Astro-Tech 1X Field Flattener For Astro-Tech AT80EDT Triplet APO Refractor

The AT80EDT is one of our most popular grab-and-go imaging refractors — 80mm of FK-61 triplet glass at 480mm f/6, compact enough for airline travel and light enough for small mounts, but sharp enough for serious deep-sky work. At f/6, the field curves. Stars in the center are tight. Stars toward the edges stretch. That's not a flaw in the scope — it's what any uncorrected refractor does to a flat sensor. A dedicated field flattener fixes it. The AT80EDTFF is a 1× flattener designed specifically for the AT80EDT. It doesn't reduce the focal length or change the focal ratio — you keep the full 480mm at f/6. What it does is flatten the field so stars are round and sharp across your sensor. The AT80EDT delivers the light. The flattener makes sure that light lands correctly on the chip. Sensor Coverage — What to Expect The AT80EDTFF delivers excellent correction across APS-C sensors (roughly 22×15mm) and smaller — round, tight stars from center to edge. On full-frame sensors (36×24mm), you may see some residual curvature at the extreme corners. This is an 80mm scope at f/6, and the corrected image circle has its limits. For most APS-C imaging — which is the sensor size most commonly…