Dr. Focus said thanks for the link. He thinks you've mentioned it
before but Dr. Focus must have forgotten to log it. Just like me he
forgets a lot these days. :-)
a partially slumbering
Chuck Norcutt
usher99@xxxxxxx wrote:
> Edisonian approach Schnozz writes:
>
> " Moose mentioned something about lenses. I've spouted off on this
> before, so I won't reopen that wormy can, but will say thay my
> PanaLeica lens is one of those lenses which definitely produces a
> greater USABLE DoF than other lenses at the same focal length and
> aperture. I know full well what the numbers say, but side-by-side
> images tell a different story.
>
> AG
>
> Not sure the can is that wormy. Have seen one example of different
> apparent DOF with two lenses at same aperture on same shot on FM that
> was a very small sample size (n=1) but looked real. (One I think was
> a zoom and other experimental design problems, but still)
>
> Ideal lenses are used to construct the tables/calculators and do not
> consider colors, aberrations, diffraction. The CoC is a disk of
> even brightness. The distribution of brightness, however, is usually
> uneven. Some modest vignetting (often fixed by lens/cam cpu)
> can effect the effect pupil size and inc dof at the edges. (Is this
> more imp't in MFT format?) Aberrations affect the type and relative
> degree of blurriness in front of and behind the focal plane. Color
> effects--- haven't seen much data on that either??
>
> To quote Nasse " The usual tables and calculators therefore provide
> for some useful tools for practice, but they should not be taken too
> seriously."
>
> So, I'll take AG's observations at face value, unless proven otherwise.
>
> (see article by Nasse at Zeiss) http://tinyurl.com/yykxrhd
>
>
> Perhaps this will waken the long lost Dr. Focus out of his slumber.
>
> A believer in Not all lens fuzzy is created equal, Mike
--
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/
|