Binoculars as the first instrument for practical astronomy

Interested folks often ask for recommendations for a telescope and the amount of money required for it. In my opinion, binoculars are a far better first instrument for beginners. They are much more suitable for making quick, spontaneous and uncomplicated overview observations and for gradually getting to know the sky. In fact, you should first do this with your own eyes and then invest in optical instruments.

The ancient Egyptians, Greeks and other astronomers of antiquity achieved far-reaching insights solely through their observations without optical aids. It was only Galileo Galilei who used a small telescope to observe the sky, although he was certainly motivated to do so by his previous observations without an instrument.

Key advantages of binoculars

Binoculars are light, compact and portable. Therefore they can be taken anywhere. Be it a weekend trip or a vacation.
They are ready to use quickly and the smaller models do not require a tripod or mount. The larger models can easily be used on an azimuthal mount and on a stable photo tripod which might be already present in a household.
Binoculars for astronomy should have very good optics. Nevertheless, the purchase price is usually small compared to that of a telescope. You should definitely stay away from telescopes that are not on sale but are still cheaper than binoculars.
In addition to astronomy, binoculars can be used excellently for observing nature, for example ornithology. Here too, their good portability is a big advantage.
Binoculars have a large field of view. This makes it quick and easy to find celestial objects. Finding celestial objects is sometimes a big challenge, especially for beginners with a telescope with higher magnification. Many people lose patience and the fun of amateur astronomy.
As already indicated, small to medium-sized binoculars do not need a mount. A telescope requires a tripod and a mount that is as stable as possible. The tripod and mount are often a weak point in inexpensive telescopes on sale. This noticeably reduces the joy of observation and children and young people in particular lose interest in this wonderful hobby.
Observing with both eyes is more like natural vision. You can look through the instrument more relaxed and by using both eyes, a seemingly larger, more detailed image is “calculated” in the brain. For this reason, there is now a trend towards large double telescopes and binocular approaches are enjoying great popularity. All the advantages of bionocular vision can be found in the article (German) “Warum hat der Mensch zwei Augen – 5 Vorteile des Binokularsehen” on “ScioDoo [1].

For me personally, points 5 and 6 are the biggest advantages of binoculars. The literature list includes, among other things, a guide for different types of binoculars [2]. The associated price can easily be researched on the Internet or the corresponding models can be searched for on the used market. In addition to the relevant portals such as eBay or eBay classifieds, there are special astronomy forums that also contain boards with offers. An example of this is the forum Astrotreff.de [3]. My tip to start with, is a good pair of 8x40 binoculars or larger. If it's financially possible, I would start with a 10x50 glass. It doesn't necessarily have to be a new device. Binoculars are available in large numbers on the used market for comparatively little money. You can find something decent there for two to three hundred euros. You have to make sure that the device is in mint or near perfect condition. For most offers, this is the case. At least I haven't had any bad experiences personally yet. With a few exceptions, meanwhile I almost exclusively buy my optical instruments used.

Two other types of devices should be mentioned. On the one hand, binoculars with a lens size of 70 mm and above, which start at a magnification of 10x but are also available as 16x70 and more. Due to their greater light-gathering capacity, fainter objects can be reached and the higher magnification allows the first detailed observations of the moon or the migration of Jupiter's moons. The moons of Jupiter as such are already visible as star-like dots in 10x50 binoculars. Binoculars offer a deeper insight into the world of stars than you think. 10x70 binoculars can still be used hands-free for a short time. Anything above this can only be reasonably done on a stable tripod and, ideally, a sufficiently “robust” azimuthal mount to adjust the objects. For some models, special nebula filters are already available as accessories for “deep sky” observations.

Accessories

For small to medium size binoculares up to 50-60 mm lens diameter, there are no further accessories required, unless you want to do solar observations. Then you need a suitable, safe filter for each lens. Starting from 70 mm lenses, a stable tripod and a tripod adapter, see picture below, are required. Larger models are often equipped with a solid azimutal mount on a heavy duty tripod. Compared to a telescope, the range of accesories for binoculars is small. In addition for larger models there are special filters available which increase contrast of faint nebulae when doing deep sky observations. Looking for faint, large deep sky objects is another strength of binoculars as typically their field of view is large, much larger than in a telescope, even using moderate or low magnifications. It's really wonderful to walk across the night sky on a clear night with a good pair of binoculars and look at various deep sky objects.

Spotting Scopes

Significantly higher magnifications can be achieved with spotting scopes. They are a kind of hybrid between binoculars and telescopes. Spotting scopes for astronomy should have a lens aperture of 40 mm or more. In general, they are available with apertures of up to 100 mm and correspondingly high magnifications of over 100x. This makes it possible to study Saturn's rings and details of the moon's surface. As far as quality and price are concerned, everything is available here. The range goes from simple spotting scopes for €200 to high-end models from Leica, Swarowski or Zeiss for over €3000. Including eyepices and a photo adapter this can easly amount to around €5000 or more.

There is a lot of information available online about this. In contrast to an astronomical telescope, a spotting scope provides an upright, sideways image like binoculars and is therefore also suitable for observing nature. High-quality spotting scopes are the preferred instrument of ornithologists. Just like binoculars, spotting scopes are easy to transport. However, you absolutely need a very stable tripod and an azimuthal mount. At high magnifications, observation can become a nerve-wracking experience. With the help of a photo adapter you can take beautiful photos of the moon or distant terrestrial objects. The spotting scope then functions as a long-focal telephoto lens.

Spotting scopes are an interesting alternative and, to a certain extent, an intermediate stage between binoculars and a telescope. You can see the images upright and sideways like in binoculars. However, you no longer observe with both eyes, but with one eye, like with a telescope. Be reminded that the advantages of binocular observation should not be underestimated [7].

There are spotting scopes on the market that certainly come close to the performance and versatility of astronomical telescopes. The Kowa Prominar TSN-99 [], for example, has a four inch aperture and a first quality CaF / calcium fluorite lens. Standard eyepieces can be used via an adapter, so that very high magnifications of at least 200x are possible. With the quality of this optic, this is possible without any problems. The accessories for moon or planetary photography also leave nothing to be desired. For me, this look comes closest to a “jack-of-all-trades”, especially since it can also be used for nature/bird watching or for property protection.

However, without the optional zoom eyepiece or other accessories it costs around 3500,- €.

Downsides - There is no "free lunch"

So far, I have only spoken about the advantages of binoculars. Of course they also come with some disadvantages.

A main shortcoming is their limitation to low or moderate magnifications. Being an advantage to locate objects in the field of view, magnifications available in binoculars are too low to study smaller lunar or planetary details. Eventually if binocular journeys through the night sky have sparked further interest in amateur astronomy, it is time to think about buying a telescope. There is a lot of information available on the web, how to choose (and use) a first telescope. At some point, I will also elaborate on this topic in detail in another blogpost and offer some advice regarding buying a telescope. Obviously there is not a single one, all around, "one fits all" solution. Depending on the personal interests of an observer, there is a selection of optics that offer the best possible observation results. I my view a good pair of binoculars combined with a high quality spotting scope already covers many areas of amateur astronomy. In fact it maybe enough for anyone casually looking at objects in the night sky. It is definitely worth investing in quality when it comes to optical devices. It is usually a one-time purchase and, in theory, you can pass on binoculars and spotting scopes to your descendants. The “best before” date is unlimited if the optical devices are handled properly.

The Frankfurter Allgemeine Zeitung (FAZ) has published a "Kaufkompass", i.e. a buyer's guide, for spotting scopes [9]. In total this covers 15 spotting scopes in the price range from 150 to over 3,000 Euros. Theoretically there is something for ebveryone in this list. In this comprehensive guide, the pros and cons of each instriment are explained. In my view there is no single best spotting scope. It all depends on what you have in mind!

Personally I use the Leica APO Televid 82 pictured above and his little brother Leica APO Televid 65 with a 25x-50x wide angle aspherical eyepiece. The eyepiece is not quite a bargain (799,- €) but with an adapter it also can be used at any astronomical telescope. Its optical quality is outstanding and the eyepiece is well worth the price. The latter has the advantage of being much lighter, so I can take it with me into the mountains. All systems allow for "digiscoping", digital photography through a spotting scope, with digital cameras and smartphones with special adapters. Those can be obtained from the manufacturer via photography or astronomy specialist shops. Of course you can also use your classical analogue camera if you hae one. In both cases the spotting scope has the function of a telephoto lens.

I have taken the picture of the "Blue Moon", the second full moon within a calendar month, on 31 July 2015 with a Leica APO Televid 62, photo adapter and a Canon EOS2000D. The focal length was f=1280 mm. Leica APO Televid 62 is the predecessor model of the Leica APO Televid 65 with a 3 mm smaller aperture. The straight-vision version of the spotting scope was used to photograph the Blue Moon.

The In general the time around full moon is not ideal to take pictures of the moon. No contrasts can be seen because of the frontal illumination of the moon by the sun. Only the craters stand out clearly. One can see "Copernicus" nicely in the centre of the lower half of the moon in the picture above. Lunar photography will be another topic of this blog sometime.

A final remark regarding the pictures in this post

The binoculars in the sample photos are all in my possession but are not intended to be a specific purchase recommendation. There are several retailers that produce high quality binoculars. The readings mentioned in [4] and [5] provide very good instructions for exploring the night sky with binoculars. If you want to go deeper, I recommend the “Big binoscout” [6], which contains a variety of selected binocular objects including location maps. The type of binoculars required is indicated in each case.