Professional Pentax 645 super-telephoto with ED glass and AF, unique medium format reach at 237mm equivalent.
The Pentax SMC FA 645 300mm f/4 ED IF is a professional super-telephoto prime for the Pentax 645 medium format system, providing a perspective equivalent to approximately 237mm on 35mm format. The FA designation indicates autofocus capability, and the ED glass controls chromatic aberration at this demanding focal length.
The 300mm focal length on the 645 format provides genuine super-telephoto reach for wildlife, sports, and nature photography with the resolution advantage of the larger medium format sensor. The f/4 aperture is relatively fast for a medium format super-telephoto, and the internal focusing design maintains constant barrel length.
Build quality is professional-grade with robust metal construction designed for demanding field use. The ED (Extra-low Dispersion) glass element reduces colour fringing that becomes visible at long focal lengths, and the SMC coating ensures clean contrast. A tripod collar provides stable mounting for precise telephoto work.
The FA 645 300mm f/4 ED is a rare and specialised lens commanding strong prices on the used market. For Pentax 645D/Z users who need genuine super-telephoto reach with medium format resolution, it provides a unique capability that no other current medium format system can match.