Pentax's ED long tele — the SMC Pentax 67 300mm f/4 ED IF, low-dispersion glass for 6x7.
The SMC Pentax 67 300mm f/4 ED IF is a long telephoto lens for the Pentax 6x7 medium-format system, from the late SMC Pentax 67 generation of the line. Introduced in 1999, it modernised the system's 300mm with extra-low-dispersion glass and internal focusing, following the earlier Super-Takumar 6x7 300mm on the 6x7 negative.
This is a manual-focus lens for the Pentax 67 bayonet mount, covering the 6x7 cm frame. It has a fixed 300mm focal length and a maximum aperture of f/4. The ED suffix marks extra-low-dispersion glass to curb chromatic aberration, and IF denotes internal focusing so the barrel does not extend; the Super Multi Coating controls flare on the long field.
The ED glass reduces colour fringing at the long focal length, which matters for the fine detail the 6x7 negative records on distant subjects. The internal focusing keeps the lens balanced and speeds focus travel, and the 300mm reach suits landscapes and wildlife where perspective compression and subject isolation are wanted.
On the used market this late ED telephoto is one of the more advanced and pricier long lenses of the line, valued for its correction. Check the elements for haze and cleaning marks, confirm the internal focus runs smoothly, and look for fungus. It adapts to mirrorless through a Pentax 67 mount adapter for the reach on digital bodies.