Category: Telescope Making

What you need to know when it comes to optimizing your scope’s thermal behavior.

Generations of backyard astronomers have debated why, inch-for-inch, the performance of a high quality refractor usually edges out an equal-quality Newtonian reflector. This disparity is most apparent when viewing low-contrast planetary detail — the images in a good refractors often have a touch more snap to them. Is there some intrinsic shortcoming in the design of the Newtonian reflector that makes this inevitable?
Continue reading “Beat the Heat: Conquering Newtonian Reflector Thermals — Part 1”

Solving the thermal management puzzle can be as simple as adding a fan to cool your telescope’s primary mirror.

In Part 1 I described the cause and consequences of telescope thermals, now let’s see what can be done to cure, or minimize the problem.
Continue reading “Beat the Heat: Conquering Newtonian Reflector Thermals — Part 2”

The secondary mirror holder and spider on my 12¾-inch truss-tube Dobsonian is made with scrap wood, a few nuts and bolts, and a stainless-steel ruler.

The curved-vane secondary mirror holders I use on almost all my telescopes never fails to excite curiosity. Most people know that the principal benefit of the curved spider is spike-free stars, but they often wonder if it really works. The “points” adorning bright stars in telescopes with straight-vaned spiders are diffraction artifacts that don’t seriously affect the image but do impose an aesthetic quality that may not appeal to you. Luckily, the remedy is easy to make, works like a charm, and can be retrofitted to virtually any reflector — commercial or homemade.
Continue reading “How To Build A Curved-Vane Secondary-Mirror Holder”

With star-party season upon us once again, you’re probably confronting the age-old problem of how to protect your prized telescope from the triple threat of dust, rain, and heat. The traditional big, ugly trash bag or blue tarp works for two of those three (dust and rain), but looks bad and lets your scope to get way too toasty on a hot summer’s day. Alternatively, you can plunk down $50 or so on a proper dust cover, but if you’re like me, that cash almost always seems to go towards another eyepiece instead. Stumped? Don’t worry — a cheap, effective telescope cover is only as far away as your local hardware/camping-supply store.
Continue reading “Save Your Scope!”

Remounting your Newtonian reflector’s primary mirror could lead to better performance and easier collimation.

Many telescopes have mirror mounts that are less than ideal. Some hold the mirror in place with clips that project over its surface and introduce image-harming diffraction effects. Others have adjustments that require tools or are so frustrating that observers rarely attempt to properly collimate the optics. Some cells effectively seal the mirror from the outside air. With no provision for ventilation, it is virtually impossible for the primary to cool down to the ambient air temperature — crucial for sharp images. Some mirror cells have all these problems!
Continue reading “A Simple Double-Plate Mirror Cell for Your Reflector”