Nature spotting scopes are useful for terrestrial or marine viewing, but can they double for astronomy use? In this article I discuss the pros and cons of using a nature spotting scope as an instrument for looking at objects, high in the sky.
What is a spotting scope?
A spotting scope is a type of refractor, designed for daytime observations of nature at a distance. The basic type is a straight-through design, with the eyepiece at one end, and the objective lens at the other. Others, like the one shown below, are angled scopes, with the eyepiece end raised 45º.
I’ve referred to these here as “nature spotting scopes” as they are primarily designed for getting close ups of animals and birds in nature.
Overview of a spotting scope
What is a spotting scope used for?
A spotting scope is used for land or marine viewing. Apart from use in hunting, the spotting scope can be a great tool for nature exploration and bird watching.
They are best used for looking downwards, at the same level, or up to shallow angles skywards.
These optical instruments can be somewhat impractical for astronomy as they are a tad awkward when you’re wanting to look upwards at objects in the night sky. More on that below.
Their range of magnification (can be up to 60x) is also limiting, though useful for looking at the Moon and the larger planets.
On the whole, spotting scopes do not make ideal astronomical telescopes.
This article will explore the idea, though, of using nature spotters for astronomy.
Advantages of using a spotting scope for astronomy
What can be good about them in hobby astronomy:
- A spotting scope is a light, compact device, which is a big advantage for those who want an instrument they can take with them when they’re on the go. They are portable to take on hikes or trips, similar to binoculars.
- Top rated ones are waterproof, preventing moisture from the likes of fog and mist entering the internals.
- They can be used without a tripod if you can stabilise them another way.
Disadvantages of using a spotting scope for astronomy
- Awkward to use when looking high in the sky
- Limited magnification
- Spotting scopes don’t usually have optical quality of an astronomical telescope
- They probably don’t offer the advantages in optics, coatings, or high quality glass of an astronomical telescope for the same price
- Images may have aberrations around the edges of objects
- You can’t modify them by swapping out eyepieces or adding filters etc.
How to use a spotting scope for astronomy
The first step is stabilising it. You could look to invest in a taller more robust tripod than the original or try some other form of steadying the scope while looking skywards. Apart from the tripod idea, you could get close to the ground and secure a steady hold by means of support not unlike using a set of binoculars for sky viewing. I explain ways in my guide to using astronomy binoculars.
- The angled spotting scope is said to work better than the straight-through configuration for sky viewing, but that could be a matter of preference.
The next step, is about having an aperture large enough for decent light-gathering. A spotting scope with an aperture of say 70mm, or at least a 65mm aperture, would fit best and allow some basic astronomical use.
Then, it’s about the quality of the images. With extra low dispersion glass (ED glass), you may get better and clearer views.
Summing up using spotting scopes for astronomy
You can use nature spotting scopes for astronomy, but they won’t give you the pleasure you’d get out of using an astronomical telescope.
On one hand, if your primary use for a scope is astronomy, it’s better to get a telescope rather than a spotting scope.
On the other hand, if you want a scope that lets you view animals and plants close up, but only on occasion, scan the night skies, then a good quality spotting scope is probably your best pick.
There are, of course, telescope types that can be used for both land and stars. This is one area where refractors, vs reflectors, can have an advantage.
- Dickinson, T. 2019. NightWatch: A Practical Guide to Viewing the Universe. Firefly Books.
- Hunting Optics on spotting scopes for astronomy