At this time of year especially DEWING - the formation of condensation – is a headache for astro-imagers and telescope users. If you have a power-supply, plug your old hair-dryer in and gently waft some warm air onto the front lenses of your telescope, finder, or camera lens. Carry your eyepieces in a warm (lint-free!) pocket, and use DEW-CAPS on all front lenses. You can make a dew-cap very easily from rolled cardboard painted black & a rubber band. Not pretty, but it works!
Looking slightly to the side of a faint object, instead of directly at it, gives a much improved view, because the retina is most light-sensitive around the edges. It is also important to move the eyes around a little while observing, because an image kept at the same point on the retina is ignored by the brain after a time.
At night when taking astrophotographs it is very difficult to frame the star field in the view finder. To overcome this you can make a ‘star frame’ from a wire coat hanger by forming it into a rectangle 20.5cm by 25.5cm, keeping the handle at the bottom left hand corner. Held at arms length the area of sky covered will be equivalent to the field covered by a 35mm SLR camera with a 50mm or 55mm lens. Note the position of a bright star in the frame and then use the same position for the star in the view finder. The frame can be adjusted in size for longer – or shorter – lenses if needed.
If you do not have a Moon filter for your telescope try viewing a near Full to Full Moon wearing a pair of sunglasses to reduce the glare. Another trick is to place a bright white light behind you (about a 60 watt light) when you observe a Quarter to Full Moon.
The addition of a white light suppresses the eyes’ tendency to dark adapt at night. Not dark adapting causes the eye to use normal daytime vision, which is of much higher quality than dark-adapted night vision, allowing you to see more detail.
Eye relief of at least one centimetre, that is the distance from the eye piece that an object can be seen clearly, is important especially if you wear glasses.
However, remember that by using a shorter focal length eye piece, i.e. increasing the magnification, one reduces the amount of eye relief.
As a quick guide to judging distances between celestial objects use your hand at arm’s length.
One finger is roughly 1 °, a fist knuckle to knuckle is 10 °, and a spread hand’s width is 20 °.
As a beginner astronomer don’t immediately buy a very expensive telescope. After you become familiar with the major stars and constellations and want to move up from naked-eye astronomy look for good binoculars (preferable the 7 x 50 or 10 x 50 size). An essential tool for any serious amateur astronomer, binoculars bridges the gap between naked-eye and telescope.
When you feel ready for a telescope, purchase something simple and easy to handle. My preference is for a 6 or 8 inch (150mm or 200mm) Dobsonian mounted reflector, which is relatively inexpensive and user friendly and will reveal hundreds of cosmic wonders. After a few years, if you still have the astronomy bug, then upgrade to a larger more expensive telescope.
Also read: Binocular Astronomy by John Richards and Buying a Telescope - Important Things to Keep in Mind by Lee Labuschagne.
The magnitude of objects as they appear on the sky is known as the apparent magnitude. This scale is logarithmic and ranges from -26, very bright, to +30, very dim. Thus a difference of 1 magnitude corresponds to a factor of 2.5 in brightness and a difference of 5 corresponds to 100 in brightness (2.55 = 100). A star of magnitude 6 is considered the limiting brightness for the naked eye under dark skies. E.g. Sirius the brightest star is -1.4 and Vega is 0 on the magnitude scale.
With thanks to Tony Jones