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 mounts to any Sony (or Minolta Maxxum) camera and works on both "full frame" cameras like the DSLR-A900 as well as the "APS-C" style digital SLR cameras, but the aperture is neither communicated to nor controlled by the camera body. As such, you can use the lens in "M" manual exposure mode or "A" aperture-priority mode only and in both cases you will physically move the aperture ring to the aperture of your choice and it will stay at that aperture even before the exposure.
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.