Archived posting to the Leica Users Group, 2009/11/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Kodak is a little bit cagey with the info on the offset lenses on the KAF-10500 and its bigger brother. I think the microlenses are tailored to the application. What got me thinking about this is that I have an M8 and a Kodak 14n. Neither has an AA filter, but the 14n also lacks microlenses. If you process RAW files for both through Lightroom (so you don't get contamination from any in-camera correction), the 14n will produce insoluble moire much more of the time - sometimes to the point where inducing diffraction by stopping down the lens to f/11 is the solution. On the other hand, the Leica virtually never hits this point. But given the tighter pixel pitch and even higher-resolution lenses, one would expect it to. My hypothesis (which might be wrong) is that the little lenses (completely offset or not) are acting as something of an AA filter - and what we all take to be sharper pictures from no AA filter is really higher-contrast pictures from higher-contrast lenses. Both the M8's and M9's resolutions are 73lp/mm (at least according to Reichmann), and it should be routine to cross that at wide apertures with M lenses. But the incidence of moire at any aperture is so low as to suggest that the barrier rarely gets crossed. That suggests something acting as a limiting factor on resolution. Something interesting, BTW, is the difference with and without AA filters. If it is a relatively weak filter, as on the Nikon D3, removing the AA filter actually does very little. Go here: http://bythom.com/nikond3xreview.htm And take a look at the with/without pairs for the D3 and D3x. Very interesting. Dante On Nov 19, 2009, at 11:44 PM, Geoff Hopkinson wrote: > My assumption also. Perhaps there is info on this available from Kodak, or > Dante has it already? Interesting technically anyway. > > 2009/11/20 Tim Gray <tgray at 125px.com> > >> On Thu 19, Nov'09 at 10:37 PM -0500, Dante Stella wrote: >> >>> They do span more than one pixel - that's why they're called offset. And >>> that is why I asked. >>> >> >> Ahh, I wasn't aware that they did that. I interpreted the offset >> microlenses as not being centered directly over a pixel, but still >> funneling >> in light into just one pixel. Thus, enabling light to come in at more >> oblique angles and still be captured. I drew an ascii diagram, but I'm >> sure >> most everyone's mail client will mangle it, unless you have monospaced >> fonts. >> >> ------- >> \ | >> \ | <- offset lens >> \___| >> | | <- pixel >> ---- >> As opposed to >> >> ------- >> \ / <- non-offset lens >> \___/ >> | | <- pixel >> ---- >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information >> > > > > -- > Cheers > Geoff > http://www.pbase.com/hoppyman > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information