The Bower 85mm f/1.4 Manual Focus Lens is a special effort in the independent lens manufacturer world, being a popular focal length for serious portraiture combined with an extra large f/1.4 maximum aperture. Most independent manufacturer lenses are either zooms or very short or long focal length fixed lenses.
This lens is appropriate for Pentax "full frame" film cameras in addition to their current 15 x 22mm "APS-C" style digital SLR cameras and presents no limitations to the camera operation beyond the manual focusing-it is for all practical purposes a "KA" style mount and communicates the lens' aperture to the camera body.
With a 35mm equivalent focal length of ~127mm and that f/1.4 aperture, this Bower 85mm lens opens up photographic opportunities you'll never get with your zoom. Capture close portraits of singers on dark stages with only spotlights on their faces and those background lights will be soft cascades of low-contrast coloring.
This lens was truly created with large-aperture shooting in mind. Though a fine performer with plenty of contrast and resolution at f/5.6-f/11 apertures, it is at its best shooting between f/1.4-2.8, where it presents a high-peak-resolution focus point surrounded by lower resolution/contrast out-of-focus areas.