11/2/2023 0 Comments Meade telescope reviewsPrecisely collimating a typical mass-produced Bird-Jones telescope like the Polaris 127 involves disassembling the focuser with a screwdriver, carefully unscrewing a plastic retaining ring to extract the corrector, collimating as with a standard Newtonian, and then meticulously re-inserting the corrector without contaminating it with focuser grease or fingerprints. The corrector lens itself is also extremely low-quality and does not allow the Polaris 127 to achieve sharp images even with other constraining factors absent anyway. Moreover, in the Polaris 127’s attempt to use the Bird-Jones configuration, the corrector lens is situated within the telescope’s plastic 1.25″ rack-and-pinion focuser, which creates issues with collimating the scope accurately and also means that the spacing of the corrector from other optical components changes when you adjust focus. The Bird-Jones design was never much of a hit among amateur astronomers, and in any case, it is now antiquated and no longer necessary, thanks to improvements in eyepiece design and optical manufacturing. The key component is the corrector lens, which in the original Bird-Jones design is supposed to be placed just before the light from the primary mirror hits the secondary mirror, fixing the spherical aberration that would otherwise be caused by the primary mirror. At the time the Bird-Jones design was conceived, eyepieces were basic and coma correctors were non-existent, so long focal ratios were essential for telescopes to provide sharp images, and this design allows for the use of a simple-to-make spherical primary mirror as well as keeping the tube fairly stubby and compact. ![]() Instead of the Bird-Jones optical design, it employs the same optics as the Celestron PowerSeeker 127EQ and numerous other telescopes with the same compromised specifications. The mystery unfolds when you learn that the Polaris 127 isn’t truly a Newtonian. However, this claim should immediately raise eyebrows, as the optical tube of the telescope appears to be far too compact to accommodate such a focal length. ![]() The Meade Polaris 127 claims to be a 127 mm (5″) f/7.9 Newtonian reflector, sporting a focal length of 1,000 mm.
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