'World's sharpest' 250mm lens now on Kickstarter with swappable lens mount

Taiwanese lens manufacturer William Optics is proposing to make a flatfield Petzval lens aimed at star gazers and photographers that it claims is the world's sharpest 250mm. Originally conceived as a compact and lightweight telescope for astrophotographers, the Redcat 250mm F4.9 uses a pair of synthetic fluorite elements to correct the usual field curvature of the Pretzval design to produce a sharp image right across the frame, according to the company. It is also claimed the lens is corrected t...