Just How Much does Agitation change contrast?

[DNG]

I have been developing for a while. (from 15 years old to about 23 years old, for a few years in my 30's, and for the a last few months - I'm 58 now)

I have noticed that increasing developing time is much more effective in increasing contrast over increasing the agitation routine.

1. Is there a reason to choose one method over the other?
2. What are the Pro/Cons of each method?

 

[Chriscrawfordphoto]

Changing time is more consistent, and produces less grain. If you want to see the difference agitation makes, look at some of Kodak's tech publications on their films. They give developing times for hand-processing with agitation every 30 seconds, and they also give times for rotary processors, which give constant agitation. There isn't a great difference...10-20% depending on the film and developer.

 

[DNG]

That is the method I use. and I can save the new time in the Massive Developer Chart APP in my "Favorite's Tab.

I did know that it helps keep the grain down though. I agitate every 2min for 10s. My times are around 10min-13min with Rodinal 1:25 for the most part.

 

[sevo]

It really depends on the developer. Some have enough concentration that the amount of developer initially soaking into the emulsion is all that is needed - the main reason why you have to agitate classic large tank developers is that the film would otherwise grow bromide vanes. As far as development is concerned, agitating them won't cause much change to contrast, saturation or time - as Chris pointed out, the time difference between different agitation regimes tends to be lower than that for a 2°C temperature increase.

With low-concentration (typically one-shot) developers, agitation is far more important - stand developing with them will create visibly odd mask-like effects.

 

[Trius]

I think agitation has more affect on grain structure than contrast. But that's just a "think" ... haven't done rigid, controlled tests.

 

[ChrisN]

I've been using continuous agitation (rotating drum) for a while, and I was initially surprised at how little change there is compared with traditional agitation (ie 4 inversions by hand every minute).