Tips for Buying Astronomical Equipment
Thinking of investing in some form of astronomical equipment? There is now a huge and bewildering selection of items to choose from so click here for are a few thoughts and tips, which may be of assistance in avoiding unnecessary pitfalls.
If you are buying a telescope first ask yourself a few questions. Who is the scope for? Is it intended purely for astronomical purposes? How serious are they? Is portability an issue? And what is the budget? Of the different types of scope, bear in mind that a reflecting telescope; one that employs mirrors, is solely used for astronomical purposes. Reflecting telescopes have the eyepiece and focuser positioned near the top end of the tube, in line with the secondary mirror, which is housed just inside the open end of the tube.
A refractor (objective lens at one end and the eyepiece at the other) may be utilised for terrestrial viewing as well as astronomical, however when used for terrestrial purposes the image is often flipped so that writing looks reversed. A third design which has become increasingly popular is the Catadioptric such as the Cassagrain design. These are a sealed system (like a refractor) but employ a combination of mirrors and lenses to fold the optical light path. Cat’s are compact and portable (up to a point) but more expensive. Many scopes now employ GOTO technology which allows the user to observe any object in the system data base once set up, the key word being ‘once’. I would steer clear of small and apparently cheap GOTO instruments; from my experience they have limitations.
Basic entry 60-80mm refractors or 100mm (4inch) reflector’s can be purchased for as little as £70 - £120. Better quality refractors start from £200 and more robust 110mm (4 ½ ) and 150mm (6inch) reflecting scopes from £180. The most cost effective type of astronomical scope is the Dobsonian reflector; they are simple to set up and can be picked up for as little as £150 for a 150mm (6”) aperture – an excellent buy.
Perhaps a telescope may not be a viable option as a gift; however a pair of binoculars may be the perfect solution, providing a portable means of enjoying both the beauty of the heavens as well as our terrestrial surroundings. When choosing binoculars intended primarily for astronomical purposes; especially for a younger person, look for an eyepiece to objective ratio of roughly 7, such as 7 x 50 or 8 x 56, which matches the diameter of the eye pupil. This ratio becomes less critical for terrestrial viewing or for anyone over the age of 40. Look also for binoculars that employ BAK 4 prisms, these have multi coated surfaces. Expect to pay around £30 - £70 for an adequate pair of 7 or 10 x 50 binoculars and £90 - £250plus for something more refined. Larger models such as 11 x 80, 20 x 100 etc start around the £150 mark but will need to be mounted on a tripod to use satisfactorily.
If you are not tied to a budget, but like the portability of binoculars, consider a pair of image stabilizing binoculars, these counteract the effect of hand shake and can really enhance a viewing experience. Expect to pay anywhere from £280 to over £1000 depending on size and manufacturer.
If you are still unsure and require further guidance please contact me.
Mark Dawson, Whitby & District Astronomical Society, email: spanton33@talktalk.net
If you are buying a telescope first ask yourself a few questions. Who is the scope for? Is it intended purely for astronomical purposes? How serious are they? Is portability an issue? And what is the budget? Of the different types of scope, bear in mind that a reflecting telescope; one that employs mirrors, is solely used for astronomical purposes. Reflecting telescopes have the eyepiece and focuser positioned near the top end of the tube, in line with the secondary mirror, which is housed just inside the open end of the tube.
A refractor (objective lens at one end and the eyepiece at the other) may be utilised for terrestrial viewing as well as astronomical, however when used for terrestrial purposes the image is often flipped so that writing looks reversed. A third design which has become increasingly popular is the Catadioptric such as the Cassagrain design. These are a sealed system (like a refractor) but employ a combination of mirrors and lenses to fold the optical light path. Cat’s are compact and portable (up to a point) but more expensive. Many scopes now employ GOTO technology which allows the user to observe any object in the system data base once set up, the key word being ‘once’. I would steer clear of small and apparently cheap GOTO instruments; from my experience they have limitations.
Basic entry 60-80mm refractors or 100mm (4inch) reflector’s can be purchased for as little as £70 - £120. Better quality refractors start from £200 and more robust 110mm (4 ½ ) and 150mm (6inch) reflecting scopes from £180. The most cost effective type of astronomical scope is the Dobsonian reflector; they are simple to set up and can be picked up for as little as £150 for a 150mm (6”) aperture – an excellent buy.
Perhaps a telescope may not be a viable option as a gift; however a pair of binoculars may be the perfect solution, providing a portable means of enjoying both the beauty of the heavens as well as our terrestrial surroundings. When choosing binoculars intended primarily for astronomical purposes; especially for a younger person, look for an eyepiece to objective ratio of roughly 7, such as 7 x 50 or 8 x 56, which matches the diameter of the eye pupil. This ratio becomes less critical for terrestrial viewing or for anyone over the age of 40. Look also for binoculars that employ BAK 4 prisms, these have multi coated surfaces. Expect to pay around £30 - £70 for an adequate pair of 7 or 10 x 50 binoculars and £90 - £250plus for something more refined. Larger models such as 11 x 80, 20 x 100 etc start around the £150 mark but will need to be mounted on a tripod to use satisfactorily.
If you are not tied to a budget, but like the portability of binoculars, consider a pair of image stabilizing binoculars, these counteract the effect of hand shake and can really enhance a viewing experience. Expect to pay anywhere from £280 to over £1000 depending on size and manufacturer.
If you are still unsure and require further guidance please contact me.
Mark Dawson, Whitby & District Astronomical Society, email: spanton33@talktalk.net