Please recommend me a developing time

[JeremyLangford]

I have recently been shooting Arista ISO 400 B&W film and developing it in Kodak HC-110 for 6.5 minutes, agitating every minute, and they turn out perfect.

However, now I need to push the same 400 speed film to 1600 and use the same HC-110 developer.

I was thinking maybe I should double the developing time to 13 minutes because I am pushing 2 stops. Does this sound right or wrong?

Also, I have no idea how much or how little I should be agitating for a 2 stop push.

Please just recommend me a develop time, and an idea on how much agitation should be involved.

I looked on the Digital-Truth Developing Time chart and they dont have times for Arista film.

 

[meeker]

Arista films are rebadged film from major manufacturers. Digital Truth as a chart that shows which film the Arista film corresponds to.

 

[JeremyLangford]

Arista films are rebadged film from major manufacturers. Digital Truth as a chart that shows which film the Arista film corresponds to.

But It doesnt show agitation time.

Id just like your guys recommendations.

 

[navilluspm]

Whether in Photoshop or on the enlarger, it is always easier to add contrast than reduce it. Kodak usually recommends 5 seconds every 30 seconds and Ilford 10 seconds every minute. These are good starting points. If you shot something in flat light, use these times. If you shot in very contrasty light to begin with, then maybe 5 seconds every minute, or a few twists every minute, minute and a half.


But I am a beginner too, so take my advice with a grain of salt. 😱

 

[JeremyLangford]

So I guess the question should be, what does agitation do to the picture? Does it add contrast? Why do we need to agitate?

 

[EmilGil]

Agitation moves the chemistry around to prevent it from exhaustion.

Imagine small patches of film, one heavily exposed (highlight) and one less exposed (shadow). If you don't agitate, the developer will exhaust locally in the highlight patch but not in the shadow patch as there are less silver ions to develop there. By agitating, you supply both patches with fresher chemistry to increase the development activity. It might not make a huge difference in the shadow patch but it definately will in the highlight patch. If you agitate too much, this patch will block up completely and you will lose all details.

Some photographers practise 'stand development' with a very dilute developer for a long time (sometimes over an hour) where they agitate next to nothing. This is said to increase the shadow detail with out losing the highlights.

I use the agitation recommended above, 5sec every 30s after agitating the first 30s, and control contrast through development time/EI.