I think such a thing doesn't exist, but I may as well ask. I've seen auto zoom flashes that go from around 28mm to 85mm, sometimes to 105mm. And there's a Fresnel lens, the Better Beamer, to extend flash range, but should be used with 300mm lenses or longer or the corners will get dark. But that leaves undeveloped the very popular zoom range of xx-300mm lenses. For instance, the numerous 80-200mm zooms, 100-300mm, or the 28-300mm.
I know I could set any old zoom flash to the longest length and just use it, but it would still get longer range if it zoomed farther. And I know Fresnel lenses can be fitted to some flash units, but the flash and the camera don't know there's a Fresnel lens attached, so that kills the "auto" part of an auto zoom. So I wonder if there's any such thing as a 28-300mm auto zoom flash. If Pentax is reading this, it would be a really nice thing to have.
