© Reeth Informal Astronomy Group unless otherwise indicated
Reeth Informal
Astronomy Group
covering the Northern Yorkshire Dales
The Mount
There are several mount designs but the two general types are the EQ or Equatorial Mount and the AZ or Alt-Azimuth mount. Now most, if not all, of the starter scopes which are below the £100 bracket are the manual AZ type, and with the exception of the Dobsonian version discussed below, these mounts are worthless in my opinion. They will cause you pain and frustration and you will most likely want to quit the hobby altogether because of them. The way the AZ mount works is that it moves the telescope on two planes at right angles to each other - up and down and left and right. Once you have managed to identify an object and brought it into focus you look into the eye piece and the object has moved out of view. Because of the way the mount moves you have to control both the side to side and the up and down at the same time to get the object back in the centre of the field of view, and on these cheap AZ mount this will always cause shaking.
To be honest the entry level EQ-1 mounts while very lightweight can be a much, much better option. This because the EQ mount moves on the two celestial planes - declination (from the celestial equator up to the celestial pole) and right ascension (parallel with the celestial equator) - which allows the mount to compensate for the rotation of the earth. (This is what causes the object to move out of the view with the AZ mount). So even with the manual EQ mount you will only need a gentle hand on one control knob to keep the object in the centre of the field of view - which is a lot easier and less frustrating!
The Actual Telescope!
Now we have talked about the two basic mounts we can now look at the optics, there are really three low cost types of telescopes in the starter bracket, the Refractor, the Newtonian and the small Maksutov-Cassegrain. For a starter or general observation then I can only recommend the Newtonian type. This is because it will give you the most out of your pound in terms of views and utility. The other two have their uses and pros and cons – but even though the Newtonian has its cons as well, we are on a budget and I cannot stress how much enjoyment this type of scope will give in terms of astronomy for the least amount of money.
This is because with the Newtonian Reflector you can get the largest aperture – which is the diameter of the main lens or mirror - for the least amount of money. A large aperture means the more light you can collect and the better you will be able to see objects. But there is an issue when thinking bigger is better. There is weight to consider, also setting up (getting optics to acclimatize to outside temperatures) but what you may not have considered is the atmosphere. With the really large aperture telescopes – over 8 inches - I have found that the air movements in the atmosphere can really put a damper on the viewing experience and enjoyment of the hobby.