Telescope Accessories Guide
If you are reading this, you have most likely purchased a telescope or are looking to get one. Regardless of which category you fall under, this guide will provide you with a comprehensive overview of which telescope accessories and upgrades you might want to consider for your new telescope.
In this guide we hope to show you that there are many ways of improving a telescope’s capabilities and that getting the most out of your telescope is easier and cheaper than you might think. From filters that enhance your celestial and planetary observation to collimators that give you that extra step of precision, this guide will enlighten you about the purposes and benefits of telescope accessories so you can get the best from your first steps in astronomy.
Telescope filters may be one of the easiest and most useful accessories that you can add to your kit. There are many types of filters including, but not limited to, light pollution filters, moon filters, solar filters, colour planetary filters, and nebula filters. Astronomy filters are largely categorised as 'broadband' or 'narrowband' filters. While there is such a vast range, the underlying principle remains the same – filters work by rejecting particular wavelengths that correspond to unwanted light sources that have been scientifically identified so that you only see crisp, clear and bright images.
Colour Planetary Filters
Colour Planetary Filters are broadband filters that work by rejecting colours from particular wavelengths in the visible spectrum so that your view will have better contrast through accentuation and disattenuation of important wavelengths. For example, a red colour planetary filter will disattentuate the wavelengths associated with the red colour along the visible spectrum and accentuate the rest. This in particular will be extremely helpful for viewing planets such as Mars, Jupiter and Saturn.
Basic Colour Planetary filter kits commonly consist of red, yellow, blue and neutral planetary filters. However there is a wide range of individual colour planetary filters that suits different needs that can be purchased individually. It is important to note that individual colour planetary filters are identified through a system known as wratten numbers (eg. #23A (red) and #80A (blue)) and its suitability depends on the aperture of your telescope. It is recommended that the smaller diameter of the objective lens of your telescope, the more visible light transmission from the filter you would want.
Solar and Moon Filters
Solar filters block out excessive brightness and heat from the sun to protect your eyes from damage while observing the Sun. Moon Filters, on the other hand, work to reduce the brightness of the moon, leaving you with clear view of moon craters and other interesting lunar landmarks. These filters are most useful for when observing the Sun and the Moon, respectively. In particular, solar filters must always be used when observing the Sun. This is due to the fact that telescopes are designed to gather light, and gathering light from the Sun which emits an enormous amount of light would undoubtedly damage your eyes. A solar filter would counteract that issue. An alternative to a solar filter would be solar safety film which has the same utility and price but requires you to make your own filter.
Light Pollution filters
Light Pollution filters are designed for astronomy enthusiasts living in urban areas with excessive amounts of light pollution. Artificial light sources may disrupt your viewing experience by adding unwanted brightness into your view. These distractions can be reduced by installing filters that reject wavelengths that corresponds to artificial light. Those who have used light pollution filters have heavily praised them and they are expected to continue to be a favourite for those living in light pollution areas or those who want to further enhance their telescope in dark site areas.
Narrowband filters work as the name suggests – they allow for a narrow segment of wavelengths from the visible spectrum, making them robust against light pollution and effectively improves the details of planetary nebulae in the night sky. More specific filters such as the Oxygen III Filters are useful if you have specific celestial or planetary objects you wish to observe – for example, the Oxygen III Filters are ideal for observing planetary nebulae as the portion of wavelengths allowed was especially designed this way. The most common narrowband filters are Oxygen III (O III), Hydrogen Alpha (Ha) and Ionised Sulfur (SII).
Telescope Eyepieces and Adapters
There is a wide variety of telescope eyepieces and adapters with very different purposes. They generally come in two universal sizes so you need to consider which size of eyepiece you require before making a purchase: 1.25″ and 2″. Eyepiece adapters are useful for those who want to switch from a 1.25” to 2” eyepiece size and vice versa. There are advantages of using a 2” eyepiece size, for example, 2” eyepieces tend to have a wider field of view, however it depends on the manufacturer and make of the eyepiece.
One method of determining whether the field of view will widen with a 2” eyepiece would be comparing the ‘actual field of view’ specifications with a reference 1.25” eyepiece (commonly the one you are currently using). There are also other considerations such as the specifications of the telescope and its suitability for eyepieces. Some telescopes may strive on or only support a 1.25” eyepiece whereas more advanced telescope models would suit and excel with a 2” eyepiece.
A Barlow Lens is the ultimate best friend for almost all astronomers. Barlow lenses generally come in either 2x or 3x magnification and increases the magnification of your eyepiece by that amount. This allows you to see further away in a drop of a hat and at a low cost. You do not need to get a new telescope just for a greater magnification, and you certainly do not need to break the bank.
Erecting Eyepiece and Erecting Prisms
Due to the use of mirrors in their design, reflector telescopes and catadioptric telescopes produce images that are upside-down or flipped. An erecting eyepiece or erecting prism (aka. erect image diagonal) will eliminate this entirely. With an erecting eyepiece or prism, you can see the world right way up in the correct orientation, making this accessory perfect for people who want to use their telescopes for terrestrial viewing. It is also important to differentiate between erecting prisms and erecting eyepieces as they do the same job in different ways. Erecting prisms can be described as an adapter that uses an internal mirror to flip the image and creates an angle (usually either 45 or 90 degree) and fits in between the eyepiece and the telescope. Erecting eyepieces, on the other hand, uses a relay lens to flip the image without the need for the introduction of an angle. The main consideration when purchasing an erecting prism or eyepiece would be the angle you would like to use your telescope at, generally with a refractor telescope you will need an angled prism but with a reflector you may wish to consider the erecting eyepiece as an option.
A Star Diagonal is an accessory that is attached to the eyepiece and allows the observer to view from a 90 degree angle to the telescope’s eyepiece. This is particularly useful when observing an object that is overhead of the observer and reduces neck strain.
A Zoom Eyepiece is an extremely convenient accessory that allows you to alter the telescope’s magnification without changing your eyepiece. These are a must-have for those who would prefer not to switch eyepieces when they want to increase or decrease the magnification or if they would like to see the granular differences in between each magnification.
Changing your stock eyepieces to Plossl eyepieces will bring vast improvements to the viewing quality. Plossl eyepieces are arguably an upgrade to your telescopic gear because its composition is designed to create a wider field of view and better image quality than standard eyepieces. However, the design comes at the cost of a lower eye relief which may make Plossl eyepieces less appealing for some.
If you happen to want to observe with an even wider field of view than with a Plossl eyepiece, getting a wide angle eyepiece may be your best option. Compared to Plossl eyepieces that average an apparent field of view of 50-52°, wide angle eyepieces can yield an apparent field of view of up to 82°. Wide-angle Eyepieces are available in both 1.25” and 2” barrel sizes.
60° FIELD OF VIEW
68° FIELD OF VIEW
82° FIELD OF VIEW
Celestron Luminos Eyepiece - 2-inch - 23mm
Due to the presence of lenses in telescope eyepieces, regular eyepieces may be subject to chromatic aberration and disrupt your view. This manifests as discolouration, blurriness or graininess of the view towards the edges of your view. ED Eyepieces (ED stands for extra-low dispersion) essentially eliminates the possibility of chromatic aberration, leaving you with only clear and bright images.
Eyepiece and Filter Kit
Some brands offer Eyepiece and Filter Kits that incorporate a nice spread of eyepieces with varying focal lengths (to produce different magnifications) and telescope filters to target different uses. For beginners who want to do a bit of everything, these kits are a budget-friendly manner of getting eyepieces and filters bundled at a discount price with little research required! They also come in an accessory box for convenient storage and protection. Some bundles even include a barlow lens that will double the magnifications of all the eyepieces that come with it!
While changing your telescope mount is a much pricier upgrade, it offers a plenitude of improvements in terms of viewing quality and functionality. A simple azimuth (AZ) mount is the most basic of the mounts and offers no additional functions other than physical support. An improvement to that mount would be securing an equatorial (EQ) mount which outshines the azimuth mount with its ability to counteract the Earth’s rotation. This would be extremely helpful for astrophotographers or those who want to gaze at a celestial or planetary object for longer periods of time in which the object must stay in the line of sight. The more advanced telescope mounts add on even more functionality by incorporating various computer systems into its design: Computerised Go-To AZ and Computerised Go-To EQ mounts. These computerised variations enable more prolonged tracking of the celestial or planetary target as well as helps you find other celestial objects within the hemisphere based on the information you have given. Needless to say, this is an amazing addition to your gear if you have just started out in astronomy.
Telescope DSLR Camera Adapters
A set of telescope DSLR camera adapters is a must-have for amateur astronomers hoping to get into astrophotography. Also known as a T-Adapter, telescope camera adapters connect your DSLR camera (through a T-mount) to the eyepiece of your telescope so you can take amazing photos from your telescope and store them permanently. This means that you can revisit the perfect scene and show your friends and family whenever you want. Make sure you get both parts and correct ones designated for your telescope- a T-adapter and a T-Mount designated for your camera model.
If you want to get started in planetary or lunar imaging, you may want to look into astro-imaging cameras. An astro-imaging camera allows you to take images from your telescope, view and store them on your computer through a USB cable. Historically, astro-imaging cameras, or CCD (charge-coupled device) cameras to be exact, have always been a high-end accessory with pricing in the several thousands of dollars, but with advancements in imaging sensors you can now purchase a CMOS (complementary metal-oxide semiconductor) Astro-Imaging camera for under a thousand dollars making them cheaper than the cost of a conventional DSLR camera. CCD Cameras are still the industry standard when it comes to astrophotography and the price reflects that, however with the advancement of CMOS cameras you can now have a camera that although not as powerful as a CCD camera will still offer significantly improved imaging of the night sky. In a nutshell, CCD cameras are more expensive due to their design, however they yield images of higher resolution and brightness. Whereas CMOS cameras offer similar functionality without the spiraling cost!
For more details on selecting an astroimaging camera, check out our Astronomy Camera Buying Guide.
Finderscopes are extremely useful for locating your target object before looking at it closely through the telescope. This is possible due to their lower magnification and wider field of view which allows you to see more of the night sky than you would through the telescope. There are a few ways in which you can upgrade your finderscope. There is the option to purchase a finderscope with a larger magnification and aperture to see deeper into the sky. You may also benefit from purchasing a finderscope with an illuminated reticle or crosshairs that enhances your precision when aiming your telescope at night. Finderscopes are also available in right angle or 45 degree erecting designs that are ideal for observing objects that are directly overhead of the observer. Erecting finderscopes may be used alongside erecting prisms in order to reduce neck strain in these circumstances. Some finderscopes may incorporate two or more of these features so it is best to pick and choose which features you want before settling down on one!
Motor drives would make tracking of objects with a basic Equatorial (EQ) mount much easier. With a polar aligned equatorial mount, basic equatorial mounts may require you to manually move your telescope to keep your object in view. However, motor drives would do that automatically at the preset time intervals so you do not have to do a thing after aligning your telescope. This means that your sole concentration will be on the good stuff – the view!
As the sky is filled with many faint celestial objects, exposure time on a DSLR camera may be astronomical if using a wide aperture and wide-field of view telescope. This exposure time can be dramatically reduced using a focal reducer. This accessory allows the telescope to operate at two focal ratios and the opportunity to sidestep that flaw. This means you can get high resolution astrophotography without any loss in quality, faster! Be careful though, there are specific focal reducers for your telescope so make sure you do your research before buying!
Collimation has often been regarded as a complex, chore-like process that is required to maintain a telescope. It is vital to the upkeep of your telescope as over time, a telescope’s internal mechanisms will drift away from optimum setting and will gradually disrupt your telescope’s capacity to produce beautiful views. Using accessories, the process is simplified and you can turn your telescope back to perfection in no time. Some options of collimating accessories that are available are cheshire collimators and laser collimators. The cheshire collimator uses a peephole and bright colours to simplify the process whereas laser collimators use a laser pointer, respectively.
saxon 1.25-inch Cheshire Collimator Eyepiece
Another popular accessory is a Powertank which is only applicable to those with a computerised telescope. This is essentially a 12V external battery that you can use to power your telescope away from home. If you generally use your telescope at home or close to a mains power supply, then you can absolutely use a 12V mains adapter instead.
Smartphone adapters is a relatively new but extremely popular accessory for beginners. With a smartphone adapter, you can adapt your phone's camera to your telescope's eyepiece to take pictures or simply view your telescope's view on your phone's screen instead. Great for families who don't want their kids to touch the telescope or for beginner astrophotographers who don't want to spend loads on a DSLR or astroimaging cameras. Some smartphone adapters even have bluetooth dongles for you to take images remotely!
This guide has pretty much summarised all the accessories you may want to consider getting for your telescope. While there are many of types of accessories, it is best to consider what you want most out of astronomical viewing and get the accessories that will best cater for that.
If you have any questions about what you have read today or if you would like some help with choosing the right accessories to suit your needs, please don’t hesitate to email us at email@example.com or call us at 1300 884 763.