Celestron Omni 9mm

The Celestron Omni 9mm is a straightforward, well-made Plossl eyepiece designed to deliver sharp planetary and lunar views without asking much of your wallet. At 9mm focal length, it produces meaningful magnification in most telescopes, making it a practical choice for splitting double stars, studying lunar craters, or pulling detail from the planets. The 50-degree apparent field of view is narrower than modern wide-angle designs, so do not expect sweeping vistas of star clusters, but for tightly focused high-magnification work it gets the job done.

The four-element Plossl optical design is a proven formula, and Celestron executes it competently here. Fully multi-coated optics help transmit light efficiently, and blackened lens edges reduce scattered light that can wash out contrast. The aluminum barrel feels solid for the price, and the threaded barrel accepts standard 1.25-inch filters, which is genuinely useful for lunar and planetary observers.

Eye relief at this focal length is short, roughly 5 to 6mm, which is typical for Plossls in this range. Eyeglass wearers may find the rubber eyecups less helpful than they would with a longer eye relief design. At under $30, it represents honest value for someone building a starter eyepiece kit.