By Adrian Ashford

Finders

When used at medium to high powers a telescope will show you only a small window on the sky. This can make finding faint objects a frustrating process without the aid of a finder. As the name suggests, these are observing aids that assist you in locating celestial objects, and all scopes — irrespective of type or design — should be equipped with one. In their commonly encountered form they resemble a miniature scope attached by a bracket close to the eyepiece of the main instrument. They have low magnifications with wide fields of view and are equipped with cross hairs (reticles) at the focus, like a gun sight. If it's correctly aligned with the main scope, centring the object in the finder gets it in the big instrument. Look for finders with apertures (front lenses) larger than 25mm wherever possible — larger finders give brighter images, making faint objects that much easier to locate.

A popular variant is the "laser" or "reflex" sight, which projects a point or ring(s) of light against the background sky. Many people prefer this intuitively simple option, but you're limited to naked-eye objects because this type of finder has no magnification. You can, however, still 'star-hop' from naked-eye targets to deep-sky objects.

Can I Photograph What I See?

Assuming you've bought a new scope, it's almost inevitable that you'll wish to use it to capture the beauty of a planetary image on film or to emulate the marvellous gallery of deep-sky photographs that grace Australian Sky & Telescope. In principle there's no reason why you shouldn't be able to, given the necessary equipment and inclination. But it's wise to take time to get used to operating your new scope and learning your way around the sky before embarking on an astrophotographic adventure.

Photography of the heavens can be incredibly rewarding, but it's more akin to an art than a science. The learning curve can be steep, and the equipment required can get expensive. While any telescope will permit you to take an image of the Moon, for just about everything else you'll need a scope on a very rigid, well-engineered, and precisely driven mount to be successful.

Everything Has Its Price

While it may be tempting financially, resist the urge to buy the cheapest telescope available. Many of these instruments are of poor quality either optically or mechanically (and frequently both) and will inevitably lead to disappointment. If you've a budget of less than $300, consider really good binoculars instead.

That said, there are a great number of quality instruments that can be obtained secondhand that an experienced member of your local astronomical club may be prepared to check out on your behalf. Or have you considered building one yourself? If you're gifted with your hands and enjoy working in wood, then it's quite easy to buy the optics and make a quality Dobsonian reflector yourself. Again, members of your local club will be able to help you with the details of construction.

Even if you're a beginner fortunate enough to have a sizable disposable income, do not buy the largest, most expensive telescope you can find. If you're just learning to identify the constellations, then many of the advanced features that such instruments possess are not likely to be of any use to you. It's also well worth remembering that there's more to a telescope than the tube assembly, mount, and tripod. Be sure to save some of your budget for additional eyepieces to expand the scope's magnification range, filters for combating light pollution and enhancing nebulae and planetary images, and any number of other available accessories — particularly for astrophotography.

Concluding Thoughts

So is there a perfect telescope out there just waiting for you? Actually, there is — it's the one you'll use most often! An optically perfect but massive refractor will be effectively useless if you can't carry it outside, and the largest Dobsonian will not show you the faintest galaxies if the only place you can use it is a light-polluted parking lot in the centre of a city.

Consider carefully what you feel to be your primary observing interest, where you're likely to be able to observe, and what constitutes "portable" to you. Remember that each telescope has its own strengths and weaknesses — an ideal instrument for detecting fine detail on the planets may not be the best at catching ethereal wisps of light from distant galaxies.

Visit your local astronomy club, which will often have observing nights when you can use various scopes and chat with their owners. A telescope is a big investment to most people, and the universe is not going away, so take your time over the purchase. When you buy the instrument that's right for you, you'll possess the key to unlocking a universe of wonders. It's a clear night — what are you waiting for?