Theory is a statement of how and why particular facts are related. In the context of JAPB, theory is all that which is not directly pertaining to specific items of gear, but more to how gear relates to other gear (in the context of taking photos).

See below for a list of the more detailed musings. You can also look at our glossary for explanations of the more simple* concepts and terms.

* simple, as in “explainable in a few paragraphs”.

Articles on lens mounts:

Articles on lens mounts in general:
An introduction to lens mounts
Identifying a lens mount
Articles detailing specific lens mounts:
Canon EF
Canon FL, FD and newFD
Contax G
Contax / Kiev
Fujica X
Icarex BM
Konica AR
Konica F
LTM (Leica Thread Mount)
Mamiya Z
Minolta A (Sony A)
Minolta SR
Nikon F
Olympus OM
Pentacon Six
Pentax K
Petri FT
Praktica B
Rollei QBM
Topcon UV
Yashica AF
(and more to come)

JAPB series on optical flaws and aberrations:

Distortions (optical)
Veiling and Ghosting (flare)
Atypical ghosts
Spherical aberration
Focus shift
Comatic aberration (‘Coma’)
Chromatic aberrations
Field curvature
Uniform colour casts
Partial colour casts
Diffraction (even though it’s not an optical flaw or aberration)

JAPB series on exposure

The components of exposure (and the side-effects)
Working with Exposure (in practice)
Various approaches to exposure automation
EV tables

Articles that are not part of a series:

Legacy, Classic and Vintage lenses? What are those?
Practicalities of adapting lenses