- Observational Astronomy
- Getting used to the Dark - Eye Adaption
- Binocular Astronomy
- Light Pollution
- Why do Stars Twinkle?
- How do I take Long Exposures with my Canon DSLR?
- How to Photograph the Moon with a DSLR
- Buying Your First Telescope
- Your First Night With Your First Telescope
- Sky Orientation through a Telescope
- Polar Alignment of an Equatorial Telescope Mount
- Astronomy Filters
A quick browse through various astronomy shopping websites will quickly show a wide range of good quality telescopic equipment available to purchase. For the beginner setting out to explore the sky for the first time and faced with this daunting choice, perhaps the best option before taking the plunge is to start small, or better still, learn one's way around the sky with a pair of binoculars before moving onto a larger, more powerful instrument. Even if you do invest in a large aperture telescope, a pair of binoculars still comes in handy for low magnification reconnaissance of deep sky targets before bringing the telescope to bear.
Portability is a big factor in binoculars favour. It's easy to move to a dark unobstructed spot for a view of something low down with binoculars - a good deal less so with a large reflector! For trips away from home binoculars are ideal and can be carried as hand luggage.
The choice of binoculars for astronomy is fairly straightforward. Binoculars are described in terms of magnification and aperture. For example 10x50 binoculars have a magnification of 10 times and the main lens (objective lens) has a diameter (aperture) of 50mm. Aperture determines the light gathering ability of any optical instrument. A larger aperture means more light captured.
With an aperture of 50mm, under ideal conditions, the faintest stars will be of magnitude +11.2 so a pair of 10x50's should be able to show you all 109 deep sky objects in the Messier Catalogue.
Keep it Steady
With a steady mount you are more likely to see fainter stars and deep sky objects, and resolve finer lunar detail than you would by the hand held route. By the time we get to the realm of larger binoculars like 15x80, weight considerations make tripod mounting essential.
Optics and Mechanics
Like telescopes, binoculars come in a variety of configurations, each of which uses prisms to fold the optical path into short tubes. The most common is Porro prisms in which the eyepieces will appear slightly offset behind the objective lens. Roof prism models have a more strait through layout. Focussing is often done via a central knob and good binoculars will allow independent focussing for either eyepiece - essential for everybody with less than 20/20 vision.
With binoculars (and everything else) you get what you pay for. Top end binoculars will have ED glass optics and high transmission coatings and some may even have image stabilisation built in, but these cost a pretty penny. You can also pick up a decent low magnification pair for less than £20 at the supermarket.
The Binocular Sky
More powerful binoculars (mine are 15x70) can resolve the larger moons of Jupiter and the rings on Saturn and the phases of Venus. You can't make out any surface detail or the ring divisions, but even so, it's still a great sight. Even the large asteroids Vesta, Ceres, Iris and Flora are visible in 10x50's with some patient observation.
Messier objects are good targets as well. M45 Pleiades is a prime target, as is the star cluster M24. M42 The great Orion nebula is a favourite of mine and does not disappoint on a dark night. Even galaxies are visible with binoculars. The Andromeda galaxy (another favourite of mine) puts on a good show during the autumn months and can be easier to see in binoculars than a telescope.