Tuning up the Celestron Travelscope 50

In the good old days, refractors are used to be worry free instruments. Even for those without adjustable lens cells, the scopes would be correctly collimated out of factory. However, this is not the case any more, especially for the entry-level models. This is hardly anyone's fault because we are now paying one-third or even …

DIY Old School Guiding Eyepiece

In the old days when doing astrophotography without digital auto-guiding, most guide-scopes were long focal length refractors, usually no larger than 4". On top of that, one would also need a high-power eyepiece (about 9~12mm) with an illuminated reticle for continuous monitoring on guiding errors. However, such guiding eyepieces are often quite expensive, about 2~3 …

The Celestron Stock 20mm Eyepiece

My Celestron Astromaster 70AZ came with these two eyepieces. Many people would immediately ditch them for "better" ones but I would suggest to wait until they are fully utilized. Judging from the look of them, they should be same as the Super 20mm and 10mm from Skywatcher. The 20mm in particular is a great general …

The Celestron Stock 10mm Eyepiece

Many entry-level telescopes (Celestron, Orion, Skywatcher) include a set of eyepieces like the above, economical 3-element of unknown designs. Most people simply called them "modified achromatic", "modified Kellner", or just "Kellner". So what actually are they? A "true" Kellner consists of a singlet bi-convex field lens and an achromatic doublet plano-convex eye lens, it has …

The Celestron Travelscope 50 and Its Upgrades

I bought this Celestron Travelscope 50 used without the tripod, the 3x barlow, and its bag, for $20CAD several years ago. At that time, it was the cheapest way to get two 1.25" barrels for my DIY eyepiece projects. Since then, I have been doing numerous upgrades to the OTA in order to make it …

My Grandma’s Tecsun R-911

The Tecsun R-911 is a pocket-size AM/FM/SW receiver that was introduced in 2002. It is well know for its high sensitivity and exceptional selectivity. This particular unit was given to my grandma as a gift from her nephew in China. I believe it was initially designed for the domestic market because the controls, buttons, tuning …

bōrne PR1230SW

Last Christmas, I saw this radio being sold at one of the retail/drug-store chain in town for $30CAD. So I decided to give it a try. It is loaded with a lot of features, which radios at this price range often lack of. First of all, instead of a tuning knob, it has up/down tuning …

DIY 76.2mm f9.4 Refractor

About two years ago, I bought an used toy refractor telescope at a pretty good price with the intention of disassembling it for parts. Its objective lens is not the usual 50mm or 60mm, but a "big" 80mm! Further, it has an alt-azimuth mount with dual-axis slow-motions and a standard dovetail mount. The mount was …

Panasonic RF-569

The Panasonic RF-569 is a 1979 vintage AM/FM radio. I bought mine used from an online classified at merely $5CAD with the hope that I would be able to do some AM DXing - listening to distant AM stations. At night, AM radio signal travels much further than it does during the day because of …

Adapting a .965″ Orthoscopic to 1.25″

This Celestron Circle-V (i.e. made by Vixen) Orthoscopic 6mm was bought in the early 1990s. It is one of the two .965" eyepieces that I still have, the other being a Circle-V K40mm. Both of them I enjoyed using on my 60mm f/15 refractor (with a .965" focuser, of course) which I no longer have. …