Scanning

[Larry]

I am about to undertake the scanning of photos going back to the
early/middle 50s. The default resolution is 150. Is that okay or do I need
to increase it to 300 or more. The photos will be b/w and colour.

[Paul]

Have a little go. The higher the res the more you have to work with,
but only you can decide what is enough.

[Eric]

Depends on what size they currently are versus what size you'll want to
print them at in the future. Otherwise, talking about dpi is meaningless.

[Bob]

It all depends on what you want to do with the scanned image.
But without knowing that, I'd suggest scanning at 300 pixels/inch.
Your original photos do not have more resolution than 300ppi. Therefore
it is pointless to scan them at anything greater than that.
Once you have the digital info, you can resample the image to whatever
size you want.

[David]

Are you scanning film (negatives or slides) or prints?

150 or 300 are decent values for prints (anything over 300 is almost
certainly a waste of time, unless you have exceptionally fine glossy
prints). They're grotesquely inadequate for film.

What do you plan to *do* with these scans? Are they intended to be
final archival scans, or do you just need them for a web site, or is
it some intermediate plan?

The two basic approaches to scanning are "get every bit of information
I can out of the picture" and "get the amount of information I need to
do X".