A reality based independent journal of observation & analysis, serving the Flathead Valley & Montana since 2006. © James Conner.
Some 20 years ago, I paid $50 for a Samyang 500mm f/8 catadioptric lens, probably a Maksutov design. Photographers sometimes call these reflex lenses, but catadioptric, meaning a combination of mirrors and refracting lenses, is a more precise term. Catadioptric lenses are popular with astronomers, but not with photographers due to fixed apertures, annular bokeh, low contrast, and modest resolution. They’re light and compact, but getting a sharp image handheld is a matter of luck, not skill.
Because I have a 470mm f/7.1 prime lens/teleconverter combination, my Samyang has stayed in its rich brown leather case. But on a whim this morning, I took it out and, handheld, shot a birdhouse approximately 100 feet away. Luck was with me. I wouldn’t call the image tack sharp, but it was sharp enough to resolve the “District 5” lettering.
This genre of lenses is still available at low cost for bargain brands. I still wouldn’t pay more than $50. If you have a good 200mm or 300mm prime lens, an aftermarket teleconverter such as Kenko’s 1.4X or 2X probably is a better investment (check eBay and camera stores for used equipment).
Above, the full frame reduced from 4,288 to 730 pixels in width, sharpened and processed for contrast and tonal range. Place your mouse’s cursor over the image to see the original.
Above, actual pixels. Low frequency (coarse) detail is resolved tolerably well, but high frequency (fine) detail is not. For some purposes this lens performance is quite acceptable.