Hi Paul, The hood on the 50-200 isn't a tulip hood (unless your definition is different than mine and that of others as well), and it's much wider at the front than it needs to be. Not only is it bulky, but designed the way it is, with a wide opening tapering down to the bayonet mount on the lens, can allow too much stray light to get in under the right circumstances. Since I don't have the hood here, I can't measure it, but I'm estimating the wide end is almost 4" in diameter, far more than it needs to be and quite inefficient. I now have fully three inches of length on the hood here with a maximum diameter at the front of only 2.5 inches. There is absolutely no vignetting with a 50mm (K50/1.2) lens at the closest focusing distance, i.e., with the lens fully extended, and every indication that the lens can be made deeper or somewhat narrower with no adverse effects.
Of course, the design of the 50-200 may be such that with so narrow and deep a hood, there may be some vignetting, yet that remains to be seen, and try as I might, I can't figure out how that could be. Shel > [Original Message] > From: Paul Stenquist <[EMAIL PROTECTED]> > To: Pentax-Discuss Mail List <pdml@pdml.net> > Date: 9/21/2006 8:34:37 PM > Subject: Re: I used a DA 50-200 today > > You might be okay with a deeper hood, but not with a smaller hood. > And I wouldn't be surprised if you saw some vignetting at 50mm with > the deeper hood. Tulip hods are the best compromise configuration for > a rectangular format zoom. Pentax seems to have a good grasp of the > design parameters that make for a good tulip hood. I doubt that a > substitute would be better. > Shel Belinkoff wrote: > > > I'd have to get used to all the things to think > > about with variable aperture. Seems that in > > order to get some semblance of stability, > > you've got to shoot at smaller aps ... > > > > Why not a smaller hood? The hood I used was > > designed for a 200mm hood? It protects better > > than the original based on preliminary tests. The > > hood that comes with the lens is designed to fit > >over the lens, and does not offer the best protection. > > Had some probs with a similar hood on the > > 16-45. I'm going to try for an even tighter, perhaps > > deeper, hood for the 50-200. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
