This lens features a compact, lightweight design that is about 70% in size and 50% in weight less than the 300mm F4 ED (IF) lens. This reduces the load on the photographer such as when walking of long distances is required to reach a shooting site. The lens features impressive delineation performance and uses extra-low dispersion (ED) glass for minimizing color blurring and providing sharp, high-resolution images with high contrast. Focusing can switch between AF/MF at the touch of a button, and an inner focus system is used to provide a speed AF option for providing superior ease of operation overall. A large hood with a PL filter operation window is also supplied.
This lens has a construction of 15 elements in 13 groups that is designed for high quality images. It even has extra-low dispersion glass elements that minimize the effects of chromatic aberrations and provide high contrast images for maximum resolution. This is all protected by a Super Protect (SP) coating on the front element that lessens the possibility of scratches and makes it easier to clean.
During operation, the lens internally focuses, keeping the large lens as compact as possible, and it switches from auto to manual focus by sliding the focus ring forward or backward. The lens also has a minimum focus distance of 6.6 and a filter thread size of 67mm.
35mm focal length equivalent of 118.5-237mm
Aperture range of f/5.6 to f/45
Angle of view of 21° to 10.5° which equates to 17° to 8.5° on Pentax 645 digital cameras
Lens construction of 15 elements in 13 groups
Two extra-low dispersion glass elements help to minimize chromatic aberrations and maximize sharpness
Accepts 67mm threaded filters
Minimum focusing distance throughout the zoom range is 6.6'
Super Protect coating on the front element helps keeps your lens scratch free and easy to clean
Internal focusing keeps the lens as compact as possible during use
Works with both film and digital formats
Aperture ring and focusing distance scale
Eight diaphragm blades for smooth out-of-focus areas