I've haven't run across a modern large format book that didn't end up annoying me (though there is some value in most of them). Some people do like the Simmons book. Closest for me would be the Ansel Adams "The Camera" from his classic "Basic Photo Series". I put the titles in quotes to indicate titles, but actually wrote them from memory, so they might not be exact. The other book I really liked was the old Navy training manuals. They are commonly available cheap. I'll dig up a link if you are interested. They are very old fashioned non-arty books, but that's part of what I like about them. Just good solid basic practical information.
Originally Posted by fanuja
I do have some thoughts on the lens. The series Ia I am familiar with is very similar to a Protar design and should be a very good lens when you use both cells. You convert it to different focal lengths by removing on or the other lens cell. I don't think any of these convertible lenses will be very good converted on 2 1/4 x 3 1/4. On 8x10 they are fine, but the usually won't take much enlargement.
The qualifier to all that is that the lenses I'm familiar with are f6.8 and triple convertible (each cell is a different focal length). I suspect yours might be a double convertible lens where both cells are the same. That symmetrical design would account for the difference in f stop. If yours is indeed a three focal length lens, then it may be something different (probably a lesser Rapid Rectilinear type design). Maybe someone else knows for sure (or I might have the info somewhere in old literature.