Compact Pentax K mount 100mm f/4 telephoto with SMC coating and lightweight design.
The Pentax SMC 100mm f/4 is a compact telephoto prime for Pentax K mount, offering a moderate telephoto perspective with a compact form factor. The f/4 aperture keeps the lens small and lightweight while providing adequate speed for outdoor portrait and telephoto photography in good lighting conditions.
Optical quality is good with the SMC coating delivering sharp, contrasty images with the colour accuracy Pentax optics are known for. The simple optical formula produces clean images at working apertures. At f/5.6 to f/8, sharpness across the frame is excellent for a lens of this class and era.
Build quality is typical Pentax K mount manual-focus quality with an all-metal barrel, smooth helicoid focusing, and positive aperture click stops. The lens is remarkably compact and lightweight for a 100mm telephoto, making it an excellent travel companion for photographers wanting moderate telephoto reach.
On the used market, the Pentax 100mm f/4 is extremely affordable and provides a pleasant short telephoto experience. For Pentax K mount users wanting a compact portrait-length lens or adapted mirrorless shooters exploring affordable vintage glass, it delivers solid results at negligible cost.