Hi David,

yes, from a parallel posting I noted:
the canon 10d is a 6.3 MP with 22.7x15.1mm (1.6X) sensor if sources are
right ;-) You can expect a maximum of circa 68 lpmm resolution. endquote

so 48 lpmm allowing for anti-aliasing filter and lens systems resolution
calculations (and that we are using only the center of high end canon
lenses ;-) makes getting 48 lpmm starting with a sensor spaced to get 68
lpmm equiv. seem reasonable. As I noted, claims of 75 lpmm may reflect
post-image processing by in-camera software, or subjective chart reading
or ?? I generally state 40-50+ lpmm due to these sensor anti-aliasing
issues as the effective DSLR system resolutions, so this is reasonable ;-)

Some context - I have noted how hard it is to break the 50 lpmm "barrier"
Erwin Puts, the noted leica lens testing guru, has suggested that 40 lpmm
is even more likely a barrier past which few amateur photographers reach,
unless they master good technique (tripod etc.) and careful (slow) film
selection etc.

So it isn't revolutionary to me that lots of folks find digicams and even
pricey 6 to 8 MP DSLRs are delivering - at 42 to 48 lpmm - pretty decent
photos comparable to what they achieved with film cameras in the past.
They weren't beating 40 or 50 lpmm in the past, and they aren't doing much
worse with digital photography, so why not be happy? ;-)

With good technique, tripods, and slow 100 ISO film and fixed lenses, they
could probably have beaten 60+ lpmm (at least centrally). And with better
lenses, then 80 lpmm and beyond are possible with slow films ;-) But maybe
5% of amateurs that I have seen are using a tripod, so the vast majority
are understandably happy with 40-50 lpmm equiv. achieved with digicams ;-)

But that also doesn't help those of us shooting MF for more quality ;-( We
aren't satisfied with 40-50 lpmm handheld shots on 35mm SLRs with fast
400-800+ ISO films and slow zone AF etc. ;-) So for us, it should take a
64 MP sensor to make us as happy as the 35mm full format 16MP DSLR crowd
at 60+ lpmm (on film equiv.).

again, my $.02 ;-)

bobm
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* Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 *
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