Equipment Guide

If you are considering taking your first steps into astronomy, I hope this guide will explain the various ways you can enjoy the night sky, giving an idea of what you would expect to see, the cost and complexity. Along the way I will introduce terminology or supplementary equipment needed.

On a few occasions I have been asked by friends to recommend equipment to enjoy the night sky. This is an almost impossible question to answer as it poses too many questions back; what do you want to look at, how much do you want to spend and how much time do you have to dedicate to the hobby …are just a few of them. What I thought would make more sense is to outline various set-ups from the most basic to the most complex, borrowing from my own experiences working up to having a home observatory.

I hope it is useful and informative - you can read top to bottom or skip ahead to the bits that interests you. Note in all cases these are my opinions and I can only comment on what I have personally used.

Set-up A - Your eyes!

You don’t need any equipment to start to enjoy the night sky, and doing so without equipment will help you learn the key bright stars and recognise the planets.

• What do I need?

  Your eyes and a simple star guide (book/ chart) to help you locate bright asterisms. A compass might also help initially. You probably have one on your phone.

• What could I observe?

  This depends on your location and how dark your skies are, though typically with just your eyes you see the brightest stars, naked eye planets and the Moon. Learning the sky from key asterisms (see below) is a useful skill as your interest develops and you need to track down objects or align scopes. From dark sky locations you can see the brightest deep sky objects like M31 the Andromeda Galaxy and open clusters like M44 The Beehive Cluster and M45 The Pleiades. You can also see shooting stars (this only requires luck!) and meteor showers – when they are approaching always check the Moon cycle as this will wash out the fainter meteors.

• How complicated is it to use?

  Easy! Once you know the key brightest stars, try and locate the invisible arc across the sky called the Ecliptic as this is where you’ll find the Sun, Moon and planets.

• Cost? Free!

Set-up B - Binoculars

Binoculars are described with two numbers for magnification and aperture. 10x50 means 10x magnification through 50mm diameter apertures. Anything from 10x50 upwards will give great views of the sky, although the larger they get, the heavier they get. Anything above 20x70 may need a tripod, but the benefit of comfortable two-eye viewing cannot be underestimated and there is plenty to enjoy. Staying in a small patch of sky you can ‘star-hop’ your way to fainter objects.

• What do I need?

  10x50s binoculars or larger (a tripod if over 20x70s) and a star guide book/ chart.

• What could I observe?

  Binoculars will afford great views of the Moon’s seas and craters and are a good introduction to double stars (either binary systems or stars that appear close due to line of sight). Decent binoculars held steady will also resolve Jupiter into a tiny disc with 4 moons – observing this over successive nights will reveal the motion of the moons. From dark locations, deep sky objects like galaxies and nebulae can be picked out as ‘faint fuzzies’ against the backdrop of space. Bright comets can also be seen as fuzzy green stars. It is often these glimpsed views that inspire people onto larger optical devices with greater light capturing power. Binoculars views, being correctly oriented, also are versatile for terrestrial use and nature watching making them a good investment.

• How complicated is it to use?

  Easy but accurate pointing could be a challenge at first. Picking out bright objects and hoping to others requires practice an appreciation of magnitude (brightness) of stars as you will instantly be confronted with many more stars than the naked eye can pick out. With a little practice you could learn to plot a path to comets or small objects using brighter stars as a road map.

• Cost? From c.£50 for 10x50s, up to £100 for 15x70s, £100-150 for 20x70s. Tripods £100+ plus adaptor c. £20. For high-end brands you should double or triple these prices.

Learning the sky - asterisms not constellations

Everyone has heard of constellations but few have heard of asterisms. This is probably due to astrology and ‘star signs’ being used in common parlance. Leaving mythology aside, the constellations help classify stars by giving them names and numbers. But the constellation boundaries cannot be seen, they vary greatly in size and they do not provide a helpful way the navigate the sky.

Novice astronomers find it hard to appreciate what constellations are. They say “what is that constellation?” and point to an area of sky where they see four bright stars, all actually in different constellations. They also expect to see a familiar shape and get disappointed when the constellation bares no resemblance to a swan or a fox or a dolphin; another reason to not get hung up on constellations. Think of them like election constituencies - they have importance for administration but would be very difficult to recognise on a map.

What you need to navigate the sky is to find familiar patterns of stars that help you orient yourself. These are called asterisms and ignore constellation boundaries and star classifications; they are simply patterns. Sometimes the patterns form the brightest part of a major constellation. Sometimes they combine the brightest stars from neighbouring constellations. The point is that they are unmistakable. 

We have all heard of the plough, or the big dipper, or the saucepan. This asterism of 7 bright stars is part of a wider constellation of Ursa Major; The Great Bear. Don’t look for a bear as you won’t find one, look for the saucepan. Ursa Major is a northern constellation, as it is only visible to observes in the northern hemisphere, and it is circumpolar, meaning it is visible all year round; it never sets. 

The seven bright stars that make up the saucepan cover a large area of sky and is normally easy to locate. Three stars form the ‘handle’ and four stars form the ‘pan’. It is a constant shape but may appear right way up or rotated, like the saucepan is standing on its handle or on the sides of its pan. The two stars that form the right hand side of the pan are known as ‘the pointers’. Draw a line between them from bottom to top, and then keep going until you hit the next bright star. This is Polaris - the North Star. From anywhere in the northern hemisphere, by turning to face Polaris you are now looking directly north, with east to your right, west to your left and south directly behind you. Finding north is crucial for aligning a telescope mount.

You will need to learn a handful of asterisms to have some sense of where you are looking through the seasons. Then learn the names of the stars in the asterisms. If you progress to a Goto computerised telescope, these brightest stars will be the ones it attempts to synchronise with. If you don’t know where the star is, you cannot align your telescope. Also, if you know the brightest stars and where they should be, if you spot a bright interloper you know you have found a planet.

Set-up C1 - Wide angle static camera

You could use this set up with no knowledge of the night sky and get great results, however it’s more fun to know what you’re looking at and plan for certain events like a conjunction of planets. All but the most basic cameras have the ability to take exposures of a few seconds or ‘bulb’ for as long as you require. For a wide angle lens on a static tripod, to avoid trailing an exposure of around 8-10secs is possible (you’ll need to experiment). If you want trailing then 30-60secs will be enough to carve out faint arcs. Stacking a number of images together will joint the arc up into long sweeping star trails.

• What do I need?

  A camera with the ability to take manual exposures, or as a min. 10-30sec exposures. The ideal camera is a DSLR with ‘bulb’ setting and a handheld intervalometer which means vibrations from pressing the shutter button are eliminated. Turn off automatic noise reduction and always shoot in RAW (the highest uncompressed data). You’ll want to pair the camera with a sturdy tripod with an adjustable ball head or handle-type directional head. Finally a decent lens; prime lenses (e.g fixed focal length) tend to be higher quality than zoom type. Wide angle, say 14-24mm-ish range will give an expansive view of the sky. The speed (f number) of the lens also helps, the lower the better. You will need to play with ISO sensitivity settings - something around 800-1600 will probably suffice. I am still very much learning this myself…

• What could I observe?

  Short exposures will reveal a multitude of stars and help pick out the key stars of a constellation or asterism. Longer exposures +20sec will reveal the motion of the stars (well, the Earth obvs!) and show faint detail like the Milky Way with a little software ‘stretching’. This is the perfect set-up for star trails; frame your composition, programme your intervalometer (30sec length, 10sec gap x ‘X’ number of shots) and leave alone. Photoshop or similar will enable you to layer up each frame to reveal a long star trail composition. Foreground objects add scale and interest.

• How complicated is it to use?

  Achieving focus on distant objects can be tricky, so focusing during the day is an options then turning off any autofocus. My 14mm Samyang lens has no autofocus, so I use a low-tech sticky label and pen mark to record the focus point. The Moon is a good infinity focus point. Otherwise the wide angle nature makes it pretty forgiving - point and shoot! 

• Cost?

  DSLR body say £400 new or £200 used. Lenses must obviously suit the body, branded lenses being expensive than non-branded. The Samyang lenses for Canon fit are very popular for widefield shots and start around £200-300 and can be found all over eBay. Intervalolmeter from £15-20 ebay. Lightweight tripods from £50 upwards (check the max. load of the camera and lens). Other extras: if you are shooting from an urban area then a light pollution filter could be useful Astronimik (or similar) have clips that sit into the camera body and cut out nuisance light pollution, from c.£120 to suit your camera type.

Set-up C2 - 200mm-400mm static camera

Longer focal length will give greater ‘zoom’ but from a static set-up only short exposures will be possible. This approach is less successful and less forgiving than wide field and ideally should be tracked, see C3.

• What do I need?

  Everything the same as C1, but with a telephoto or long prime lens. Crucially without tracking your exposures must be shorter to avoid trailing, perhaps only a few seconds. Increasing the ISO will help increase the sensitivity for shorter exposures.

• What could I observe?

  Brighter gas clouds like the Orion Nebula or the North American Nebula will be picked out faintly, especially with high ISO but are unlikely to make nice final images. Your best bet is the Moon, where the long focal length will start to resolve some detail. The Moon is also moving so from a static position after a few shots you’ll need to readjust your frame.

• How complicated is it to use?

  The downside with this setup is finding a specific object is very tricky and requires some precise pointing. You could use a laser pointer affixed to the camera to help but use sparingly - don’t let your laser spoil the skies for others.

• Cost?

  As C1 above except the cost of the lens. You can pick up high end lenses 300-500mm focal length second hand for £500-600, so equivalent to a small refractor of similar focal length.

Set-up C3 - DSLR on a simple tracking mount

A tracking mount will make a huge difference to your options, giving the ability to have long exposures trained on a patch of sky to soak up the photons. Single exposures can reveal faint structures and the dust lanes of the Milky Way. Tracking and stacking of images will increase detail further whilst controlling noise (the messy pixellation) from the camera sensor, which is only exaggerated when the sensor it working hard and getting hot.

• What do I need?

  One of the biggest developments in recent years has been the multitude of lightweight travel mounts and tracking mounts. Some look like scaled down versions of equatorial mounts (Skywatcher Star Adventurer, Bresser Astrophoto Tracking Mount, iOptron Sky Tracker), others have weird and wonderful shapes (Astrotrac), other are just little boxes (Vixen Polarie, MSM SiFo).

  They all sit atop a tripod (some may come with their own) and have one axis pointed north, and another that slowly rotates. This rotation counteracts the earth’s rotation so objects remain still through the camera view finder. Most will be battery powered for remote use, but think about spare batteries or a powertank. Like with a static set-up C1, a camera, lens, ball head and intervalometer are needed on top of the mount. Some of the more advanced tracking mounts may even control your exposures via a cable release and allow for some guiding (see below).

• What could I observe?

  You can now photograph pretty much anything, the limiting factor will be your camera and lens. Wide angle views will be improved with tracking (perhaps combined with a non-tracked foreground) and longer focal length will start to cross over into the realm of small refractors (except you don’t have the options of visual observing). If you already have good quality photography equipment and know your way around the settings, this will be a great way to use your kit in a new way.

• How complicated is it to use?

  Leaning to align correctly will take a few goes and you’ll need to find Polaris. Indeed if you have no view of the north star this technique is impossible I would say. Different mounts have ways to help; polar scopes (often extras not included), laser pointers etc. will help you get a decent enough fix on Polaris. Exposure length is worth experimenting with; there’ll be a point where stars start to trail so dial it back on the exposure length and go for stacking images to bring out greater detail and reduce noise. As ever, spend some time getting the focus right before starting an imaging run. If you’ll be using it remotely think about portability and whether a travel case is needed. Standard DIY toolboxes packed with foam are a low-tech way to keep your equipment safe and portable.

• Cost?

  In addition to everything in C1 or C2 plus a tracking mount will cost you £200-400 (check if tripod is needed too).

Read about my review of the MSM SiFo rotator here

Set-up C4 - Piggybacked camera onto a telescope

This set-up is become obsolete by C3 and assumes you already have the ability to track the sky with a telescope mount. Piggybacking simply provides a way to mount your camera onto the scope (either facing the same direction or looking elsewhere with a ball head). The addition of a camera adds weight that will change the balance of the scope considerably. That said, the development of new tiny cameras like the GoPro make this technique possible again - I have a GoPro bracket fixed to the bottom of my main imaging scope in case I wanted to run a time lapse whilst doing my main imaging. The GoPro can also be controlled via iPhone or even using vocal commands so ‘no touching’ required.

• What do I need?

  DSLR Piggybacking is done via rings, a dovetail plate or a bespoke bracket with standard photography threaded screw (found on the base of your camera body). The rings or plate must be compatible with your scope. GoPro uses a sticky pad with a clip-shoe.

• What could I observe?

  Same as C3. As you couldn’t observe at the same time (for fear of knocking the mount) this gives you visual OR photography, but not both at once. GoPro allows shooting video, or if you’ve popped inside, you could use it’s wifi link to check the clouds haven’t rolled in.

• How complicated is it to use?

  I tried DSLR piggybacking a few times and found it hard, probably because I was using a small scope and an equally heavy camera. A true piggyback should be a big scope and a small camera where the extra load and weight change is minimal, hence why a GoPro onto say, an 8” is a good fit.

• Cost?

  For true piggybacking you might need to spend around £50 on rings or some dovetail adaptors to match your scope and camera.

Set-up D1 - First telescope: Grab and Go telescope on manual mount

The classic ‘grab and go’ set-up is a small refractor that can literally be picked up, taken outside and be useful within seconds. It’s the kind of thing you can leave assembled on a mount so there is zero time wasted at the start or end of the night. It can be placed anywhere and point anywhere but is purely for visual observing. My first telescope was a small GoTo (see D2) and I reverted to D1 for two reasons; one, I wasting observing time setting up each evening and secondly, I decided to start buying individual items each of higher quality (the equivalent of buying a complete bike or making one from the best frame, best gears etc.).

• What do I need?

  Small good quality scope (normally a 60-80mm refractor or small 80-110mm Maksutov design) suited for visual use, diagonal, eyepieces and tripod. Also these scopes have fixed mirrors and do not require collimation (e.g. tuning up) which for a novice is an unnecessary complication. I would suggest a Alt Az manual tripod with handles to control the slow motion controls. The Vixen Porta II mount is a good example; lightweight but sturdy. I’d also recommend a red dot finder or finderscope to help you locate objects as you’ll be driving this thing manually. This is an ideal set-up to take away for trips as you don’t need powerpacks, cables and other astro stuff. It’s one for the purists!

• What could I observe?

  This is about the observing not photography, although you could probably grab a few short exposure of the Moon through an eyepiece. With the whole sky at your disposal, the limiting factor will be your scope and eyepieces, but should should expect to resolve cloud banding on Jupiter, see Saturn’s rings, Venus’s phases, open clusters and double stars. Small scopes do not have the light capturing power for fainter objects, so only the brightest (e.g. Orion Nebula) will give something to enjoy.

• How complicated is it to use?

  Very simply. The red dot finder will get you aiming correctly then its simply moving around the sky at your own pace. A zoom eyepiece is a good way to find objects (start at 24mm) then zoom in for more detail. Keeping it stripped down to the essentials is what makes this set-up a joy to use.

• Cost?

  Online shops probably do combos of this kind of set-up, but remember you’re paying for convenience; items purchased individually will be better spec, more expensive but last you longer. Your small scope now may become your guidescope for your future BIG telescope. Examples: good 70mm refractor £300-500, diagonal £30-200, eyepieces (individual from £30-250, Zoom EP £60-200), red dot finder £20, mount (say, Vixen Porta II c.£250). Kit combos: Vixen 110mm Maksutov on Porta II mount with eyepieces and red dot finder c. £500, or 80mm refractor, alt az mount, eyepieces, red dot finder (no diagonal) £170. I’m going to settle on around £500 for good quality and longevity.

Eyepieces / barlows and filters

If you are observing through a telescope you’ll need an eyepiece, or perhaps a couple to give different magnifications. Like camera lenses, eyepieces come in mm lengths (not their physical size) but the numbers are inverse to camera lens; so a 40mm eyepiece gives a wide low magnification view, a 3mm gives high magnification over a small area (a camera lens of 20mm is wide field, whereas as 300mm is telephoto). There are rules about far you can push the magnification of any scope based on aperture, hence the general antipathy to small, cheap telescopes boasting 300x magnification. Most scopes will come with stock lenses around 15-24mm which are fine but not high quality. A worthy investment would be a zoom eyepiece which rotates through different length from say 8-24mm. This avoids having to buy a loads of eyepieces and changing them over in the dark. Eyepieces can cost hundreds of pounds on their own and like camera lenses, you get what you pay for.

A barlow is a device that sits between your eyepiece and the telescope and doubles the power of the eyepiece, so a 20mm becomes a 10mm with a 2x barlow. They start relatively inexpensive and when used effectively give you twice as many eyepieces.

Filters are useful for visual observing and their main purpose is to draw out detail in what you are looking at. A Moon filter helps cut out the brightest areas so you can see better contrast on the lunar surface. Certain colour filters are good for planetary features like cloud formations on Jupiter or observing the Great Red Spot. They are not essential.

Diagonals and Prisms

Finally you need something to put your eyepiece in. A diagonal or prism sits between the scope and the eyepiece and directs the light to a more comfortable viewing position (otherwise you’ll be crawling on you knees to get a straight through view). There are a few variations based on the physical angle (45 or 90, or variable) and whether they offer an ‘erect image’. This is particularly important if you want to use a scope for terrestrial observing or bird watching - most telescope give an inverted view (where say left and right are swapped, or up and down is swapped). An erect image diagonal gives you a true L-R & Up-Down view. Like a good pair of binoculars. a good diagonal and good eyepiece can not only improve your astro observing but give you a versatile daytime spotting scope.

Set-up D2 - First telescope: Goto scope/ mount/ tripod combo

When choosing your first telescope there is a lot to consider. You want to buy something half decent that is not a cheap toy, will last you a few years and help you develop. Alternatively if you find its not for you, then you haven’t shelled out too much cash. You probably want something to give a good all-round coverage (stars, planets, bright nebula and the Moon) that is easy to set up and use. The old adage is that the best telescope is the one you use e.g. if its too difficult, heavy or complicated, you won’t get any use from it.

You’ll probably also need some help finding objects which is where Goto comes in. A Goto device has an inbuilt star catalogue, which once aligned and told where it is globally (lat/long, time zone etc.) will be able to ‘go to’ any object in the sky at the touch of a button. Most manufacturer’s have their own version of an inbuilt computer and hand controller but they are all doing the same thing; the database tells the motors where to slew to. Once they have found the object they will track it, untill you choose to move on. Some have GPS to help locate themselves automatically and others link up with your smart phone to utilise the more user friendly graphical displays you get in astronomy apps like Sky Safari. They are getting more sophisticated and user friendly, but you still need a little knowledge of the brighter stars otherwise how do you know its actually pointing at Vega?

• What do I need?

  Either a separate Goto mount and OTA (optical tube assembly = telescope) or a Goto combo (mount and scope together). Goto mounts tend to be either Alt Azimuth, fork driven or lightweight equatorial mounts. Alt Az and fork drive mounts (where the scope is clasped from either side) are better because they are simpler to use but have limitations for photography. The scopes themselves, like set-up D1 tend to be small refractors or those with ‘folded’ optics. These include Maksutov and Cassegrain designs where a relatively small (and fat) tube send light up and back to multiple mirrors to give a longer focal length in a smaller physical size. You’ll then need bits and bobs for the scope like eyepieces, diagonals etc. as mentioned above.

• What could I observe?

  Goto combos can go up to 10-12” which are big expensive scopes, but generally they’re around the 4-8” range for Cassegrains, 70-120mm for Makstuovs and refractors. (Note once you get above 150mm aperture it jumps into inches!) Comparing a 90mm refractor with a 6” Cassegrain, you get great views of the Moon craters, start to see detail on the brighter planets and get enhanced views of deep sky objects. Greater aperture means being able to see smaller objects, although they will still be small in the eyepiece and require some practice to observe them.

• How complicated is it to use?

  It probably sounds more complicated than it is but will need some practice. You could expect to take +30mins to get set up the first few times, hopefully getting quicker as you learn. Like anything computerised they are not fool proof or error proof; we have all be through nights where after three or four attempts to get the scope aligned the battery dies or the clouds roll in and you’re left thinking ‘why did I bother?’. You’ll need to accept there’s a learning curve and enjoy working through it. As mentioned above, Alt Az and fork systems are easier to set up than equatorial mounts and alignment for visual use does not have to be as accurate as for photography. YouTube is a great resource and I’m sure for any make and model there’ll be someone who can show you simply how it’s done.

• Cost?

  Packages: from around £300 for smaller apertures (70-80mm), 127mm around £400, 4” around £500, 5” around £700, 6” around £800 (using Skywatcher SkyMaz and Celestron NexStar as a guide. Meade also have a range of Goto scopes). You might get eyepieces within a package, otherwise don’t forget batteries/ power supply.

  Otherwise pair a quality OTA (£400-600 range) with a mount like iOptron Cube or Minitower (£500-800) similar checking the weight to ensure compatibility.

Set-up D3 - Goto Equatorial Mount

An equatorial mount is probably straying into intermediate territory as there is a little more complexity in the set-up procedure to allow greater tracking accuracy. German is the ‘classic’ EQ design used by Skywatcher, Celestron whereas iOptron have developed their CEM centre weighted design (see below). Unlike a fork-driven Goto where the unit is one piece, an equatorial mount and it’s scope will be separate (whether purchased together or not) giving greater flexibility over choice of mount and OTA. Once you get into intermediate range, the mount becomes key and you should probably invest more in this than the scope itself. A motor driven equatorial mount is still classed as Goto, owing to the inbuilt computer and controller, but I’d expect users of these mounts to have greater knowledge of the objects they want to observe and delve further into the menus for things like tracking speeds, guiding, Periodic Error Correction etc.

• What do I need?

  An equatorial mount and an OTA (scope), red dot finder (or finderscope), eyepieces, diagonal, barlow etc. Unlike more basic Goto mounts, these will not be battery powered so will need either a protected mains supply or a powertank.

• What could I observe?

  An equatorial mount will have a greater load capacity than an Alt Az mount, so larger scopes equals more light. The amateur range is typically 6”-14” but note for anything above 8-10” you need a chunky mount and plenty of £££. In scopes around 8” you will start to resolve the brightest galaxies, see detail in clusters and see great detail on the lunar surface. I have seen the shadows of the Jovian moons crossing the disc of Jupiter in an 8”.

• How complicated is it to use?

  Practising in the daylight will save you time in the dark. There will be various cables to connect so know what they all do and where they go. Polar alignment is the most complicated part but this is getting easier with new tech like the Polemaster (c. £250). A relatively recent extra is in-built polar alignment cameras like the iPolar, which added to in-build GPS helps take the pain and time out of set-up. Make sure you power is charged up as there’s nothing more annoying than missing a clear night due to lack of power. Factor in that from a standing start you may need 30mins or more before you start any astronomy (and time to pack away).

• Cost?

  Equatorial mounts with a good weight capacity start around £800-1000, rising to £1500-2500 as the weights increase. Bear in mind the top end semi-pro mounts cost £10,000. The more expensive mounts will have extra features and probably tighter tracking accuracy. EQ mounts give you the flexibility to swap scopes and upgrade in the future. 8” OTAs are around £800-1000, or you could consider a high quality small refractor (£700-1000) to pair with your EQ mount, which in a few years you can upgrade. Remember not all accessories fit all scopes. As people upgrade they sell off their kit, so you may get a secondhand bargain.

Types of Mounts

The mount is a fancy word for the tripod once it begins to have rotating axis and computerisation. A mount can be just a ‘head’ fixed to a permanent pier or a combined tripod and head - the main thing is it has to be stable, level and capable of supporting the equipment on top. There are a few basic designs:

Alt Az is short for Altitude and Azimuth, basically astronomical terms for the vertical height from horizon to zenith (the point above your head) and left/right. An Alt Az mount has controls for both; a manual mount will have turning handles that you can gently twist to follow an object across the sky for visual observing, or a computerised version will do the same with automation. Crucially this type of mount cannot be used for photography as the up/down left/right does not allow for the rotation of the object as it moves.

Equatorial (or German) is the most common mount comprised of two axis, Right Ascension (RA) and Declination (Dec). These mounts require polar alignment with the RA axis aimed at Polaris, usually done with the help of a polar scope and fine tuning adjustment of the head on top of the tripod. For this you need to know your latitude (your phone will tell you this). Some mounts also have GPS support; so having fixed the latitude, north direction and precise time, the on-board computer (controlled with a hand controller) should help you find any of the 30-40,000 objects in the mount’s directory. If you don’t have a fixed set up, this procedure must be done from scratch each time, which I personally found a huge motivation to building a permanent observatory.

CEM (or Chinese equatorial mount) is a variant on equatorial, also has two axis, RA and DEC, but claims a closer centre of gravity. Another benefit is that polar alignment can be constantly reviewed as the polar scope view is never blocked. iOptron have made this design their own and have a range of load capacities from lightweight to observatory level.

All mounts use counterweights to balance the telescope (and paraphernalia on top). Achieving balance on both axis means the tracking is smoother and your not overpowering the motors. Beware of load capacities stated by manufacturers - they are notoriously over confident and you should probably only take 2/3rd of any max. load claim for granted for photography work - you don’t want the mount working right on it’s limits.

As soon you get into computerisation with mounts you need power. From this point cable management becomes important. External powerpacks are popular but eventually degrade over time. A long extension lead from the house could work, but keeping it (and you) safely protected against moisture and tripping in the dark are important. Most stuff goes of 12v which may be a small power lead or cigarette type socket. Find what works for you.

Set-up AP1 - DSLR Astrophotography through telescope - unguided

Assuming a D3 equatorial mount and OTA (see above) photography is often the next step as you have a stable mount capable of both finding objects and tracking them. The type of scope (aperture, focal length and f ratio) will determine whether you’ll be taking wide shots or very narrow fields of view. You then need to add a camera, usually a DSLR body using a T-ring (a standard thread for telescopic equipment suited to your camera e.g. Canon T-ring or Nikon T-ring) and a nose piece that replicates the eyepiece.

• What do I need?

  As D3, an equatorial mount with a good load capacity, OTA, camera and means to connect it (T-ring, adaptors). The accuracy required for photography is greater than for visual observing, so don’t push the loading of the mount too far, and don’t trust the stated maximum.

• What could I photograph?

  Anything you want now you have a stable set-up. The size and brightness of the objects become important. Using apps like SkySafari you can enter you equipment (aperture, focal lengths, camera type) and it will give you a field of view box overlaid on the star field. You can use this to decide on good photography targets and see which objects you can group into the same frame. Your mount will track objects (see below for guiding). The scope aperture and your location will give you a limiting magnitude for fainter objects. Although you now have a great set-up - don’t confuse it with Hubble.

• How easy is it to use?

  Assuming you’re familiar with the mount set-up, then its just the camera controls to get used to. Practising by day saves cable fumbling by night. Always run some test exposures before running off too many images and always check your focus carefully. Through trial and error, find the right length of exposure that works for your mount without too much noise or light pollution.

  A Bahtinov Mask is an essential (and relatively inexpensive) tool for focusing accurately and very quick to use. Placed over the end of the scope, it produces a defraction pattern that changes in and out of focus so you know when you are perfectly in focus.

  Note that the weight of a camera may exceed your normal visual assembly, and accurate photography requires good balance. Check this with the full camera load to ensure the mount gears and not fighting against the weight of your accessories.

• Cost?

  In addition to D3, T-rings around around £20, similar for Bahtinov Masks. Astromony apps - some are free, others with more features pay £5-10.

Attaching a Camera

There are various ways to attach a camera to a telescope, each giving different results.

Prime focus is where you attach a DSLR body via T-ring and nosepiece into the telescope focuser. The only ‘magnification’ involved is the focal length of the OTA and you are effectively using the scope as a lens on the camera body. Finding focus the first time can be hard and it’s possible you may require extension tubes or adaptors to achieve focus as the natural point where the image is resolved (back focus) is a long way behind the back of the telescope. You can test this in the daytime on distant objects, and remember that without your visual diagonal or prism, the image may be inverted.

Afocal photography involves placing an eyepiece between OTA and camera lens. This could be simply done by holding the camera up to the eyepiece - but try it, its not that simple! Special adaptors can be clamped to the body of the eyepiece then you attach your smartphone or compact camera and using fine tuning knobs, you find the sweet spot over the eyepiece.

Eyepiece projection is to thread a DSLR body directly onto a eyepiece (or via a holder tube). More expensive EPs like the Baader Hyperion range have threads on the top to attach to a T-ring. Now the EP is acting like the lens and giving extra magnification. Like afocal, this is a good way to ‘capture what you see’ and may give good snaps of the Moon or brighter planets. It is quite limited as a technique.

Flatteners and reducers. It is likely that with prime focus it will exaggerate the natural ‘errors’ in the scope; the stars at the edge may be blurry or warped, fringe colours appear etc. This happens naturally due to the light passing through lenses or between mirrors. Remember some telescopes are designed for directing light onto a curved eyeball, which is totally different to those designed for focusing onto a flat camera sensor e.g. astrographs. This is why for photography, many scopes are paired with (indeed often sold with / recommended) a field flattener or focal reducer. When paired with the right scope (usually based on f ratio) they will iron out any errors in the image to achieve greater consistency of star shapes and colour. Note unlike a field flattener, a focal reducer will change the focal length by say 0.75x or 0.6x giving a slightly wider (less zoomed) view but reducing the f ratio (to make the scope faster). Field flatteners and focal reducers sit in the image train between OTA and camera and there will be a specific distance or ‘sweet spot’ from the back of the reducer to the sensor on the camera. Therefore spacer rings of different sizes are used to achieve the perfect distance.

Filters can also be placed in the image train; some are clips that sit into the camera body, others screw into the threads on the flattener or reducer. Photography filters differ to visual filters but can be used to bring out greater contrasts, reduce the effects of light pollution or only allow light captured in very specific frequencies (narrowband filters).

Set-up AP2 - DSLR Astrophotography through telescope with guiding (laptop)

First an admission - I’ve never done this. I never had a laptop that I wanted to use outside in the cold/dark adding to my power and cable management issues. It is however the conventional way to do guiding and those who do it do it very successfully. A laptop can not only control your guiding software (talking to your mount’s motors) but also run other software for image capturing, polar alignment etc.

• What do I need?

  In addition to everything in the AP1 list above, you’ll need the means to do guiding: guidescope connected to the main OTA, guide camera, laptop and software. Most astronomy software is Windows based, so a PC is more versatile than a Mac.

• What could I photograph?

  Changing to guiding doesn’t affect what you can photograph, it just gets you better results. Even with accurate polar alignment, good balance and a well tuned mount, you’ll still get small tracking errors that will show in long exposures. Guided subs over over 60sec is where you’ll really see the difference. You regularly see impressive images in magazines with 5 or even 10min subs, which are impossible without guiding.

• How easy is it to use?

  Ask someone who’s done it! What I will say, is that having got used to your mount, scope and their settings, introducing a laptop and software introduces a whole world of settings, menus and sliders. Don’t forget why you’re out there - to look at the stars.

• Cost?

  Guidescope c. £100, maybe an adaptor or rings to secure it (c. £50-100), guide cameras from c. £150 + PC + software (capturing software probably comes free with camera).

Set-up AP3 - DSLR Astrophotography through telescope with standalone guiding

For those with an aversion to laptops there is an alternative. A handful of guide cameras can work without a computer as they have their own. The LVI Smartguider is one of a few examples that are a kit comprising camera, controller unit and all necessary cables. Newer kids on the block are the ASIair or Primaluce Eagle which are mini computers that ride on the mount and use smartphones/PC as the interface, with the added benefit of also controlling the main imaging camera, filter wheels, auto focuser etc. These new controller boxes are small and light to help keep weight down and increase portability.

• What do I need?

  Everything in AP2, but ditch the laptop. Standalone guide camera pack or an interface like the ASIair that can talk to your guide camera and smartphone (check compatibility between cameras and interfaces).

• What can I photograph?

  Same as AP2

• How easy is it to use?

  I used a LVI Smartguider II for many years and really struggled with it. I bought it secondhand, and probably in the 3 years I used it I spent more time fighting it than guiding with it. Hence when I got my ASIair and ZWO guide camera it was a revelation - not only doing guiding but also helping with other issues like plate solving.

• Cost?

  ASIair is a very reasonable £170. Remember this needs power, so you might need a few more leads or adaptors to get everything connected up. App to run it is free. The Primaluce Eagle is a different beast c.£1000 but (as I understand it) acts as a power hub, can control dew heaters (and more) becoming the heart of your set-up. It drives all your other accessories, so it is basically replicating what a laptop does in a smaller, more convenient package.

What is guiding?

Guiding is for intermediate and advanced imagers and is used to give longer exposures without star trailing. Most astrophotography involved the stacking of numerous images to draw out detail. Each individual image is a ‘sub’. A 1 hour exposure may be made from 60x60sec subs, or 30x120sec subs. From any session a number of subs will get rejected (poor tracking, satellite trails, planes etc.).

Even a well polar aligned scope will struggle to do more than a minute or so without showing some minor trailing. Guiding ensures exposure of 2, 3, 5 mins are usable with crisp, round stars. To do guiding you need a computer driven mount with a guide port. The guide camera is connected to the mount via a guide port using standard protocols meaning there should be compatibility between most cameras and most mounts. ST-4 is the common plug interface similar to a computer data port. Software then controls the read out from the camera and sends messages to the mount - left a bit, right a bit….all the while your main camera is taking subs. A smooth guiding graph shows minimal adjustment on the mount axis meaning greater chance of good images.

There are two main ways to do guiding; with a guide scope or off-axis guiding.

A guide scope is attached to your main scope and with the aid of a guide camera, talks to your computerized mount to make tiny corrections to the tracking. To do this it locks onto a guide star within the field of view. There is a calculation to be done to ensure the focal lengths of the primary scope and guide scope are within range to be effective. Most guide scope tend to be in the 30-60mm aperture range covering most amateur main scope apertures up to 8-10”.

Off-axis guiding (OAG) has no separate scope. An OAG is a ring placed on the image train between scope and imaging camera. The OAG has a small light prism that drops down into the image train (outside the view of the main camera) to deflect a small portion of light off into a guide camera. This guide camera works in the same way for a guide scope. The benefits of OAG are that the view of both cameras is the same source, and any deviations or ‘flexure’ between the main scope and guide scope are eliminated. It is however renowned for be being fiddly to get set up with both main and guide camera in focus simultaneously. OAG kits tend to come with a selection of spacer rings to help with this. Testing simultaneous focus is an exercise best done in daylight. I am starting to experiment with OAG and can confirm it requires both patience and practice.

Set-up E1 - Permanent pier

Everything up to AP3 involves some setting up and packing away per session, even if its just lifting your kit indoors. Of course any time spent carefully aligning and levelling your mount is lost when you move it, so the first 30mins of your next session is getting back to where you were. A away to avoid this is with a permanent set-up, which normally means an observatory, but a halfway house is a pier. A pier can either be a purchased item (generally a very chunky tripod or a steel tube), or constructed from concrete, steel or timber. On top of the pier you place your mount head using an adaptor plate (noting that each mount has a unique arrangements of holes and bolts for adjustment) to ensure you can get the mount aligned north and level.

• What do I need?

  Firstly pick a good site for your pier in order to maximise your view of the sky, ideally away from street lights or neighbours security lights. You may not have too much choice unless you have plenty of garden space. I picked my pier location specifically for very low views to the south, which my observatory cannot achieve. If you are DIY-minded then you might be able to knock something up, or else purchase the necessary components. The main thing is has to be rock solid or there’s little point doing it.

• What can I photograph?

  Hopefully the same as before, just a little quicker!

• How easy is it to use?

  This depends how much equipment you leave in position. Given your mount may be more expensive that your scope, you may not feel comfortable leaving it outside unless it is secure and protected from the weather. If the mount head is in place, you still need to add counterweights, scope, power it up and connect your cameras, so there is still some set up time. Hopefully though, alignment is sorted as you can align your mount head once then ‘park’ it, so when it reawakens, it should retain its alignment data.

• Cost?

  A field tripod pier is around £800 but is not ideal as it still has legs to avoid in the dark. A straight up post is better, like the Altair Astro Pier at £500 that requires you to construct a small concrete pad. This pier has an adjustable head so there’s no pressure on getting the pier set perfectly level and true - it can be tweaked later. My low cost pier project utilises a timber post and driven spikes but is of course not as solid as steel and concrete. I have also seen examples with concrete cast into large section drain pipes and using hollow concrete blocks stacked vertically. Don’t forget a heavyweight waterproof cover too, either an astro one or perhaps a heavy BBQ cover.

Set-up E2 - Observatory

The ultimate astronomy upgrade is the home observatory. It is not only about having a dedicated space to enjoy your astronomy but also allows your equipment to be left insitu, thereby minimising the set-up time to a few minutes. There is also the added benefit of having some comforts; protection from the wind, mains power for astronomical & non-astronomical devices (radio, lighting…), some storage, a chair etc. It’s fair to say that people don’t start astronomy with an observatory, they do it for a number of years, assemble various bits of kit and then think about a permanent home for it all.

I have written a blog about my experience of designing and building my home observatory and it has made a huge difference to the amount of astronomy I have done since and greatly increased my enjoyment when doing it.

Things to consider are placement of the observatory, whether to self-build or purchase, the pier (and base), power supply, securing and weatherproofing. You may not be able to see the whole sky from your garden so pick your best horizon, trying to get as much southerly aspect as possible for northern hemisphere observers.

There are a few common designs for small home observatories; domes & roll-off roof sheds being the main two. A dome would be very difficult to self build so these tend to be products like Pulsar, NexDome or SkyShed Pod. Roll-off roofs are far more shed like, so can be off the shelf or adapted form traditional sheds. There is plenty of information online so do your research and use existing precedents.