filmscanners: RE: dpi question (was: Beginner's question on which scanner to chose)

["Oostrom, Jerry" <Jerry.Oostrom@Alcatel.nl>]

> -----Original Message-----
> From: patton paul [SMTP:ppatton@ux1.cso.uiuc.edu]
> Sent: Monday, February 12, 2001 4:41 AM
> To:   filmscanners@halftone.co.uk
> Subject:      Re: filmscanners: Beginner's question on which scanner to
> chose
> 
> On Mon, 12 Feb 2001, Armando A. Cottim wrote:
> 
> > Hi guys.
> > Sorry for this question.
> > I notice that your posts are all so high leveled that I almost feel
> ashamed 
> > for such a beginner's question but ... here it goes.
> > 
> > I 'm considering the acquisition of a scanner to scan slides for my
> magazine.
> > I've been given several options.
> > (Please consider that Portugal is not the best place to get the ultimate
> 
> > machine just by going to the shop) :-(
> > 
> > First of all I was shown the Epson 1640 Photo (which is a flatbed and is
> 
> > said to scan 1600x3200dpi)
> 
> What does 1600x3200dpi mean?  Does it scan at 1600 dpi along one dimension
> and 3200 dpi along the perpendicular dimension?  I've also been puzzled by
> a similar claim on Epson's website.  It gives a maximum print resolution
> for the Epson 1270 photo quality printer of 1440x720 dpi
> -Paul Patton
        [Oostrom, Jerry]  With all such measures I always assume that the
smaller number is the real resolution in one direction which I think is more
important: 1600dpi for the optical unit in this example and 720dpi for the
individual ink jets.  The larger number just states how precise the stepper
motor can position the CCD array or the ink jet array. Normally the stepper
motor positions it only perpendicular to the axis in which the array is
placed.
        But who knows, maybe that somebody implemented the use of two
stepper motors active on different axes, one perhaps being a piezo element
that just shifts the (optical/inkjet) array, thereby creating greater
resolution. No idea what dpi 'formulation' you would get then and if you can
derive the resolution of the (optical/ink jet) array only from those .