It gets a bit lonely as (probably) the only photographer here using film 
but even digital people should find things of interest here. From my point of view, there are lots of older technical sheets and formulae; for everyone (with that sort of bent!) there are books on photographic optics. Those with an interest in film and/or old processes may find the books submitted by this chap a very useful way in:
The archive always provides a list of similar items at the bottom of the page, so do scroll down.
but even digital people should find things of interest here. From my point of view, there are lots of older technical sheets and formulae; for everyone (with that sort of bent!) there are books on photographic optics. Those with an interest in film and/or old processes may find the books submitted by this chap a very useful way in:The archive always provides a list of similar items at the bottom of the page, so do scroll down.