Due to differences in cameras, lenses, developing techniques and exposure conditions, the above times should only be used as guidelines for your own exposures.
Always expose for the desired shadow detail and develop for the desired separation of high values.
Times given are generally for development of 120 roll film in small tanks (and may be used as starting points for tray development of sheet film), optimized for enlarging
with a cold light head. Since I presoak my film, I add 30 seconds of developing time that I do not record (assuming it takes that long for the developer to diffuse into the swollen emulsion). My times are generally
longer than those provided by Gordon Hutchings (I agitate less, optimize for cold light, and seek maximum shadow detail).
I give continuous agitation for the first 30 seconds of development, then 5 seconds of agitation every 30 seconds thereafter. Gordon Hutchings recommends at least 3
or 4 agitations per minute to prevent uneven development in roll film tanks, but I have not had problems with my method.
(See My Development Techniques.)
The standard dilution for PMK is 1 part A to 2 parts B to 100 parts water (1:2:100). I have found that, as a general rule, if developing times are too long, you can
double the amount of A and B solutions (2:4:100 or 1:2:50) and reduce development time to 3/5ths normal.