How To Choose Binoculars For Moon Viewing (Best UK Guide)
Whether you use your eyes, a telescope or a pair of binoculars, the easiest object to spot in the night sky is the moon. We only ever see the same side of the moon because of the relationship between the gravity of the earth, and the rotation of the moon. According to NASA  the moon rotates at the exact same speed as it orbits the earth; this means that the same side is always facing us. They even have a name for this phenomenon, it’s called being “tidally locked”.
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The moon has no light of its own, it reflects the light from the sun or at times, it reflects the sun’s light from the earth, this is called “Earth shine”. When the moon is at its brightest, it is fairly easy to see features on the surface of the moon with just the naked eye. But for a clearer, more detailed image a decent pair of binoculars will be a great help.
What were just grey tones, become craters and mountains through the lens of a pair of binoculars. Slightly darker features become clearly visible as meteor craters.
What Magnification Do You Need For Moon Viewing Binoculars?
To see a far clearer image of the moon’s surface you will need a magnification of at least 7x, 12 to 15x will give a clearer view but not without the use of a tripod. This is because we all shake when holding an object in front of us for any length of time. It’s not usually a problem or noticeable but when magnified 12 to 15 times it becomes obvious and the image becomes blurry.
What Objective Lens Diameter Is Best For Moon Viewing?
The diameter of the objective lens is of great importance when it comes to binoculars in general and moon viewing in particular. This is because it is the objective lens that allows light to gather in the binoculars which in turn determines how bright the image will appear. Although the moon is bright (especially when it is at its fullest phase) unless the objective lens diameter is sufficient any image will appear to be dull.
The problem with the diameter of the objective lens is that the larger it is, the heavier the binoculars will weigh overall. Added to which as the objective lens is the lens furthest away from your face (eyes) the weight becomes more pronounced. So there’s a trade off between how bright the image appears and how long you can hold the weight to your eyes.
Plus, if the magnification is too great your arms will already be shaking, add extra weight to the equation and it’s a recipe for disaster. We recommend an objective lens diameter of 50 millimeters to be a perfect starting size for moon viewing. For hand held binoculars we recommend a 10×50 pair of binoculars to be the perfect size for moon viewing.
How To Tell Binocular Sizes
As you may have gathered from the above, the binoculars will have a series of numbers to identify their size, separated by the letter X. As we just explained, 10×50 is the perfect size for moon viewing that means a magnification of 10 times (the X represents times) with an objective lens diameter of 50 mm. 10x means that the object viewed through the binocular lens will be 10 times larger than viewed through the naked eye.
Which Type Of Binoculars Are Best For Moon Viewing
There are two types of binoculars, and they both have different properties they are;
Porro Prism Binoculars
These are the classic cartoon type of binoculars, shaped like a capital M, due to the configuration of the offset prisms. They are heavier, larger. Bulkier, harder to waterproof, but less expensive than roof prism binoculars.
Roof Prism Binoculars
These look like a capital H and as the name implies, they have the prisms set into the roof of each lens tube. They are lighter, smaller, more compact, easier to waterproof but cost decidedly more than a comparable Porro prism.
Other Recommendations For Moon Viewing Binoculars
Don’t waste your time with zoom lens binoculars for moon viewing. You might be thinking zoom lens binoculars to be a good choice, but not only will the magnified image shake to the point of being unrecognisable, but zoom lens binoculars have problems with distortion without shaking.
Compared to telescopes, binoculars have short focal lengths which means the image is prone to
Chromatic aberration. This means not all of the colours are visible at the same time which leads to a poor image. ED or extra low dispersion glass used in making the lenses and prisms allows for less chromatic aberration which means a clearer, brighter image, with less colour distortion.
For ease of viewing binoculars are coated with special coatings, there are a number of different coatings available, but if possible choose fully multi-coated lenses. This means every lens is fully coated inside and out with multiple layers.
We live in the UK, that means at some point or other we will get rained on. It makes perfect sense to have waterproof binoculars to protect your moon viewing investment. There are many levels of waterproofing available, but IPX6 will prevent any water entering your binoculars and causing any damage. The coding is a bit confusing but IPX6 will prevent any rainwater from entering from any angle.
Binocular lenses can fog up under temperature fluctuations like moving from a warm room to the cold outdoors to see the full moon. They make binoculars fog proof by removing all of the air from the lens tubes and replacing it with an inert gas. As nitrogen or argon contain no moisture content, they will not react to temperature changes and can’t fog up. This doesn’t stop the outer lens from fogging, but this can be cleared using a soft lens cloth.
Once the gas is sealed inside the lens tubes nothing else can enter. This keeps the binoculars dust free, and keeps mould spores out too.
Having a tripod for your binoculars, makes them easier to use long term, because you will not need to keep hold of them continuously. It also allows you to have a higher magnification, but it does limit how quickly you can start moon viewing.
IS or image stabilised binoculars use the same technology that’s used in camcorders to detect any involuntary movements and compensate for them. The problem with IS binoculars is they are heavier due to the weight of the batteries stored on board to power the tech. Also the batteries will need to be recharged or replaced regularly.
Binoculars Vs Telescopes
The traditional way to look at the moon is through a telescope, but there are a few drawbacks with using a telescope. We have two eyes for a reason, it’s called stereoscopic viewing, it means we see in stereo. Using a telescope leaves one eye doing nothing, binoculars use both eyes. Telescopes are more prone to image shakes (without being supported by a tripod), even at low magnification.
Telescopes are almost always used with a tripod, this means it takes longer to set up than binoculars. Binoculars can be used for many more uses than just stargazing (or moon viewing). Precision telescopes will cost significantly more than binoculars. Binoculars are far more convenient to use than a telescope.
Some Of The Moon’s Pleasing Views
Looking at the full moon through binoculars will reveal many of the features on the surface of the moon. Seeing the rays that radiate from some of the larger craters like Copernius and Tycho for instance. The seas of the moon like Maria Tranquillitas or Maria Serenitatis which are different shades of grey, and feature many smaller craters within their confines.
Incidentally, the Maria Tranquillitas or sea of tranquility is where Neil Armstrong first set foot onto the lunar surface. Did you know that of the 1,940 named features on the moon, 1,545 are craters. These craters vary in size; one, on the right side just above the centre, Mare Crisium, is 354 miles across.
To the left side of the moon, is the dark patch that’s called Oceanus Procellarum, just to the left of that is the small basin Grimaldi, which is a mere 138 miles, Grimaldi is darker due to the lava that flowed many years ago. Other interesting craters include Archimedes, Mare Imbrium and Posidonius crater.
Frequently Asked Questions
Binoculars of between 7×35 and 10×50 are considered to be sufficient for moon viewing, but 10×50 will give you the best viewing potential.
10×50 are the perfect size binoculars for astronomy.