I know I could google it, but in simple terms, whats the difference between DG and APO and all the likes?
Seems that for every manufacturer, theres normally 2 or more versions of the same lens with different letters at the end. Like what does "L" stand for for canon lenses, all I know is it means "Expensive" (and presumably good too)
They can be very confusing for those who dont know, here are some catagories and their names where I know them (perhaps we could make a sticky?)
Top tier glass, usually with all the trimmings, built like tanks to survive pro-use
Canon - L
Pentax - * (the * is appended to the range name, so FA* and DA* are each the top of their respective ranges)
Sigma - EX
Tokina - AT-X
Tamron - SP
In lens sonic motors, gives faster, quieter AF
Canon - USM
Nikon - AF-S
Pentax - SDM
Sigma - HSM
uses clever glass to deal with CAPentax - ED
Sigma - APO
Tamron - LD
Crop sensor digital only designed for ~1.5x crop sensor cameras, vignetting will occur with film cameras
Canon - EF-S (cannot be mounted on full frame cameras due to shortened mirror box)
Nikon - DX
Pentax - DA
Sigma - DC
Tamron - Di (Tamron only seem to have one designation for digital optimised lenses, for both full and crop frame)
Tokina - DX
Digital Optimised Coatings, improved lens coatings to cope with increased reflection from digital sensors. Still projects full image circle for film cameras and full frame DSLRS.
Pentax - DFA, (also some DA* lenses actually project a full image circle)
Sigma - DG
Tamron - Di (Tamron only seem to have one designation for digital optimised lenses, for both full and crop frame)
Tokina - D
Those are all the ones I can think of off the top of my head, any specific queries give me a shout. Im best at Pentax and 3rd party lenses but have hung out with enough Nikon and Canon togs to have a vague idea on those too.