Essential Astronomy Accessories 2026

The Moon through a telescope is bright. Painfully, squint-inducingly bright — especially through a 6" or 8" scope near full Moon. An ND 0.9 filter cuts the light by about 87%, bringing the glare down to a comfortable level and actually revealing more surface detail because your eye isn't being overwhelmed.

It screws onto the barrel of any standard 1.25" eyepiece. Put it on, point at the Moon, and suddenly you can see craters, mountain ranges, and rilles without feeling like you're staring at a car headlight. At £11, this is the most cost-effective accessory in astronomy — and almost certainly the first one you'll wish you'd bought sooner.

The Telrad is the single most popular finder upgrade in amateur astronomy, and it's been in production largely unchanged since the 1970s — because it works. It projects three concentric red circles (0.5°, 2°, and 4° diameter) onto a tilted glass screen. You look through it with both eyes open and see the circles overlaid on the real sky, making it trivially easy to point your telescope at the right patch of sky.

Most beginner telescopes come with a small optical finderscope or a basic red-dot finder. The Telrad is better than both because the circles give you a sense of scale — the 4° circle is roughly the width of your fist at arm's length, and many star atlases are designed with Telrad circles in mind. Star-hopping from a known star to a faint target becomes a matter of "move two Telrad circles east and one north."

It attaches to the telescope tube with an adhesive base (included) and runs on two AA batteries that last months. The brightness is adjustable — use the dimmest setting that's visible to preserve your night vision.

If you own a Newtonian reflector (Heritage 130P, Heritage 150P, Skyliner 200P, or similar), your mirrors need to be aligned — collimated — for the telescope to produce sharp images. Transport, temperature changes, and the odd bump can knock them slightly out of alignment. A miscollimated scope shows bloated, asymmetric stars and soft planetary detail.

The Rigel Aline is the simplest collimation tool: a plastic cap with a precisely centred peephole and crosshairs. You slot it into the focuser, look through the hole, and check whether the reflections of your primary mirror, secondary mirror, and the crosshairs are all concentric. If they're not, you adjust the mirror screws until they are. The whole process takes 2–3 minutes once you've done it a few times.

At £6, there is no reason not to own one. First Light Optics themselves say "every Newtonian owner should have one."

The fixed ND 0.9 Moon filter (#1 on this list) is perfectly good for most lunar observing. But a variable polarising filter gives you continuous control — rotate the two polarising layers against each other and you can dial the transmission from roughly 1% to 40%. This means you can match the filter to the Moon's phase: a thin crescent needs barely any filtering, while a near-full Moon wants heavy attenuation.

It also works on bright planets. Venus, in particular, benefits from some attenuation — it's so bright it can overwhelm detail in a telescope. Jupiter at opposition can also be slightly too bright in larger scopes.

The Astro Essentials version fits 1.25" eyepieces and has a knurled ring for easy adjustment in the dark. It's £13 more than the fixed filter but considerably more flexible.

The UK's maritime climate means one thing for telescope owners: dew. On a typical clear night, moisture from the air condenses on any exposed optical surface — your corrector plate, secondary mirror, or finderscope — within 30 to 90 minutes. Once it fogs up, your session is over unless you have a way to prevent or remove it.

A dew shield is the simplest prevention method: a flexible fabric tube that extends the front of your telescope, slowing radiative heat loss from the optics and delaying the onset of dew by an hour or more. It doesn't use power, doesn't add significant weight, and folds flat for storage.

This 8" version fits Skyliner 200P tubes and similar 8" Newtonians. Smaller and larger sizes are available for other scopes. For Schmidt-Cassegrain and Maksutov telescopes (where the corrector plate is the most vulnerable surface), a dew shield is not optional — it's essential from night one.