But DOF is not an issue for focussing - the camera focusses wide open. It doesnt stop down until you take the shot. When you talk about the subject leaving the plane of focus before the shutter fires this is shutter lag. Lens performance aside, the camer always gets the subject in focus at f2.8 if it is an f2.8 lens.
> -----Original Message----- > From: Bruce Rubenstein [mailto:[EMAIL PROTECTED]] > Sent: 11 March 2002 01:03 > To: [EMAIL PROTECTED] > Subject: RE: AF speed (was: Silly Photo.net thread) > > > The issue is Depth Of Field. Shooting wide open with long > lenses gives a very > shallow DOF. If the whole AF system (lens > speed/electronics/motor, etc.) > doesn't work fast enough, the subject can past through the > range of apperent > sharpness before the shutter fires. Before AF lenses were > stopped down for > "focus margin" for shots like this. Lens performance aside, > it's harder to get > a fast moving subject in focus at f2.8 than f11. > > > --- Rob Brigham <[EMAIL PROTECTED]> wrote: > > I dont get this question. The focussing aperture was > F/2.8, or possibly > > F/4 with the teleconvertor. Since the shutter doesnt fire > unless the > > subject is in focus, the shooting aperture is pretty much > irrelevant. > Try FREE Yahoo! Mail - the world's greatest free email! > http://mail.yahoo.com/ > - > 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 . - 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 .
