[ubuntu-uk] scanning old photographs

[Tim Powys-Lybbe]

On 30 Aug at 12:33, Yorvyk <yorvik.ubunto at googlemail.com> wrote:

> On Sat, 28 Aug 2010 10:34:20 +0100 Norman Silverstone
> <norman at littletank.org> wrote:
> 
> > I have been asked to help a local historical society to digitise a
> > collection of old photographs and documents and my old flatbed
> > scanner will not be good enough for this project. I am not
> > interested in speed or copying slides but would like an optical
> > resolution of, say, 600 pixels per inch. Naturally, I have looked at
> > what is for sale but I believe there is nothing better that a
> > personal recommendation.
> > 
> > Your suggestions will be very much appreciated.
> > 
> > Norman
> > 
> > 
> Surprised you’ve got no responses to this. Why will your old scanner
> not be good enough? I use a 10+ year old Agfa Snapscan 1212µ for this
> sort of thing with out any problems.

I'm not sure the problem has been fully appreciated.

Let's say that the objective is to obtain slides that will print well on
A4 paper.  Printing needs at least 300 dots per inch for adequate
clarity, some can easily see that 600 dots per inch is better and is
barely pixellated ('dotted').  If you need 600 dots per inch on the
print, then double the following figures.

A4 printed in portrait mode is 10 inches wide, so the file image must be
3000 pixels wide.

The OP says he wishes to scan slides.  So he must produce file images
that are at least 3000 pixels across on the shorter dimension.  My
memory is that slides are on 35 mm film and this is the shorter
dimension.  35mm is 1.4ins (to the nearest tenth).  So the scanner must
produce 3000 pixels from this 1.4 ins, which is 2,100 dots per inch.

So I conclude that an old scanner very definitely will not be good
enough.

Some years ago I bought an EPSON 4870 PHOTO scanner which would do 4800
dots per inch.  It did the job on the ancient slides I had to take
copies of and continues to work well (on both Windows and Mac, not sure
about Ubuntu).  This scanner is now out of date but I think EPSON has
produced successors that do the same job.

-- 
Tim Powys-Lybbe                                           tim at powys.org
             for a miscellany of bygones: http://powys.org/