Astromania 1.25" 27mm Premium Flat Field Eyepiece - a flat image field and crystal-clear images Corrected field curvature for the best observing: Premium flat field eyepieces offer corrected field curvature, normally one of the flaws in optical imaging. This correction lets you use the entire field of view. You will observe an image with superior sharpness - not just in the centre, but right out to the outer edge. These eyepieces let you observe natural objects just as they appear in reality. Multi-coating and crystal-clear images: The large eye lenses will impress you at your very first glance at these eyepieces. The crystal-clear images you then see when looking through the eyepiece will then impress you even more. The high quality of the 5-6 lens elements and the high light transmission give you an image of high colour purity and excellent contrast. Twist-up eyecups: The eyepieces have solid and infinitely adjustable eyecups, making it easy for you to choose your most comfortable viewing distance - ideal for long intensive observing sessions. The various models have focal lengths of 8mm, 16mm and 19mm and are also ideal for spectacle wearers. Wide field of view - between 58 and 65: What does an extended astronomical object look like through the eyepiece, as compared to a standard Kellner or Ploessl? Imagine you are observing the Lagoon Nebula with an 8" f5 Newtonian telescope: While in the standard eyepieces the object extends well beyond the field of view, any of these wide angle eyepieces (around 19mm) will show you the entire object. This is because these eyepieces offer 20-30% larger fields of view than a standard eyepiece. Look great and last a lifetime with their anodized housings: These premium flat field eyepieces also look classy - the entire housing is anodized aluminium. This makes the material particularly resistant and durable. A rubber coating also provides you with a handy grip.