This guide is intended for those using a telescope for the first time, the tips are based on common problems that get encountered by those new to astronomy. We are more than happy to meet you and your telescope and help solve your problems so feel free to contact us. You don’t even have to join but we would love it if you did.
I can’t find anything!
Aligning the finder
Telescopes usually come with a finder of some sort, this will either be a small telescope mounted to the main instrument, a ‘red dot’ finder or some method of sighting along the telescope tube. The purpose of the finder is to help you point the telescope in the direction of the object you are interested in, and thus it is important that the centre of the field of the finder and the main telescope are pointing to the same area of sky.
The easiest way to align the finder is to focus the main instrument on to a distant object such as a street lamp or roof top aerial, this is best done in daylight so you can see what you are doing, make sure you have the drives off, if you have them, and 25mm or larger eyepiece. DONT POINT THE TELESCOPE NEAR THE SUN
Once you have a reference in the centre of the field of the main telescope lock the mount so that it doesn’t move and adjust the finder until this is pointing at the same object, once you have done this move to a different object and confirm both are still pointing to the same thing. You can refine this by using smaller and smaller eyepieces in the main telescope which will magnify the view. Practice moving the telescope to new stationary objects and seeing how good you can get at getting the object in the centre of the eyepiece – this will all help when it is dark.
Field of view
Telescopes can have a small field of view, so to find an object follow these simple rules.
- Find the object first in your finder (see above for aligning it), this should have the largest field of view. Centre the object in the finder.
- Using your largest eyepiece in the telescope*, this will be the eyepiece with the largest focal length, or if your eyepieces are marked with their magnification it will be the smallest magnification, center the object in the telescope.
* this eyepiece will have the widest field of view so you will have the biggest chance of seeing it if your finder and telescope are aligned.
- To get a more magnified view (and usually also a smaller field of view) move through your range of eyepieces, starting with the largest focal length and working down, re-centre the object each time.
Telescope not tracking?
If you are using your telescope visually (i.e. you don’t have a camera attached) and it has a clock drive it should keep your chosen object in the eyepiece for some time. If not, then you have probably set the telescope mount up incorrectly. For this article we will assume you are using a simple German Equatorial Mount (GEM)
The GEM has two axis (see Choosing a telescope) that move the telescope in RA and DEC. The RA axis (consult your manual) needs to point North, for visual use this doesn’t have to be that good an alignment, indeed during daylight observation of the Sun (solar safety) I simply guess where North is and this rough alignment is good enough for visual use and for use when ‘web camming’, the other consideration is the angle of this axis, this needs to be roughly set to your latitude and anywhere in the south east of England setting it to 52 degrees will be fine.
Lock the axis
Once polar aligned, to drive the scope you need to turn on your drive and lock the RA axis (there is usually a clutch to do this)
if this still doesn’t work…
- Check the power to your scope drive
- Check the drive is set for northern latitudes (there is usually a button or setting for this)
- If you have access to the gears touch the RA gear and feel if the motor is turning it, if not you have an electrical/electronics problem, if it is check the gears are not slipping.
GOTO doesn’t work
Ok so your GOTO doesn’t behave as it was advertised, let’s look at what might be going wrong…
Most GOTO systems require some level of set-up, first check your manual, especially check the polar alignment (see tracking above).
- Check the starting position of the scope, many goto systems require the scope to be set to a specific ‘home’ position when first turned on – often pointing North but not always
- Check the clutch’s are not slipping
- Check you are pointing at the correct star (then check again!), make sure this star isn’t just in the field but in the centre of the field, if you don’t have a reticule eyepiece use your highest magnification, which will have the smallest field to ensure the star is as central as possible before clicking ‘align’
- Check your scope is level (most have a small bubble level for this purpose
If you are still having problems especially if your scope point in radically in the wrong part of the sky (or ground!) then check points 2 and point 4 again.
Often it is best if you bring your scope along to us on a Thursday night, and we can walk you through using it, if you do come along please contact us to let us know.