Ed Mathews wrote: > I mentioned that the 77 yields nice > bokeh, with some football (American football) shaped highlights. Nobody > commented about that, and probably nobody understood what I meant. So I > thought I'd take a picture of my Christmas tree lights out of focus to > show you.
I think all lenses do it - at least all the ones I've looked at (its less pronounced with longer lenses). My theory is that its caused by an internal vignetting. Look into the lens and swing it around, you won't see a perfect circle through the elements from all angles :) It follows that if I'm right, the effect would diminish when using lenses with a larger image circle. The effect goes away when stopped down, as you've noticed. Cheers, - Dave David A. Mann, B.E. (Elec) "Why is it that if an adult behaves like a child they lock him up, while children are allowed to run free on the streets?" -- Garfield - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
