Third-party accessories may not fit on a Celestron NexStar 5 even if they’re designed to do so. Apparently, some NexStar 5 telescopes are a little thicker around the corrector plate than others are, so even accessories specifically designed for them may not fit if the tolerances are too tight. I found this out in my recent shipment from Kendrick Astro Instruments, which arrived today. Their solar filters and Kwik Focus are designed to cover a telescope’s objective lens or corrector plate, and be tightened with screws. They’re sized to fit based on the telescope tube’s outside diameter (OD). My NexStar 5 SE has an OD of exactly 150 mm, which is on the cusp between two sizes. The smaller one was advertised to fit my telescope, so I ordered it. It doesn’t fit, and according to the Kendricks — who are, incidentally, wonderful to deal with — it should have fit easily. So back it goes, to be replaced by the larger model.