Telescopes

Telescopes

The telescopes I use in my observatory.

Pete's Pages

Drift Method of Polar Alignment
For more information on collimation try
http://perso.club-internet.fr/legault/collim.html

My Telescopes

Meade LX-200 8 inch I originally brought the LX-200 with automation in mind. It’s go-to facility seemed ideal for the price of the scope, although prices in England are twice that in America. I wish now I had explored the possibility of getting it thought the web, as I’m sure Telescope

now it would have been cheaper. I went for the 8 inch at the time because of the price difference between the 8, 10 and 12 inch. Sometimes I wish I had saved up for the 10 inch but that’s history now. I mounted it on the standard Meade wedge but found this a little unstable so I bolted several plates to the side of it to strengthen it. It’s still not perfect but it’s a lot better than it was. The wedge is placed on a homemade plate with holes in it to put eyepieces and to hang the control box for the LX-200. I have had just one problem with the scope in the three years I have owned it. Every now and then the declination. motors start in ever direction at the slew speed it happens to be on. I have not cured this problem but I have learned to get around it. It seems that certain keys pressed in the right order start it off. Luckily it only happens when I use the keypad and not when I control it from my computers so I am always there to stop it if it decides to do it’s own thing. The Go-TO facility is very good. It always put the object in the 25mm eyepiece even from one side of the sky to the other. When CCD ing I need to align on a star every 20 degrees or so to keep it on the chip. This is because of the small field of view. The scope does suffer quite badly from dew. I cured this problem with a dew shield made from the foam sleeping mats. They are cheap and very light are very effective. Even on a heavy dew night they work all night with out any problems. The optics seem very good although I have little to compare them with. I have culminated the scope twice now, as it just needed tweaking a little. It needs no more than that, probably because it is never moved, knocked or has any harsh treatment. When I compare planetary views with my ETX the ETX seems to give a slightly sharper image although the LX-200 shows more surface detail. Towards the edge of the field, the LX-200 seems to blur a little, especially with a wide field view.

I have recently upgraded to LX-200 GPS see review

Meade ETX 90 Generally a great little scope. The optics are good and its very easy to use. I have the old version without the go-to facility. The focus knob is a bit fiddly so one day I intend to put on a bigger one. Forget about the finder scope as it’s not of good quality and it’s very difficult to see though because it’s a straight through type. I understand the new version with the go-to facility has a 90-degree finder scope on it. I use it mounted on my LX-200 so I’ve taken it off its mount and removed the finder scope. I made up two mounts for it and these run on the rails I made for my 2D balancing weights. I have only used it 3 or 4 times on it’s own mount. I installed it on the LX-200 tripod with a special wedge I made up so it is quite steady. To save time and money the wedge cannot be adjusted for declination. This is not as bad as it seems as when I do use it; it’s always at the same location. For any small adjustments I put cardboard under the tripod legs. Once aligned it tracks quite well for visual observing although you have to be quite a contortionist sometimes to use the viewfinder. On the back of the ETX there is a peculiar arrangement for attaching a camera witch works quite well. The ETX has a built in diagonal with a flip mirror in it. Just give another fiddly little knob a quarter turn and the view is straight through onto the camera. Turn it back and it’s in the field of view again. When not on the LX-200 I use it mostly to take pictures of the Sun, as solar filters are quite reasonable for such a small scope. Fro visual observing it’s also god for planets and takes a Barlow with no problems because it only has a push pull eyepiece holder. I cannot use my focal reducer easily with it and this could be a problem for some as it’s focal ratio is f13. (The screw thread for the camera is a different thread use mostly in photography. To mount a CCD or focal reducer on this thread I use a Celestron and a Meade adapter together which gives a thread like the one on the back of the LX-200.)