Interesting concept, John. Providing the evidence that proves my claim. Perhaps you should have done the math yourself before you offered an opinion.
The biggest CoC that is perceived as sharp is 1/100in, and the standard print size for judging it is 8in x 10in (20.3cm x 25.4cm). So it follows that the biggest CoC at the sensor that will enlarge to 1/100in at 12.69X enlargement is 0.01in / 12.69, or just under 8/10,000in. But you say that the Bayer interpolation increases CoC "on the film" (I suppose you mean at the sensor) by up to 1/2000in. That's 2.5 times more than the threshold at which apparently sharp details become apparently unsharp. What point were you trying to make? It seems that these numbers prove that NOTHING from an APS Bayer array sensor should be sharp. IMO these numbers prove that everything up to that huge CoC requires sharpening in software to bring it back to an acceptable apparent sharpness. IOW the CoC (or apparent CoC in any case) needs to be reduced at least 2.5 times to bring an APS digital capture back to the outer limits of sharpness. This means that any out of focus details larger than 8/10,000in and smaller than 1/2,000in, which SHOULD appear unfocused, will be caught up in the sharpening. I'll have to leave it to a better mathematical mind than mine to determine the magnitude of the effect, if anyone even cares. It does appear to demonstrate that Bayer sensors produce greater DOF than film of an equal format. But please be careful when you accuse someone of operating under a flawed premise, the claim is just as easily turned back your way. regards, Anthony Farr > -----Original Message----- > From: John Francis [mailto:[EMAIL PROTECTED] > Sent: Monday, 18 July 2005 7:03 AM > To: [email protected] > Subject: Re: Theory of Equivalency > > On Sun, Jul 17, 2005 at 03:17:13PM +1000, Anthony Farr wrote: > > That's correct William. I meant to point out that the dof effects being > > witnessed were not a consequence of dof theory, but a consequence of the > > digital capture process. > > Unfortunately your entire argument was based on a flawed premise. > Bayer interpolation increases the CoC on the film by at most 1/2000" > with the *ist-D sensor - it doesn't spread across large sensor areas. > And that's a maximum; realistically you can count on maybe half that. > That means the CoC increases by only a small percentage, so the effects > of the digital capture process are (as Herb and others have noted) only > second-order effects, not the dominant cause as you seem to suggest.
