Rob, do I read you right to say that a lens doesn't need to be _razor_ sharp as long as it's well corrected for chromatic aberrations? Jostein
----- Original Message ----- From: "Rob Studdert" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, June 21, 2004 12:49 AM Subject: Re: Diffraction, F stop, and lens length > On 20 Jun 2004 at 10:50, Joseph Tainter wrote: > > > Interesting. Pentax thinks that the DA 16-45 gives its best mtf > > performance wide open (f4.0) between 16 and 24 mm., and f4.5 thereafter. > > So is the DA 16-45 a diffraction limited lens? And in terms of everyday > > shooting, what does that mean? (I've used it at f16 when I wanted DOF, > > and that the results were stunning.) > > The sensor in the *ist D is more sensitive to colour convergence errors than > absolute sharpness, the sensor is really quite low resolution relative to film. > Plus MTF is generally not a broad-band measure, it's generally at a specific > colour, as such it's very difficult to relate MTF to absolute sharpness > performance particularly relative to Bayer sensor based digital cameras. > > > Rob Studdert > HURSTVILLE AUSTRALIA > Tel +61-2-9554-4110 > UTC(GMT) +10 Hours > [EMAIL PROTECTED] > http://members.ozemail.com.au/~distudio/publications/ > Pentax user since 1986, PDMLer since 1998 >
