The Main Reasons Why Monoculars Are Good for Stargazing

are monoculars good for stargazing?

Monoculars are one of the most portable optical devices from the series monoculars, scopes, binoculars and telescopes. The difference between a monocular and a telescope is that monoculars are made to be portable and for short-range observations. But the question would be if the monoculars are good for stargazing.

Are monocular any good for stargazing? You can use monoculars to stargaze as long as the objective lens diameter is wide enough to capture a sufficient amount of light and the magnification is not too big for hand-held astronomical observations. Another advantage of monoculars is their compact size, which is suitable for travel.

Using a monocular to stargaze is not a big difference from using a binocular rather than you can observe through binoculars with both of your eyes, but in general, monoculars have the same or similar magnification ratio and objective lens diameter compared to regular binoculars.

As an instance, let’s have a look at a 12×55 monocular, and although the magnification is 12x which is above the optimum performance to carry on observations handheld (still, you may be able to do it, if your hands are steady), a 55mm objective lens diameter is wide enough to do even some deep-sky observations.

Are monoculars good for stargazing? Using monoculars to watch the stars.

Reflecting on the paragraph above, 10×50 binoculars are on the sweet spot to carry on handheld astronomical observations, to watch the moon, the Pleiades, to spot Andromeda galaxy and much more. Monoculars within this or approximate range would be just good but beware of the optics.

In general, monoculars are cheap on price and their optics may be underperforming to binoculars but not always. As an instance, I have seen monoculars 10×50 for $25 or about. Those optics behind are not recommended at all to carry on any astronomical observations.

Although we have here an exit pupil of 5mm which is not too bad in terms of astronomical observations, a 50mm objective lens diameter is good enough for this purpose. Therefore, if you want to focus on buying a monocular within this range, make sure you look for something with good optics behind.

The exit pupils of monoculars used to stargaze

The exit pupil is the beam of light passing through the ocular lens and goes into your eyes pupils. To measure the exit pupils, divide the objective lens diameter to the magnification (e.g. 50mm / 10x = 5mm exit pupil.).

In general, the human eye has the pupils open about 2-3mm in daylight conditions and up to 7mm during the night. For the best low light performances, the exit pupils of your monoculars (as binoculars as well) should be greater than your eyes pupils.

As an instance, monoculars 10×25 are NOT recommended for stargazing because of two obvious reasons:

  • The objective lens diameter is 25mm will underperform. I strongly recommend for night sky observations optical devices with an objective lens diameter greater than 42mm.
  • And the exit pupil is 2.5mm. As mentioned above, during the night your pupil opens up to 7mm, which means a lot of light is lost in the process.

As given the above example, a 10×50 monoculars can perform well in stargazing, where the exit pupil is 5mm.

The objective lens diameter of monoculars used for stargazing

I had pointed above that I do not recommend any optical devices, from binoculars to monoculars and scopes with the objective lens diameter smaller than 42mm

The objective lens diameter is the diameter of the front glass which has a direct impact on how much light is captured during the night. More light = better astronomical observations.

Monocular magnifications for stargazing

When we talk about magnification, some people may think that greater the magnification = better the observations. That is a false statement.

In general, it is difficult to carry any kind of handheld observations when the magnification is above 10x. And for a monocular to set up on a tripod? not so much

Therefore, I would recommend a magnification range of 8x or 10x with an objective lens diameter of 42mm+

You can watch the moon without any issues at 10x and identified some craters, although this would never outperform the power of a telescope for lunar observations, it can offer a great experience for anyone who wants to get started into stargazing.

What I do not recommend is to have monoculars with zoom (e.g. 10-30×50) for several reasons:

  • You may not able to carry any astronomical observations above 10x handheld
  • Monoculars with an active zoom perform worse than with a fixed magnification
  • There are more optics inside, therefore, the image quality overall is lower
  • Lots of light is lost in the process of zooming
  • On higher magnifications (e.g. 30x on a 10-30×50), the exit pupil is about 1.66mm, which is way too low even for daylight observations.

Monoculars vs binoculars for stargazing

There is an answer you may already know – it is better to perform astronomical observations with binoculars because you can watch through both of your eyes and offer a greater experience.

You can find binoculars dedicated for stargazing more than monoculars on the market, but hey, this topic is about if monoculars are any good for stargazing? yes they are.

What monoculars I would recommend for stargazing?

Furthermore, I want to create a list and try to cover which monoculars I would recommend for stargazing.

What I recommend: 8×42, 10×42, 10×50, 10×55, 12×55

What I do not recommend: 30×25, 50×60, 10×25, 8-24×40, 8×25

The above shortlist I created by watching and reviewing a series of monoculars and may not be explicit but recommended in general. Those are standard products to be found on Amazon.

But let’s focus a bit on the products I would recommend in this situation, right?

Opticron BGA 8x42mm Monocular (Amazon)

This would be my first recommendation to focus on stargazing with monoculars, due to the optimum magnification and lens objective diameter, multi-coated elements, high-quality roof prisms and nitrogen filled/waterproof.

The downside of this is the price, which may be a bit expensive to some of you, but the general high-rating speaks to itself.

Related Questions about monoculars:

Are monoculars any good for birdwatching?

Monoculars are wonderful optical devices to carry birdwatching observations and I would strongly recommend them due to portability and the simplicity of use.

A good quality monocular for birdwatching can outperform sometimes the binoculars because of better stability you may have when watching through it.

I recommend focussing on some quality monoculars are there are way too many cheap produced on the market which can underperform and create a bad experience for the viewer.

I would recommend nothing with a zoom range, but with a magnification of 8x or 10x and a lens diameter of 42mm+. Multi-coated monoculars and filled-nitrogen gas are recommended for better contrast and image resolution overall.

Are monoculars any good for stadium sports?

In the case of stadium sports, I don’t see why not monoculars can perform well, as binoculars are doing this already.

What I would recommend in this case is to have a monocular with a zoom range over the fixed magnification as you may need depending on your seat on the stadium.

I did mention way above that the zoom monoculars are underperforming, but let’s be a bit honest, we are not trying to do astronomical observations or birdwatching where we need quality above everything else.

Therefore, I would recommend in this case something like 10-20×50 (Amazon Link)

What is the difference between monoculars and telescopes?

The difference is that monoculars are small low powered telescopes designed to be used handheld and perfect for general observations while telescopes are the “big daddy” of monoculars, in special used for astronomical observations

In general, monoculars and telescopes and any other optical devices share the same structure of optics, but on telescopes this is extended to having mirrors instead of a lens, in special found on refractors and some other models, whilst monoculars may have in general one single structure of optics.

Monoculars can be used in astronomy, observing the moon and some deep-sky bright objects as long as the optics behind allows this. Following the rules and structures I mentioned above, you can stargaze with monoculars but definitely not with all of them, or better said with the majority.

If you don’t have yet a monocular and you want to buy one which may be used for astronomical observations, I would recommend knowing and researching what you buy before you do it, as you don’t want to spend your money on something underperforming

But always you will have the choice of using binoculars for stargazing, as they are more common than monoculars.

I hope that this article answered your question and to see you around. Take care my friend.

Gabriel Mihalcea

Passionate about binoculars, photography and blogging with years experience behind, I love to split my time and observe the beauty of this world with different eyes.

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