How To Choose Binoculars For City Viewing (Best UK Guide)

If you live in a built up city, possibly high up on the top floor of a tower block, then you’ll already be aware of the spectacular views you can get from your windows. You’ll also be aware of how much better those views could be if they were enhanced by using a decent pair of binoculars. Or maybe you’re looking for a good pair of binoculars to take to the local city park or outdoor space.

If you live in a city, and you want a pair of binoculars you’ve found the right article. In this article we’ll tell you all you need to know to get the perfect pair of binoculars for your needs. Be sure to read to the bottom as we have advice on using your binoculars in a city without arousing any suspicion.

Which Binoculars Do I Need For City Use?

To answer this question fully, there are two questions you need to ask yourself;

1. Do you intend to use your binoculars indoors?
2. Are you planning to go out with the binoculars?

The answers to these questions will determine which size binoculars you buy, because if you intend to use them whilst indoors, and you have sufficient space, you should choose a pair with high magnification that can be used with a tripod.

If however, you intend to take your binoculars out and about in the city, you’ll do better with a smaller, more compact pair that will be easy to carry and possibly easy to conceal too. You see, some people get weird when they think they’re being watched. So a compact, discreet pair of binoculars could save you some stress and embarrassment.

What Size Binoculars Do I Need For City Use?

The sizes of binoculars are determined by the size of the objective lens and have three size tiers which are;

1. Compact – Any binoculars with an objective lens less than 30mm is considered to be compact.
2. Mid-Size – Binoculars with an objective lens size of between 30 to 40mm are considered mid-size.
3. Full-Size – This refers to binoculars with an objective lens diameter greater than 40mm.

Although these sizes represent the three main binocular sizes, they don’t actually reflect the overall size of the binoculars, just the size of the diameter of the objective lens.

How To Tell The Size Of Binoculars At A Glance

We’ve just told you the actual physical size of the binoculars tells you very little so how do you tell which size the binoculars are? The size will be stamped onto the body of the binoculars somewhere. And will look something like this; 7×50 or 8×42, or 10×50. Any numbers upto and including the X represents the level of magnification.

Which in turn tells us how large images will appear when looking through that particular pair of binoculars. For instance 8x indicates that everything seen through the lens of those binoculars will appear 8 times larger than with the naked eye.

The numbers beyond the X indicate the objective lens diameter in millimeters. So using the 8×42 as an example, those numbers mean when you look through the lenses you will see objects 8 times larger than they are with the naked eye and the objective lens has a 42mm diameter.

Why Is The Objective Lens Size Important?

We can learn a lot about a pair of binoculars just from this set of numbers with the X separating them. Not only the magnification and the size of the objective lens, we can now also tell that as that particular pair of binoculars has an objective lens diameter of 42mm, they are full-size binoculars.

But that’s not the main reason the objective lens size is important, the truth is, for us to see anything through binoculars, we depend on light to illuminate the image we can see. Now, that light can only enter the binoculars through the objective lens. So the larger the objective lens size, the brighter the image we can see through those binoculars will be.

Exit Pupil

The beam of light that enters the binoculars through the objective lens is called the exit pupil. This is a very important feature because the exit pupil of the binoculars should be as close to the size of our own pupil size as possible. The human pupil has a diameter of between 2 to 4mm in bright daylight and dilates to around 5 to 6mm as the light fades.

The exit pupil isn’t always quoted in the specifications on every pair of binoculars but it’s an easy sum to calculate. Just divide the objective lens number by the magnification value, the answer will be the exit pupil in millimeters. Using our 8×42 from earlier, they have an exit pupil of 5.25mm because 42÷8=5.25. This works for every pair of binoculars and incidentally this particular pair will be great for daytime and even into early evening use in the city.

The Field Of View

Along with the magnification and the objective lens size, the field of view (FoV) is usually stamped onto the body of the binoculars and will look something like FoV 140m@1,000m. This means that when looking straight ahead you can see a width of 140 metres from a distance of 1,000 metres. When it comes to the FoV on binoculars anywhere between 105m to 140m@1,000m is considered to be good.

For usage in a city and especially from a high rise flat, the larger the FoV the more you can see without having to move your head at all.

Eye Relief

This is that sweet spot where your eye is positioned perfectly from the eyepiece to see the whole of the image through the lens clearly and with no dark rings or obstructions. There’s no point spending good money on binoculars to get good views of the city if they’re shrouded in dark rings. Common binocular eye relief ranges from 11 to 16mm and for most people anywhere between this range will work well.

Long Eye Relief

If you need to wear glasses even when using binoculars, then you’ll probably need binoculars with long eye relief. These give that extra space to accommodate your glasses whilst still allowing you the full view through the binoculars with no dark rings or blurry edges. Long eye relief is commonly anywhere between 16 to 24mm.

IPD

Interpupillary Distance (IPD) refers to the distance between your pupils. Everybody’s IPD is unique and to make binoculars work for everyone, the manufacturers include a hinge to allow you to adjust the distance between the lenses to fit your personal IPD.

Which Type Of Binoculars Are Best For City Use?

There are two main types of binoculars to choose from and depending on how you intend to use them one type will suit your needs better. The two types of binoculars are;

Roof Prisms

These are shaped like a capital H and are;

•  Smaller
• More compact
• Lightweight
• Easy to conceal
• Have a strong design (which won’t damage easily)
• Fully waterproof and fog proof. 

That’s the good news along with the fact that they’re easy to conceal which makes them perfect for use whilst walking about in the city streets. As we said earlier some people get slightly paranoid if they feel they’re being watched and the fact that you can hide these smaller binoculars away can make your life easier.

 Roof prisms do have a few negatives though, which include; 

• They cost more to produce 
• That cost is passed on to the customer and reflected in the purchase price
• They have a narrower FoV due to the position of the objective lens 
• They create an image that is between 12 to 15% less bright than Porro prism binoculars

Porro Prisms

These are shaped like a capital M, with a rather bulky midsection which is caused by the offset double prisms that are characteristic of this type of binoculars. They are also;

• Large
• Bulky
• Heavy
• Easy to damage (misalignment of the prisms)
• Virtually impossible to fully waterproof

If the prisms become misaligned, you will notice eye strain and increased headaches. Porro prism binoculars also have;

• A high light transmission rate
• Wide FoV
• More depth perception (than roof prisms)
• Stereoscopic vision
• Cost considerably less to produce
• A cheaper purchase price (quality wise compared to roof prisms)

Porro prism binoculars being larger and less able to be waterproofed are the better choice for indoor use from a high rise flat etc.

Tripod

As human beings, we all suffer from similar physiological problems. One of which is the slight shake we all have when holding any object for any length of time. This shake often goes unnoticed until we try to look through high powered binoculars.

That slight shake when magnified by 12 or 15 times creates an image so blurred as to be unrecognisable. Which is why we recommend only using binoculars up to and including 10x for hand-held use. Any magnification above 10x should be supported by a tripod or similar device. If you live in a high rise flat and intend to use high powered binoculars we would recommend a sturdy tripod.

If you have guests round and your tripod isn’t sturdy enough and they catch one of the legs just slightly, the binoculars could come tumbling down causing untold damage. There are some very sturdy tripods or other stands available and we’d recommend purchasing one to protect your binocular investment.

Other Things Worth Considering

We’ve covered most of the basics now, but there are a few other points worth considering before you make your purchase.

Light Transmission

Light is the most important requirement of a pair of binoculars because there can be no image without light. Manufacturers employ a few tricks to improve light transmission including;

Optical Glass

The top quality optical glass that’s used in the better quality binoculars is BAK-4 glass. This Flourite rich glass combination has the least imperfections of any glass and transmits light far better. The glass with slightly more imperfections but still precision optical glass is known as BK-7 glass and is the most common glass used in binoculars.

Lenses

It’s not just the prisms that affect light transmission, it’s also the actual binocular lenses. Look for extra-low dispersion (ED) glass or high density (HD) glass as these create a clear, crisp image with no colour fringing or haloing.

Lens Coatings

The lenses are coated to greater improve on light transmission and there are 4 levels of lens coatings which are;

1. Coated – This means one layer of coating on at least one piece of glass
2. Fully-Coated – This means each piece of lens has at least one layer of coating
3. Multi-Coated – This indicates at least one lens has multiple layers of coating
4. Fully Multi-Coated – This means multiple layers of coatings on every piece of glass, inside and out.

We recommend fully multi-coated (also known as FMC) as this gives the greatest light transmission and also reduces glare too.

Waterproof & Fog Proof Binoculars

Not so important if you never intend to take your binoculars from your flat but if you are going to take them outside look for nitrogen purged binoculars. These have all of the oxygen purged from them and replaced with nitrogen gas which is then sealed into the lens tubes. As the gas cannot escape, so nothing can enter either, no water and no dust too. With the added bonus of nitrogen containing no moisture so the inside of the lenses will not fog up either.

Protective Outer Casing

All of the top manufacturers coat the casing of their binoculars with either a rubber or polycarbonate coating to prevent accidental damage due to bumps or scrapes.

Warranty

All top binocular manufacturers offer lifetime warranties on their binoculars against any faults. Which means as long as they are owned by the original purchaser, any genuine fault will be repaired or replaced for the duration of your ownership.

Price Of Binoculars For City Use

It’s worth remembering that with binoculars you definitely get what you pay for. Cheap optics are often not too good and a decent pair of binoculars will cost you at least anywhere between £130.00 to £350.00 depending on the brand, make and model.

How To Use Binoculars From Home Without Looking Suspicious

There are many points to be aware of before using binoculars in the city, your own personal safety is paramount as is staying within the law. Although it’s not illegal to own or use binoculars from your city home, it is illegal to stalk. The police and local authorities are often unimaginative to say the least, so we’ve put these tips together in the hope of saving you any problems.

1. Keep The Room In Darkness
   You’re far less likely to show out to people outside if you are not silhouetted in light.
2. Draw The Curtains
   With the light off and the curtains drawn with just enough gap for your binoculars, there is even less chance of you being detected.
3. Choose Your Space Wisely
   Unless you are actually a peeping tom, you’ll want to look out over the city without actually spying on your neighbours. Choose your window wisely.
4. Wear Dark Colours
   You’re more likely to blend into your surroundings and therefore be harder to spot if you are wearing dark clothing.
5. Use Netting
   If you are particularly worried about being detected while using your binoculars indoors, cover your head and binoculars with some dark netting thus making you and your binoculars harder to spot.
6. Be Sure To Buy FMC Binoculars
   Fully multi-coated lenses give off far less glare and are therefore harder to notice.
7. Use Dark Binoculars
   Choose binoculars that have a black or grey body and also go for matte painted binoculars as they will reflect less light.
8. Use A Tripod
   Standing in one position holding binoculars can be hard work over a long period so make it easier for yourself and use a tripod or other support stand.
9. Use Compact Binoculars Outdoors
   Compact binoculars are easy to conceal in a pocket etc if necessary. Remember some people can become slightly paranoid at the thought of being watched. These people can also become aggressive too, so be ready to react.
10. Be Aware Of Relevant Laws
    It is not illegal in the UK to use binoculars in a city, town or open place, but there are laws protecting people’s privacy in their own homes. Take care when using binoculars in built-up neighbourhoods.

Frequently Asked Questions