UK Optics - Beginners Guide to Binoculars and FAQs

Here is a beginner's guide to binoculars, giving an overview of some considerations when buying Binoculars.

We hope you find this information useful.

1. What do the numbers mean? Eg 8x42 on Binoculars?

The first number shown on your binoculars is the magnification factor. eg and 8x25 or an 8x42 magnifies 8 times, so the subject appears 8x bigger /8x nearer. Likewise a 10x42 magnifies 10x, etc.

2. Which Magnification is best?

This depends on the purpose and use of the binoculars. It is not always the best policy to buy the highest magnification binoculars.

Higher magnifications have some advantages and disadvantages:

Advantages:

a. Image will appear nearer and be magnified This is particularly suitable for looking at small birds and wildlife for detailed identification etc.

Disadvantages:

a. Larger magnifications will be more shaky and difficult to hold still as any hand movement will be magnified.

b. The image is less bright compared with a similar pair of less magnification. 3. They have a narrower field of view.

Generally 8x is ideal for general purpose including bird watching, and makes comfortable viewing for extended periods of time. 10x or 12x magnification can be useful if more power is essential, or for larger magnification. Larger and more powerful binoculars generally require use of a tripod for comfortable viewing, or you could consider a spotting scope, which have larger and variable (zoom) magnification. A tripod or mount (such as a car window mount) can aid pleasurable use and avoid a shaky image.

3. What is the Second number mean on the binoculars?

We have mentioned the first number is the magnification, and the second number is the diameter of the front objective lens (in mm) so an 8x 25 is 8x magnification and the front objective lens is 25mm and a 8x42 would be 8x magnification but a much larger diameter front lens of 42mm.

This would mean the 42s are larger (and heavier) pair of binoculars, and a 8x25would be small and compact pocket size pair.

4. What Size of Binoculars should I get?

This depends on the application. Generally if you want a very small and compact pair then you would be looking at 8x25 or 10x25s.

The things that will affect your choice are compromises in:

1. The Portability. There's no point in buying a huge pair of binoculars if you are not going to take them out due to them being too big or inconvenient.

2. Light / Brightness – a larger pair will be brighter, allowing more light to enter the lens, and be more useable in poor or dark light conditions. They will also generally show greater detail and clarity. A small pair of binoculars will be of little /limited use in poor light conditions.

More info on Brightness

Modern binoculars have generally improved over the binoculars you found in your fathers loft. Good quality binoculars are excellent in daylight and good in twilight. However at dusk / night the lack of light usefulness will be restricted.

One thing to bear in mind is that the brightness is relevant to the size of binoculars, the magnification, and how much light there is in the first place.

Factors affecting brightness are:

1. Bigger objective lenses will give a brighter (and somewhat clearer) image with all things being equal.

An 8x42 gives a brighter image than an 8x25. A bigger lens however means a bigger heavier binocular and other things being equal will be more expensive due to higher cost in materials.

2. More powerful binoculars appear LESS bright - e.g. a 12x50 will appear darker than a 8x50. More magnification loses a LOT of brightness.

3. Generally for a binocular which is HALF the magnification the image will be FOUR TIMES as bright.

4. Brightness is also affected by the quality of lenses, prisms and coatings, and this is generally reflected in the price.

5. What is Field of view?

The field of view (FOV) is how much width of the scene you can actually see and is measured as an angle in degrees. The field of view is affected by many design features the main one being the magnification factor. The higher magnification means less field of view.

For uses such as bird watching, a greater field of view can be important and useful, for example if you are observing flocks of birds.

As an example for a 8x magnification around 5 degrees Field of view is average, and up to 7 degrees excellent (very wide), but for 12x magnification 3-4 degrees is average and 5 degrees is excellent.

6. What is Eye Relief?

Eye relief is incorporated on the binoculars either in soft rubber eye cups or easy to often use screw eye cups which gives a little distance between the eyes and the binoculars making viewing easier and more comfortable, and to give the best (most) field of View. If the eye is too far away, then field of view will be reduced.

The adjustment can be altered to suit both spectacle and non spectacle wearers, and with spectacles less distance will be needed, (as there is already distance from the eyes to the spectacles.) What is dioptre setting, and why is it only on one eye? Generally most binoculars have a dioptre setting on one eye. Some have none, and some on both eyepieces.

If there is a difference between your left eye and your right eye, it can be adjusted through the dioptre adjustment. Looking through binoculars without dioptre adjustment will not yield a sharp, focused image if one eye sees things in focus while the other does not. It can also lead to eye strain.

Procedure to setting the Dioptre.

First (whilst closing your right eye) simply look through the left eyepiece with your left eye and turn the focusing ring to focus on a distant subject. Then look through the right eyepiece with your right eye while closing the left eye, rotating the dioptre adjustment ring to focus on the same object.

7. What are lens coatings?

Lens Coatings are specific treatment applied to the lenses for various purposes. There are a number of benefits of lens coatings on binoculars and optical equipment including to reduce glare, improve clarity and help to focus light at both ends of the light spectrum to obtain a sharper image.

If you remember your physics & science lessons you may recall that blue light does not refract /focus exactly the same as red light. That's the principle behind rainbows, which is light refracting through water droplets.

Without getting too technical, lens coatings are good, and generally in higher priced binoculars there will be multi coated lenses (more than 1 Coating) and also on more than one surface, or all lens surfaces (Fully Multi coated). There may also be coatings on the prisms inside the binoculars.

The price point will usually determine the overall quality of the binoculars, and the issue of lens coatings should not have a great impact on your decision of which pair of binoculars to buy.

8. How much shall I spend? / Which pair is right for me?

Although the saying goes the more you pay, the better quality you will get is true, this is only generally true if you compare binoculars (or any other product) from the same manufacturer and product range.

For example a £250 pair of 8x42 binoculars from, say, Opticron wll certainly outperform a £90 pair of 8x42 from Opticron. However for your application the £90 pair may be sufficient.

Also the £90 pair of 8x42s may outperform a £125 of 8x25 (pocket compact) of the same manufacturer, the 8x42 being bigger and allowing more light, and equal clarity as the compact pair.

However your choice of purchase may be the £125 compact pair, as it may offer you a convienient pocket compact pair of binoculars, rather than the larger 8x42s which you will not take out and use.

Other factors which may affect price (within a certain manufacturer) is that more expensive binoculars will use better materials and produce higher quality images may be more ruggedly constructed and/or have other features, such as Waterproofing / Nitrogen gas filled etc.

As a guideline of the same manufacturer and binocular size if you spend £150 on a pair of binoculars, you will get significant improvement over spending £75, However if you spend £300 there will be an improvement over the pair at £150, but the improvement may not be such a noticeable difference as between the £75 and £150 pair. Unless you have very good eyesight you may not even see the difference!

Ultimately you do not have to spend a fortune (unless you want or really need to) but having a reasonably budget will help to get the best pair of binoculars for your needs and requirements, and which will be pleasurable to use, and be better value over the longer term.

9. I've heard Leica / Swarovski are the best - is that true?

Well, whilst both Leica and Swarovski make excellent binoculars, they are expensive, and other makes (such as the higher end Bushnells or Opticrons) can equally match and surpass the quality of some other models for significantly less money.

You do to some degree pay for the name with certain manufacturers, and you do certainly pay for higher manufacturing costs of certain manufacturers of binoculars made in certain countries. Thus ultimately you do get much superior value for money from certain manufacturers such as Opticron, and have a very high quality optics and specifications for a very affordable price - and you wont be as worried to take them out and use them, which is worth consideration.

In the end, you must decide what is the best pair for your application, and budget.

10. Where shall I buy them from?

There are some great deals on the internet, and occasionally from Local stores. It is worth checking the prices between sellers, as one stockist may be offering the same product for much less.

However it may not always the best policy to just go to the absolute cheapest stockist - sometimes it is worth paying a little bit more to buy from a established and trusted dealer for your piece of mind.

11. Buying off eBay?

Buying new products off eBay may seem like a good idea at the time, but may not guarantee that you will have a fully valid warranty, or complete product, or valid invoice/ receipt, and from experience ebay is often more expensive than if bought a trusted internet official dealer.

Also often auction sites such as ebay do not have all the safeguards as internet or local businesses, as generally you are buying as a private sale, which is not regulated as a business is.

However eBay can have its place for second hand deals - but ensure you check the new price, and second hand values, as great deals on eBay seem increasingly difficult to find.

12. Buying New or Second Hand?

With binoculars, technology and manufacturing advances, the quality of the optics have certainly come on quite a way even in recent years, and generally a quality pair of new binoculars will certainly surpass an older pair of some years.

Also bear in mind that a second hand pair of binoculars (or any other product for that matter) requires the original proof of purchase for warranty purposes. Although there isn't too much to go wrong on a pair of binoculars, taking into mind a high quality pair will be waterproof, Nitrogen filled, and have excellent optics, and certain manufacturers / models come with a massive 30 year manufacturer's warranty, generally good advice is to buy new.

So if you opt to buy a new pair of high quality binoculars, you won't go far wrong, and should last a lifetime of pleasurable and regular use.