tried some Canon IS binoculars in store before, even though I never owned one. The binoculars are bulky and heavy because of added weight from electronics and batteries. They are not the most ergonomic friendly design. The image quality seems ok, but one would expect more for those extra several hundreds dollars. The IS does a good job to stablize the image. However, for power of 10x or less, I found it hard to justify for the cost. I have heard few people complained about dizzy after using IS binoculars, but they are the minority out of the IS users.

I tried some Canon IS binoculars in store before, even though I never owned one. The binoculars are bulky and heavy because of added weight from electronics and batteries. They are not the most ergonomic friendly design. The image quality seems ok, but one would expect more for those extra several hundreds dollars. The IS does a good job to stablize the image. However, for power of 10x or less, I found it hard to justify for the cost. I have heard few people complained about dizzy after using IS binoculars, but they are the minority out of the IS users.

Thanks. I tried one in store today. I didn't feel dizziness afer using it. The image does seem to be stabilized. Yes, it seems to be quite heavy...

Great post, Dave. We have our Zen-Ray's and are ready to go! Any tips on cleaning the inevitable dust, fingerprints, and smudges off of the lenses?

Great post, Dave. We have our Zen-Ray's and are ready to go! Any tips on cleaning the inevitable dust, fingerprints, and smudges off of the lenses?

RC, excellent question! Take care of the lens of binoculars just like what you will do with your camer lens. I found most lens cloth coming with binoculars and camera lens is NOT adequate. Last year I bought a lens pen (its trademark is LENSPEN) from a camera store. It has a gentle brush on one end and a circular pad on the other end. I have to say, it is a magic product! Make sure you use the brush to knock off any visible dusts FIRST. Then use the circular pad on the other end to apply gentle circular motion on smudge or fingerprint. If there is some stubborn smudge, breathe over the lens, then apply the pad. The key is to remove any dust/particle first. Otherwise the pad will press against the particle over the lens and damage the coating.

I think those lens pens should cost around $10. A very good value

Thanks, Dave. I'll look for them.

Thanks, Dave. I'll look for them.

RC, please look for product like this. It may carry different brand. But they should be called Lenspen.

 

Part II. How to Adjust and Use Binoculars

 

1. Adjust diopter setting: when you view through binoculars through both eyes, sometimes, some people may found there is a eyesight difference between left and right eyes. Modern binoculars are equiped with a adjustment wheel called Diopter setting (typically on the right ocular lens). One can adjust that one to compensate the difference between two eyes. Here is how:

First, I put the lens cap on the right lens, while viewing through the left lens only. I normally use an object (using a book placed around 7-8 feet away seems works out great) and try to focus the left lens using the center focus dial. Once that is done, I will cover the left lens cap and open the right lens cap. Now, DO NOT touch the center focus dial any more. I will view through the right lens on the same object and focus to the sharpest point using diopter dial (the one next to right eyecups). This way, both lens are tuned in and the diopter setting is done. I then open both lens caps and use my binoculars.

You don't need to adjust the diopter setting any more unless it is changed

. I normally will use a sharpie to mark my diopter setting so I can just turn it quickly back to that position if it is changed, instead of going through the whole adjustment procedure.

Thanks Dave, that made sooo much more sense than the instructions that came with my binoculars! :)

One question - mine seem to have diopter setting adjustments on BOTH eyepieces, so it seems that I am able to adjust them separately. Can that be so? So I can just adjust each eyepiece by closing the other eye, and only using the wheel to focus further in or further out objects, yes?

Thanks!

Linda

Thanks Dave, that made sooo much more sense than the instructions that came with my binoculars! :)

 

One question - mine seem to have diopter setting adjustments on BOTH eyepieces, so it seems that I am able to adjust them separately. Can that be so? So I can just adjust each eyepiece by closing the other eye, and only using the wheel to focus further in or further out objects, yes?

 

Thanks!

 

Linda

Linda, two independent diopter setting is rare. The zen-ray summit and nikon monarch have diopter range +/-4, which should be plenty for most people. I don't know the range of your binoculars diopter. If it is +/-2 for each side, then it is equivalent to +/-4 for single diopter. Or if it is +/-4, then you got +/-8 single diopter equivalent, which 99.9% people won't have those level of different between two eyes.

To adjust them, use both eyes to focus on an object by dialing your center focus wheel to a comfortable level. Then, adjust each diopter by closing the cap on the other half. Don't touch focus wheel while doing that. Once you have made your adjustment, you will just need to dial the center focus wheel for the future use.

BTW, which brand do you have? I am curious since it is really hard to find one in any store now.. Thanks

Linda, two independent diopter setting is rare. The zen-ray summit and nikon monarch have diopter range +/-4, which should be plenty for most people. I don't know the range of your binoculars diopter. If it is +/-2 for each side, then it is equivalent to +/-4 for single diopter. Or if it is +/-4, then you got +/-8 single diopter equivalent, which 99.9% people won't have those level of different between two eyes.

 

To adjust them, use both eyes to focus on an object by dialing your center focus wheel to a comfortable level. Then, adjust each diopter by closing the cap on the other half. Don't touch focus wheel while doing that. Once you have made your adjustment, you will just need to dial the center focus wheel for the future use.

 

BTW, which brand do you have? I am curious since it is really hard to find one in any store now.. Thanks

Dave, thanks!

They are non-brand name my boyfriend got on Ebay for me. They have a hawk or eagle icon in a circle, followed by the word "Vision". They read "Night Vision 10x50WA". The print under that reads "360 ft. at 1000 yds. 120M/1000M field 6.8 degrees".

The diopters don't have any numbers other than the I in the middle, then a + on one side of it and a - on the other.

I did what you suggested and marked my settings with a marker, now my boyfriend can use them and I can get my settings back instantly.

I used to always get headaches trying to use binoculars. I think they didn't "fit" me. With your help customizing them, these don't seem to be giving me headaches. :)

Linda

Do you have any suggestions on how to steady the binoculars. Also, they may seem stupid but do you take your glasses off when using them.

Thanks, J

Dave, thanks!

 

They are non-brand name my boyfriend got on Ebay for me. They have a hawk or eagle icon in a circle, followed by the word "Vision". They read "Night Vision 10x50WA". The print under that reads "360 ft. at 1000 yds. 120M/1000M field 6.8 degrees".

 

The diopters don't have any numbers other than the I in the middle, then a + on one side of it and a - on the other.

 

I did what you suggested and marked my settings with a marker, now my boyfriend can use them and I can get my settings back instantly.

 

I used to always get headaches trying to use binoculars. I think they didn't "fit" me. With your help customizing them, these don't seem to be giving me headaches. :)

 

Linda

That's great! I am glad it worked out ok.. Have a lot of fun with it!

Do you have any suggestions on how to steady the binoculars. Also, they may seem stupid but do you take your glasses off when using them.

Thanks, J

There are two ways to stablized the view of binoculars: (1) don't go purely after the magnification power. 8x-10x is the best for stabilized view. 12x is marginal. Anything above that needs a tripod adapter. In my experience, 10x is best compromise for the power used in Alaska; (2) try to rest your elbows on some kind of support, like the railing on the ship. It will work out great. In addition, try to take many mini-breaks (like every 30 second) to rest your arms.

If you have a pair of binoculars with long eye relief ( the optimal viewing distance between the ocular lens and your eyes), you don't need to take glasses off. I don't wear glasses, but my DW does. She never takes off her glasses. The two pairs we have use adjustable eyecups: raising them up for people who don't wear glasses, or lowering them down for people who wear glasses. I recommend binoculars with least 11mm or more eye relief to accomodate the glasses. A good pair of binoculars allows you to push your eyes (or glasses) against their eyecups to see a very clear, bright view. On the other hand, people have to struggle with cheap binoculars to find a position to really see things through (which is why many people think binoculars are difficult to use).

Thanks, Dave, I have never really used binoculars before, and you have been really helpful.

Jane

If you have a pair of binoculars with long eye relief ( the optimal viewing distance between the ocular lens and your eyes), you don't need to take glasses off. I don't wear glasses, but my DW does. She never takes off her glasses. The two pairs we have use adjustable eyecups: raising them up for people who don't wear glasses, or lowering them down for people who wear glasses. I recommend binoculars with least 11mm or more eye relief to accomodate the glasses. A good pair of binoculars allows you to push your eyes (or glasses) against their eyecups to see a very clear, bright view. On the other hand, people have to struggle with cheap binoculars to find a position to really see things through (which is why many people think binoculars are difficult to use).

Dave, thanks for the advice. Both DH and I wear glasses, we can use our zen-ray summit binoculars without taking off glasses (following your suggestion to leave the eyecups down). They are just great! We will be going to fly to Seattle this Friday for our Alaska trip. Yeeee.. we are so excited.

Any suggestions on where to buy a pretty nice pair of fairly priced binoculars. What kind of binoculars does everyone seem to like, Help!

I would suggest that your time would be well spent at a store or stores that offer a wide selection of binoculars. You can see exactly what you are getting, learn a little and fit your budget. I have some wonderful Leica Trinovids that were an indulgence yet I still use and love an $80 pair of Pentax UCF’s.

These websites have reviews of most of the glasses available from branded suppliers. Take a look before you go shopping…

http://www.binoculars.org/birding/Reviews/Index.html

http://www.birds.cornell.edu/Publications/LivingBird/winter2005/Age_Binos.html

If you are determined to buy over the internet, http://binoculars.com/is a good starting place and they are competitively priced.

I wanted to get a second pair of binoculars for our cruise this past May so we would not be fighting over one. While using this web sight to research other "stuff" I had read some posts about the Zen Ray Summit binoculars so I splurged and bought a pair. My partner thought I was CRAZY for spending $150 on a pair of binoculars, then turned around and kept hogging my CRAZY binoculars because they were so much better than hers (Bushnell). I do not know a thing about binoculars, and I used to think the Bushnell's we had were great, but now they are marked for our next garage sale.

I wanted to get a second pair of binoculars for our cruise this past May so we would not be fighting over one. While using this web sight to research other "stuff" I had read some posts about the Zen Ray Summit binoculars so I splurged and bought a pair. My partner thought I was CRAZY for spending $150 on a pair of binoculars, then turned around and kept hogging my CRAZY binoculars because they were so much better than hers (Bushnell). I do not know a thing about binoculars, and I used to think the Bushnell's we had were great, but now they are marked for our next garage sale.

iluvnm65, I also have a 10 year-old bushnell that is quite heavy. I am thinking an upgrade for the next trip. How much better do you see? I have seen several other posters (LarryF, NancyIL..) mentioned the name and give some positive notes in their cruise review. Are you talking about the same thing? Do you have to buy from the store in your area? thanks