What Is A Spotting Scope?
A spotting scope is an optical instrument much like a telescope. They have a single lens and are designed to view objects in the far distance which makes them ideal for birding and other wildlife observation.
Spotting scopes have a higher magnification rate than binoculars making them great for observing birds found in inaccessible areas.
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Plus many birds are wary of people and will easily be scared off if you were to venture too close. A spotting scope makes it far easier to get a good view of these more elusive species without getting too close physically.
What Do The Numbers Mean On A Spotting Scope?
Binoculars have two numbers stamped on them separated by the letter X. On spotting scopes, there are typically three numbers with the last two separated by the letter X.
These numbers indicate the standard magnification level followed by the zoom magnification level, followed by the diameter of the objective lens. For instance a 20-60×60 spotting scope has a standard magnification of 20x which can be zoomed up to 60x and has a 60 mm diameter objective lens.
What Size Spotting Scope Do You Need?
The magnification power of a spotting scope is typically somewhere between 15x and 250x. You should go for an objective lens of at least 60 mm in diameter to allow for a clear, bright image.
Spotting scopes either have a number of fixed length eyepieces or a single zoom eyepiece. You should always start off using a lower powered magnification of around 20x when you start birding. Then increase the magnification once you have spotted the bird you want to study.
If your scope has various eyepieces they should have bayonet fitting to allow you to change the magnification quickly, as well as a simple mechanism for focussing. If your scope has a zoom lens, you can change the magnification from 20x to 60x using a simple adjustment.
Just like binoculars, spotting scopes will lose light and narrow the field of view as you increase the magnification. Which is why it's important to either buy a scope with interchangeable eyepieces or the highest zoom lens scope your budget will allow.
The Objective Lens Size
Just like binoculars, the diameter of the objective lens on a spotting scope dictates how bright the image viewed will be. A larger objective lens lets more light into the scope which makes the image brighter.
However, the larger the objective lens, the heavier the scope will be. This can be an important factor especially if you intend carrying the scope for long distances.
Close Focus
Close focus refers to the closest distance that an object can be viewed clearly. Due to the greater magnification power of spotting scopes, they're not really designed for close focus.
In fact many spotting scopes have a close focus of around 6 metres. Which is why you will always be better off taking both binoculars and a spotting scope out birding with you.
The Quality Of The Glass
The best types of spotting scopes are made from fluorite coated HD (high density) or ED (extra low dispersion) glass. These will offer far better viewing especially in low light conditions (like dawn or dusk) and when using high magnification.
Lens Coatings
To improve on light transmission the lenses are coated to help reduce glare as well. There are various different levels of coatings available on scopes but you should look for FMC or fully multicoated lenses as these have multiple layers of coatings applied to every glass surface.
Prisms
Just like binoculars, there are two types of prisms used to make spotting scopes which are
1.Porro Prisms
2.Roof Prisms
There are several differences between these two types of prisms but in general terms; Porro prisms are larger, heavier, more bulky, harder to waterproof and more prone to damage.
Which means you should go for a spotting scope with roof prisms if possible as these are more compact, less heavy, easier to waterproof and less likely to become damaged. However, they often cost more than Porro prism scopes.
Focussing The Scope
Obviously with greater magnification comes more possibility of an out of focus image. Many spotting scopes have a focussing ring at the front of the scope.
This can be difficult to reach forward to adjust every time you want to refocus on a moving target. I recommend getting a scope that has a focus knob positioned close to the eyepiece.
This allows you fast access to the knob without moving too much making refocusing faster and less of a hassle.
Eye Relief
There is a spot that if your eye is positioned the correct distance from the lens you can see the full image without any dark rings or loss of image. That spot is known as the eye relief and generally it's not that important unless you are an eyeglass wearer.
If you do wear eyeglasses you will need to take into account the eye relief of the scope as you will need to accommodate the size of the glasses and your eyes in relation to the eyepiece.
Eye Cup
The eye cup on a spotting scope will either be made from soft plastic or rubber and is designed to keep your eye in the correct position comfortably.
They are typically adjustable by either folding or twisting up and down.
The Viewing Angle Of The Scope
The viewing angle of the scope is an important feature which needs careful consideration when choosing a scope. Most serious birdwatchers prefer a scope with a 45o angle.
This is because this is the most comfortable whether you're standing or sitting down. Plus the 45o angle means the centre column of the tripod doesn't need to be raised quite as high which ensures a more stable image.
However, if you're planning on bird watching from a hide or a bird watching hut, a scope with a straight view might suit you better. You need to take time to consider this carefully because choosing wisely can greatly enhance your comfort and pleasure as well as the stability of your viewing sessions.
Waterproof & Fog Proof
This is an important factor because you're going to be out in the Great British weather which often provides all four seasons in one day. Look for a scope that has all of the air removed from the barrel and has been replaced with an inert gas like nitrogen or argon.
These inert gases prevent fogging or misting which can happen when changing environments or temperatures too quickly. Like getting out of a warm car into the cold frosty morning air for example.
Spotting Scope Tripod
When considering the scope that best suits your needs, it's a good idea to consider a tripod as well. Spotting scopes weigh far more than the average pair of binoculars which means holding a scope can be quite uncomfortable long term.
Prolonged usage of a spotting scope will almost certainly result in muscle cramps and fatigue. Not to mention the greater stability offered by using a tripod to support your scope.
Plus, if you decide to get into digiscoping, you'll need the stability that a tripod can offer.
What Spotting Scope Is Best For Birding?
Now that we've covered all of the basics with spotting scopes, let's take a look at the best type of scope for birding. Obviously everyone is different and what might suit one person might not be best for someone else.
However, in general terms, a decent spotting scope for birding will have:
1.A zoom lens rather than interchangeable lenses (for speed)
2.An objective lens of at least 60 mm
3.ED or HD glass
4.Waterproof & fog proof
5.Focussing knob with easy access
You should also keep as far away from a cheap spotting scope as possible because you almost always get what you pay for which often leads to disappointment.