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filmscanners: ICE & GEM Resolution Test on Nikon IV




>Now I wonder if Mike Duncan's gonna post SFR data for ICE Normal and ICE
>Fine on film in the FH3 or slides in the MA20...
>
>Jawed

The frequencies (cycles/in) at which SFR are 50% & 10% with Kodak Max400 are:

                                50%     10%
___________________________________________
NS3.1 no ICE                    295     690
NS3.1 ICE normal                272     630
NS3.1 ICE fine                  216     520
NS3.1 ICE Normal GEM 3          238     540
VS7.17 Bright 0.5 no IR         250     550
VS7.17 Bright 1 no IR           183     470
VS7.17 Bright 1 IR filter       182     470

The gray mapping of intensities effects the measured SFR.  NS3.1 has a more
contrasty mapping than VS.  Contrasty images appear sharper and measure
sharper unless the gray mapping is calibrated.  Note that a VS brightness
of 0.5 gives a higher SFR frequency than the default 1.  To answer the
burning question, ICE degrades sharpness while VS IR filter does not, at
least on Kodak Max400. Both ICE and VS IR filter blur Kodachrome, but VS
blurs less.

 Also note these numbers include the response of
Kodak Max400 and my Canon FD 50mm F3.5 macro lens stopped down to F9.5 and
tripod mounted.  The 50% SFR indicates sharpness, while the 10% SFR
indicate resolution.

Note that SFR is the spectrum of a slanted edge and gives a more
conservative number than MTF using sinewaves.  For comparison, the 50%
response with no ICE is 500 cycles/in using MTF and 300 cycles/in using
SFR.

Mike Duncan





 




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