Vivitar 285 can still be found second hand, it is nearly as old as the hills, is powerful, reliable and very controllable. BUT. make sure you get one with low trigger voltage otherwise you will fry your camera electronics.
Thanks for the tip

Does it work with P-TTL on K-30?
Massao
--
First camera: Canon FTB; First autofocus SLR camera: Pentax; First Nikon: F601 (N6006); First digital camera: Sony DSC-W5; First DSLR: Nikon D70; First mirrorless ICL camera: Samsung nx11
I'd give those old flashes a miss on a modern DSLR, as the guy says they may fry you camera. I do own several old manual adjust lenses, the Pentax ones are safe to use but I only use them on film cameras.
The Metz 50 AF-1 and other models read the focal length of your lens and automatically adjust (shape and zoom) the flash for the lens. Even with zoom lenses with focal length read-out it will adjust to the zoomed length. The Metz also has a built-in pull-out wide angle 12mm focal length diffuser and a reflector. This gives such a wide spread uniform illumination when using the DA15 f4.
You can pick Metz or other modern flashes on the used market for great prices and often in mint condition.