I don't worry too much about the balance. If you have a ball head capable of properly supporting a longish lens, it should lock securely no matter what.
A ball head is not generally the best for a long tele lens. I've used one with my mirror 600mm because it's light and short, but it's suboptimal. The one I like to use the most is the Arca-Swiss Monoball P0 Hybrid ... this allows me to rough in a position and then adjust the position with precision using the two goniometers and rotating top mount. But it's an expensive head (about $900). It works well for astrophotography of bright subjects (the Moon and Jupiter, for example) where I can usually get away with a sunlight exposure... If I were doing long exposures with dim subjects, I'd buy an equatorial clock drive mount. For a 400-600 mm refractor lens like the big Pentax guns, a gimbal mount is the right support. And with these, getting the balance point adjusted close to the center of mass makes it easier to control them as they are designed for movement and panning ... a long mounting plate helps. (The plate I have for my Olympus 50-200mm lens (often used with the matched 1.4x teleconverter so an effective 560ish mm lens) is about seven inches long because that lens telescopes about 5 inches through the zoom range and I often want to adjust it if I'm trying to track a moving subject. I use the Acratech GP1 head in a "limited" gimbal mount orientation for that lens. G -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
