The mirrors align…

Ever since the first mirrored telescopes came into being by non-other than Sir Isaac Newton (yes, that's why they are called Newtonians!), one thing has been constant, keeping the mirrors aligned. We're not talking pseudoscience here with planets and stars aligning to improve your life. Instead we're concerned with the optical path those precious photons take as they enter your telescope and get bounced back up to the secondary before entering your eyepiece. Newtonians are especially prone to the mirrors becoming misaligned but are relatively easy to collimate once you get the knack. For the archetypical Newtonian telescopes there are a variety of useful aids to achieve optical alignment, also known as collimation, and these range from a basic Cheshire eyepiece to advanced laser collimators.

However Catadioptric, also known as compound telescopes, have a combination of front corrector plate that also usually holds the secondary mirror, as well as the primary mirror at the back of the telescope. This makes them very compact and as a rule also quite robust and less likely to have their optics become misaligned. However it does happen and aligning a compound telescope can appear quite daunting. In the latest issue of BBC Sky at Night Magazine I take a look at the HoTech advanced CT laser collimator and took a chance by deliberately misaligning the optics of a borrowed 8-inch SCT before using the collimator to correct the error. Check out how I got on and whether the telescope was still useable after I concluded the review.

In the meantime, fancy taking high-resolution video of the Solar System? Regular BBC cameraman Mark Payne-Gill tested out the Orion StarShoot HD video/web broadcasting cameras for us. Meanwhile Steve Richards put the Avalon M-Zero mount through its paces - what a smart looking piece of kit it is too! Check out the above and more in our November issue, out now.


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