Originally posted by Samsungian Mirrors are not a replacement for real variable aperture supertelephoto glass.
The fixed aperture ones aren't. I don't see any reason why variable aperture ones wouldn't be for very long telephoto applications.
The difficulty with the existing solution is at least as much cost as weight; it's very, very expensive to make refractor telescopes with an objective lens larger than 100mm and no one seems willing to try above 150mm or so.
Maybe better lens technology will solve this. But that doesn't seem as likely as "maybe a refractor design isn't the best way to do this".
Originally posted by Samsungian I've owned 4 mirror lenses, still own two, what I considered the best of the 4. You got to love the doughnut bokeh circles on anything shiny in background as thats what you get with them.
Hmmmm Doughnuts!!!
Bokeh is, to me, not a concern if the objective is to get a recognizable clear picture of a sparrow. It's record-keeping, with not much hope of art, and the picture will get cropped to the minimum bounding box that holds the whole sparrow.