500mm · f/6.3
The 3M-6A 500mm f/6.3 mirror lens delivers surprisingly good handheld results, though a tripod is recommended for optimal sharpness. It is well-constructed with smooth focus and no backlash, but lacks a lens hood and has a fixed aperture. Optical strengths include good sharpness when focused, but shallow depth of field and difficulty focusing handheld are weaknesses. It suits budget-conscious photographers needing a long telephoto for stationary subjects.