Fiche scanning (was Re: [Simh] Listings of XXDP test and maindec's for 11/70)

[Jim Battle]

Jan-Benedict Glaw wrote:
> On Tue, 2009-04-14 10:52:00 -0500, Jules Richardson <jules.richardson99 at gmail.com> wrote:
>> The DEC ones I've seen are extremely high resolution - from memory, 
>> something like 11 x 13 A4 pages on a fiche around 1" x 1.5".
> 
> If this is right, then there's a scale factor of about 1:90 to 1:100
> involved.  That should tell everybody why even a good consumer-grade
> scanner will not do the job. To get the equivalent of a 300dpi scan,
> you'd need to have about 30000dpi. Nothing any el-cheapo scanner could
> handle. (Let alone the problem of getting the sheet properly into the
> light's focus.)

you are confusing linear pixel density with areal pixel density.

the 11"x13" fitting in 1"x1.5" implies a 11:1 scaling in density, so 300 
dpi would be 3300 dpi.  still very high for typical consumer grade 
scanners.  I believe 2400 dpi actual (not interpolated) is available on 
decent models, though.