AstroMedia Copernican Orrery kit – part 2

In part 1 I described the first half (approximately) of the construction of a cardboard Orrery kit from AstroMedia. In the second half things get more interesting, and more complicated, as the majority of the pulleys and shafts are assembled. The first part to be constructed is the “planetary gearing”. This will eventually roll around … Read more

Correcting vignetting in digital photographs — introduction

I recently purchased a budget telephoto lens for my Canon EOS 100D DSLR camera. It’s a 500mm f/6.3 mirror lens, essentially a small Cassegrain telescope. Like many budget lenses it suffers from “vignetting”, i.e. the edges of a photograph are darker than the centre. The EOS 100D camera has built in vignette correction (called peripheral … Read more

Some telescope accessories

Introduction After I bought a Borg helical focuser to use with my 4″ Mak I noticed that my other Sky-Watcher ‘scopes also have T-threads (M42x0.75) and/or “small Vixen” threads (M36.4×1.0) on their eyepiece holders. More recently I bought a Baader Maxbright mirror diagonal, which also uses these thread sizes, and some eyepiece holders with brass … Read more

Jim’s astronomy web pages

I have always had some interest in astronomy. My school prize in 1970 (at the age of 11) was “The Observer’s Book of Astronomy” by Patrick Moore, which I still have. While some parts are a little dated (it warns that you may have to spend as much as £50 to buy a 3 inch … Read more

Happy birthday, NASA

According to today’s edition of the always interesting Astronomy Picture of the Day, today marks the 50th anniversary of the creation of NASA. I hope the next 50 years are as exciting as the first.

Sky-Watcher SkyLiner 200 Dobsonian Telescope

Introduction I bought my 8″ Dob in June 2003 from Teleskop Service, a German online dealer. It’s a good value for money telescope, but as you might expect, it can be improved. This page describes some of the improvements I’ve made. After a year or so of having to “nudge” the scope to track objects … Read more

The Moon and Mercury

Last night I took my first astro photos for a long time. There was a near conjunction of the Moon and the planet Mercury. I set up my Canon 350d and Sigma 70-300 zoom lens in my bedroom, pointing out through an unopenable (and dirty!) window towards a cluttered horizon. By about half past eight … Read more

Eyepiece measurements

I’ve tried quite a few eyepieces since I bought my first real telescope, always in the hope of wide fields, bright images, a wide range of magnifications and little cost. I sell on those which I no longer have a use for, so I don’t currently own all the EPs listed below. I measure focal … Read more