Zoom

20-40mm F2.8 (Zoom lens, equivalent to 40-80mm for 35mm camera)

“This is actually three lenses in one - wide-angle, standard and moderate telephoto. It gives you a great deal of flexibility in framing and is extremely easy to use with a single ring for zooming and focus. Fine for sports, portraits or all-round photography, this handy, high-quality zoom fits right in your pocket.” Pentax literature, June 1984

zoom_03
zoomhood_oncamera

Shown above is the VERY rare lens hood for the zoom lens!

The zoom lens was a superb, if quirky, design with an opposite push-pull to normal zoom lenses and an advanced lens element design. It did not have a particularly wide range, 20 - 40mm is the same as a 40 - 80mm range on a 35mm camera. The zoom and the 70mm had metal casing instead of the plastic casings on the rest of the lens range.
But, this metallic design added weight and proved to be a bit too much for the small bayonet. The flanges on the lens are weaker than the camera mount and if not properly fitted the result was bent flanges and in some cases the flanges broke off completely.