Ken Hough's Website
Where did I begin?|
Not having the benefit of timely advice, I jumped straight in and bought a large Newtonian telescope with a sturdy motor driven equatorial mount. Precisely what a newcomer should not do!
I was lucky!
My initial purchase turned out to suit me very well, but not before gaining a lot of practical experience.
Since making that first purchase, I have expanded my 'collection' of equipment so as to be able to accommodate various situations. This section is intended to describe my equipment and how I see the pros and cons of it.
Remember that no single telescope system can properly suite all situations.
Skywatcher Explorer 250PX Newtonian telescope with EQ6 PRO SynScan mount :
This 250mm/10" Newtonian telescope has a focal length of 1200mm. At F4.7, it is classified as a 'fast' telescope, well suited to viewing and photographing reasonably wide subjects such as nebulae. A 2" rack and pinion focuser was provided which worked quite well and included a T2 thread for mounting a camera body directly onto the focuser. This focuser was adequate for viewing via an eyepiece, but as with all 'fast' telescopes and photographic lenses, focusing was very critical, particularly when using a camera. I therefore changed the original focuser for a Moonlite dual speed Crayford focuser. Moonlite focusers are not cheap, but are of very high quality, are a pleasure to use, and can support heavy cameras, etc.
Recent versions of this telescope are supplied with dual speed Crayford focusers.
All Newtonian telescopes suffer from 'coma' which causes stars at the edge of the field of view to appear smeared outwards instead of being seen as points of light. Fast Newtonian telescopes can show quite marked coma. This is not usually a serious problem for direct viewing by eye, but can be very noticeable in photographic images. The solution is to use coma corrector element in front of the camera, or indeed in front of the eyepiece. I use the Baader Multi Purpose Coma Corrector (MPCC) which reduces coma to negligeable levels.
All Newtonian telescopes must be properly collimated if they are to perform at their best. This telescope is no exception, but I have found it to hold collimation well even during transport in a car.
The EQ6 SynScan is a motor driven equatorial mount that is capable of carrying a 300mm telescope! A computerised hand set is used to control the mount which includes Goto operation. An autoguiding port is included on the mount itself.
This is a substantial mount! The head of this mount on it's own weighs around 16kg! Add to this the weights of the telescope (12kg), counter balance weights(3 x 5kg), tripod (7kg), gives a total weight of around 50kg!
The EQ6 is well known as being one of the best 'budget priced' mounts for astrophotography. Once set up, it provides a steady platform which tracks well and is a pleasure to use! However, only the young, fit and strong would rate it as a truly portable system. I eventually replaced the tripod with a steel pier that is permanently sited in my back garden. The whole assembly is now protected by a weatherproof run-off shed. See below for details.
William Optics Megrez 72 semi APO telescope :
My next serious purchase was the little William Optics Megrez 72 telescope. This telescope uses 'ED' glass to provide near achromatic performance from a relatively cheap f=430mm doublet objective lens. I got this telescope to compliment the big Newtonian for wider sky imaging. It is an easy matter to swap the two telescopes on the EQ6 mount.
In my experience, this is a very nice little telescope both optically and mechanically. The two speed Crayford focuser is smooth and supports cameras well. Highly recomended!
With the addition of an errecting prism this telescope can also serve as a very good if slightly heavy spotting scope. Most often, the Megrez 72 is now mounted alongside my Newtonian telescope, to be used either for 'wide sky' observation and photography, or to operate as an autoguiding telescope. See below.
Bresser 70mm achromatic refractor telescope and EQ3-2 mount :
This telescope was bought as a 2nd hand item via Ebay. The price was good so I couldn't resist! When I received the telescope, I was very disappointed with it's optical performance. Eventually, I discovered that someone had reversed one of the two elements that made up the doublet objective lens. After correcting this, performance was surprisingly good, and certainly good enough for eyepiece viewing at quite high magnification. Being an F10 telescope (focal length = 700mm), chromatic aberration was acceptably low. Again, with the aid of an erecting prism, it could be used as a spotting scope!
The EQ3-2, also bought 2nd hand, is a manually driven equatorial mount. This is quite light in weight and with the Bresser 70mm telescope makes a very easily portable viewing platform. I often use this setup (with the addition of a solar filter) to see if any sunspots are visible before opening up my main system.
Skywatcher Skymax 127 with EQ3-2 motorised mount :
I bought this system to regain the portability that I lost after fixing my EQ6 mount onto a static pier. This system is also significantly lighter than the EQ6 system, which makes it much easier on my aging back. The EQ3-2 provides a fair measure of stability which with the motor drive allows me to do some astrophotography.
The 127mm f=1500mm Maksutov Cassigrain telescope is a gem both optically and mechanically! Although not up to the light gathering power of my big Newtonian telescope, it is still of sufficient aperture to keep exposure periods reasonably short for many subjects. Like the more common Schmidt Cassegrain telescopes (SCTs), this little Mak' has considerable flexibility in it's focusing range.
Mak' telescopes are claimed to have lower optical aberations than Schmidt Cassigrain telescopes.
The main limitation of Maks lies in the use of rather thick front corrector elements. This means that Maks are relatively heavy and take longer periods to cool to ambient conditions when compared with SCTs. This isn't too much of a problem for a small 127mm telescope, but larger Maks can be problematical.
This little rig did not include a polar alignment telescope, but I intend to fit one.
Ancillary Equipment :
Many kinds of items can be considered under this heading including eyepieces, adaptors, extension tubes, 45/90 degree diagonals, alignment telescopes and similar devices, etc. The list could go on...
Each telescope is likely to be provided with it's own finder telescope. I now have quite a collection of these. However, I prefer to use either a 'red dot finder' or better still a 'Telrad' finder as these devices allow a more open and non reversed view of the sky. I find these non magnified views to be perfectly adequate to align my medium focus telescopes onto the intended targets. Users of long focus telescopes such as big SCTs might prefer to use conventional finder telescopes.
My main interest lies in astrophotography, so I also have to manage cameras and the associated array of adaptors, filters, cables and computer.
Storage of Ancillary Equipment :
I've described my main equipment above, but to use this and to maintain it in working order, a few extras are needed. For example, various screw drivers, spanners, Allen keys will be needed to collimate telescopes and to make other adjustments to the mounts. There will always be something that has to be tightened or adjusted.
Add to this a collection of eyepieces, adaptors, diagonals, alignment telescopes, etc and there can be a lot to manage.
My solution is to store these things in a lockable heavy duty plastic tool chest. This is waterproof when closed and can be used as a portable step when trying to look into the eyepiece of my big Newtonian telescope when it's pointed towards the zenith.