Hello, I have a question in regards to placing highlights in the developing stages. Over and Under developing is something new for me, I haven't tried this yet, but I'm looking forward to giving it a try.

I'm currently developing Tri-X for 10 minutes (HC-110 at 1:31) first 30 seconds of constant agitation and 3 consecutive inversions after every minute of the remaining develop time. This has given me good results, and from now on I'll be considering this my 'normal' developing time.

For discussion sake, lets say I would like to bring my highlights in my negative down by 1 stop, or 2 stops. On the zone system, lets just say the highlights are are currently in Zone 9, and I'd like to bring them down to Zone 8 or even Zone 7.



Here is where my speculation beings:

Since each zone is a full stop of light (double or 1/2 the light), would this equate to 2x or 1/2 the development time to move the highlights up or down a single stop/zone? So, instead of 10 minutes develop time, 5 minutes develop time to bring the highlights down by one stop? (And 4x or 1/4 the development time to move the highlights up or down 2 stops/zones?) Is it as linear of an equation as this? Or am I sorely off base with my speculation?

I don't shoot alot of film (usually only 2 or 4 sheets per weekend) so I don't really have alot of time/resources to do extensive testing. What I'm looking for are some suggestions as to where to start my testing, to hopefully get myself off on the right foot.

Any suggestions as to where my starting point for testing should begin? Thanks for any thoughts!