Ok.. NOW I get it :-) Thanks for the explanation Bob..
Cheers, Dave Original Message: ----------------- From: Bob Blakely [EMAIL PROTECTED] Date: Tue, 30 Jul 2002 09:47:47 -0700 To: [EMAIL PROTECTED] Subject: Re: Pentax A-35-105/3.5 Zoom Focusing Question This is an excellent zoom lens and the focus does track very well through the zoom range. Since the aperture remains constant through the zoom range, depth of field diminishes as you zoom in from 35 to 105 mm. The narrow DOF makes critical focus easier. At 35 mm, the DOF is wide and critical focus is more difficult, but it usually doesn't matter as much because the DOF is very wide (compared to DOF at 105 mm). What I'm saying is that the focus doesn't change when you focus at 35 or 50 mm and zoom in to 105mm. I'm just saying critical focus acceptable at 50 mm is easier done at 105mm because of the narrower DOF. The SMCA 70-210 f/4 is the same way. Regards, Bob... ------------------------------- "In the carboniferous epoch we were promised perpetual peace. They swore if we gave up our weapons that the wars of the tribes would cease. But when we disarmed they sold us, and delivered us, bound, to our foe. And the gods of the copybook headings said, 'Stick to the devil you know.' " -------------------------------------------------------------------- mail2web - Check your email from the web at http://mail2web.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 .
