Notes on using film Pentax lenses with the digital Pentax *ist line.
These comments are collected from the internet from various forums.
 - Philip Wilk August 2006  

In general, a lense made for the Pentax film cameras will function as the
same lens magnified by 1.5x.

SMC Super Multi Coat
P	Pentax

Lens Prefixes
-------------
*  - The "Star" designation indicates the use of particularly high
     quality glass in the lens.  The FA* lenses also have an auto-manual
     focus switch on the lens barrel.
A -  A manual focus lens supporting automatic aperture selection
     capability on bodies which support this.
F  - An Auto-focus lens with all the capabilities of the A lenses.  F
     lenses also report their focal length and focus distance to the
     camera.
FA - A newer auto-focus lens with all the capabilities of an F lens with
     an added MTF chip.  The older FA lenses also incorporate the
     "power-zoom" feature while the newer ones do not.
M  - Manual focus lenses designed for the M series of cameras.
K or nothing - The first of the bayonet mount lenses, often a screw-mount
     design adapted to the k-mount.
Takumar - Has two meanings:
  1) On a screw-mount lens indicates a high end design.
  2) On a k-mount lens indicates a bargain quality lens with single
     coating only (not SMC).
  Super Takumar - Indicates that the screw-mount lens has a fully
     automatic diaphragm.
  Takumar lenses are single coated unless marked SMC.
  
MTF chip?
J? no manual aperature setting allowed.