Microfiche trivia, my memory may be rusty
The sample microfiche I have retrieved are 4" high by 6" wide. There are
varying numbers of images placed on them. The layout of the images
indicates what magnification of the originals was used. The ones I have are
12 columns of images across by 6 rows of images down. Of the 8 microfiche
readers I have recently examined most are the 24X units. Some are dual 24X
and 48X. There are supposed to be a 72X but I haven't ever seen one.
I have examined a sample microfiche under an old microscope, vintage 1950,
and used several different magnifications.
Car parts listings are a typical usage of microfiche.
Some microfiche were designed to be COM (Computer Output Microfiche), the
images are landscape.
On my sample microfiche each minified image is about 1/2" by 3/4".
If you figure that on the 8 wide paper it takes 150dpi to accurately sample
the original page. There are therefore 1200 useful dots reduced into 1/2".
and then you need to scan the microfiche image at about 2400dpi to get an
accurate reproduction.
I'm trying a Nikon scanner at 1200dpi as an experiment, the main problem is
getting enough light through the microfiche.
YMMV
Thanks
Mike
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://www.classiccmp.org/pipermail/cctalk/attachments/20020509/8a8805ad/attachment.html
Received on Thu May 09 2002 - 15:49:24 BST