RE: filmscanners:minolta and med format (PPI BS)

["Austin Franklin" <darkroom@ix.netcom.com>]

Erik,

> The Minolta DiMAGE Scan Multi PRO does 4800 PPI on 135 film, and 3200 on
> 120. Scanning at 4800 PPI may give som additional resolution in one
> direction, depending on the physical size of the pixel. The other
> direction
> is entirely interpolated.

That's not what I understand.  I believe the magnification is changed to get
the horizontal resolution, and the vertical resolution (stepping of the
film) is done at 3200 or 4800...since the stepper can move at 9600, that
allows both resolutions to be stepped.  I believe Ed Hamrick stated that
also in this newsgroup.

> I'd be surprised if there was any
> practical (that
> is visible) advantage of using 4800 PPI compared with 3200 PPI.

Sure there is a practical advantage of higher resolution (if the film has it
to give), it depends on the size of your output...

> These curves go to 40 lpmm (which corresponds to 2032 PPI)

Well, actually it takes slightly more than 2x to scan, so if you want to
RELIABLY scan 40lp/mm, you need slightly more than 4000SPI.

Regards,

Austin