John, do you believe that constant aperture zoom lenses are just as easy to focus at the widest end as at the longest end? I don't and so far no one else has posted that they believe that either. How can you explain this well known phenomenon? jco
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Francis Sent: Tuesday, November 14, 2006 12:37 PM To: Pentax-Discuss Mail List Subject: Re: Using a Super Tak w/ istDS- A challange to the list? On Tue, Nov 14, 2006 at 08:25:52AM -0500, Cory Papenfuss wrote: > > > You're correct on this JCO. Bill Robb is bating you. Ignore him and > > he'll stop. > > Paul > > Agreed. > > Everything else being equal (aperture, contrast, resolution, > helical gear cut, etc), a longer focal length (e.g. 105mm) will have a > higher "focusing sensitivity" than a wide angle (e.g. 35mm). That's just > plain physics. But that still doesn't necessarily make them easier to focus, which I believe was the original contention. In fact in at least one way it makes them harder to focus - it's too easy to overshoot, or to focus on the wrong place (especially if you are trying to pre-focus in anticipation of a moving object coming into your composition). -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
