Archived posting to the Leica Users Group, 2009/11/20

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Subject: [Leica] Thought question re antialiasing
From: grduprey at mchsi.com (grduprey at mchsi.com)
Date: Fri, 20 Nov 2009 16:48:42 +0000
References: <494971.52240.qm@web83908.mail.sp1.yahoo.com><20091120032721.GA2535@d242.scdc1.swarthmore.edu><4796FFE1-49FB-45D9-8E75-A381DCB355E3@ameritech.net><20091120035749.GB2535@d242.scdc1.swarthmore.edu><36172e5a0911192044s197d811ao879d833085c1a661@mail.gmail.com> <E8CE85D5-0958-4B15-B96E-11BDEABCCA9F@ameritech.net>

 
It may also have to do that the sensors used in the M8/9 today are, what, 
5?, 10? generations from what was used in the 14N.  A big knowledge jump 
from the 14N days.


Gene -------------- Original message from Dante Stella <dstella1 at 
ameritech.net>: --------------

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 
> > 
> >> 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
> 
> 
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information


In reply to: Message from dstella1 at ameritech.net (Dante Stella) ([Leica] Thought question re antialiasing)
Message from tgray at 125px.com (Tim Gray) ([Leica] Thought question re antialiasing)
Message from dstella1 at ameritech.net (Dante Stella) ([Leica] Thought question re antialiasing)
Message from tgray at 125px.com (Tim Gray) ([Leica] Thought question re antialiasing)
Message from hopsternew at gmail.com (Geoff Hopkinson) ([Leica] Thought question re antialiasing)
Message from dstella1 at ameritech.net (Dante Stella) ([Leica] Thought question re antialiasing)