>>3051407I have had several mirror lenses throughout the years, including this monstrous 1000mm Meade telescope that I picked up for $10 at a thrift store (seen here dwarfing my d800 and 35 1.8) They're not all they're cracked up to be, as they can fall out of collimation with time. And even if a mirror lens were perfectly collimated, it still wouldn't resolve as well as even a lousy refracting lens. That's just an inherent flaw to the design. So you can't just say that you can throw a 500mm mirror lens on a full frame camera, crop it down to 1/4 resolution and you'll get better performance than the p900. It just isn't true.
