2018 December 27
What is the best telescope for an adult beginner?
Continuing my theme from a previous article ‘What telescope should I give a child?’, in this article I will be looking at selecting a telescope for an adult who is relatively new to the hobby, but who knows they are seriously interested. They may have attended stargazing events and already seen what celestial objects look like through good telescopes, and they may have joined the BAA or another society. Whereas in the earlier article I looked at sub-£200 telescopes, here I will consider those in the £400 to £1000 bracket, and try to make some sense of the bewildering variety available. All the quoted prices are as of December 2018.
Beginners generally have not decided in which objects they are most interested, and they don’t know whether they will always stick to visual observation, or become interested in imaging, so, we need to allow for these possibilities. But we do need to point out how different designs of the telescope are more or less suitable for particular purposes. Refractors of long focal length are preferred when crisp, high-magnification views of the Moon and planets, are required. They are also easy to use. They are, however, quite expensive for their limited light-gathering power. Newtonian reflectors give a larger aperture for the money, and this is better for detecting faint objects like nebulae and galaxies. However, they are bulky and less portable, as well as requiring maintenance in terms of collimation and periodic re-aluminising. Catadioptric telescopes like Schmidt−Cassegrains and Maksutov−Cassegrains are compact and versatile instruments, but expensive for a good quality aperture (150mm upwards). Likewise, short-focus refractors (less than f7.5 at 80mm aperture upwards), to give good images, need expensive ‘apochromatic’ optics, so I will not discuss these further here.
As stressed in the earlier article, the mounting of a telescope is as important as the optics. It has to be stable enough to allow the use of high magnifications, and it has to allow the telescope to be be pointed accurately to any spot in the sky. Telescopes may be hand-driven, or motor-driven, or computerised (GoTo systems). If you choose a computerised drive, you will get a less powerful telescope for your money.
I generally recommend beginners avoid GoTo telescopes. They sound like the answer to their prayers – a telescope that will find anything in the sky for them – but there is so much that can go wrong, and so much background knowledge of astronomy that is really required to get the best from them. They may be getting simpler to use, but I have seen too many cases of beginners buying GoTo telescopes and never getting much out of them. I only recommended them for those who are generally good with complicated gadgets. I think it is best for the beginner to develop the skills needed to point a telescope manually, to find objects in the traditional manner, using a finderscope, and get practice stepping from brighter objects to fainter ones. These skills can all be developed with a fully manual telescope. The intermediate possibility is a telescope that is not computerised but electrically driven to follow the stars. This does make it a lot easier to observe planets at high magnifications and to show objects through the telescope to other people.
With better telescopes, the optical tube assembly (OTA) is often sold separately from the mount, and I strongly recommend the purchaser go down this flexible, easily-upgradeable route, rather than buy a single package, because it’s usually better to get a bigger mount than manufacturers and dealers recommend for a particular telescope. The budget should be in the region of 60/30% for OTA and the mount, but this ratio should become more like 50/50 for computerised mounts.
So what are my specific recommendations? Here are some suggestions based on personal experience. It might seem like I am deliberately promoting Sky-Watcher telescopes here, but it is hard to avoid the fact that they do make a very high proportion of the telescopes in the ‘decent quality but affordable’ bracket.
For someone mostly operating in the city, usually observing bright objects, it is difficult to beat the ‘semi-apochromatic’ Sky-Watcher Evostar-80ED DS-PRO and 100ED DS-PRO refractors. These are now about £460 and £800 respectively. The latter is the better option for planets, the former for wide-field views. If the option of imaging is to be left open in the future, they should be combined with an equatorial mount, and I don’t recommended anything lighter than the Sky-Watcher EQ5, which is £245 for the manual version, which can be upgraded with drive motors, or even a GoTo handset, later.
A completely different route to go down is represented by the Dobsonian Newtonian reflecting telescope. If you wish to view faint deep-sky objects, this is a good way to spend your money. They are completely manual and are not portable in an aeroplane. For under £450 you can get the huge 250mm f/5 Sky-Watcher Skyliner-250PX. Sky-Watcher also makes driven GoTo Dobsonians, but the drives lack the accuracy of driven equatorial mounts. They are good enough for visual use, but not long-exposure photography. The smallest is the 200mm Skyliner-200P FlexTube SynScan for £749.
You can also put Newtonian reflectors on equatorial mounts. A classic beginners’ telescope is the 150mm f/8 reflector. You can get the Sky-Watcher Explorer-150PL tube for £179 and put it on a better mounting than it’s normally sold with. Again, I recommend that you use the EQ-5, then you’re spending £425 in total before adding any motors. This is a much better-value package in terms of what it will show you than the 100ED refractor, but rather less portable. It is as good for planets as the 100ED, and better for deep-sky objects. This is my top recommendation for most beginners: as the late Sir Patrick Moore might have said, it’s a telescope with which you can go a very long way.
David Arditti, Director, Equipment & Techniques Section