Temperature vs. Dev. Time

[theshotsofwhiskey]

Hi All,

So, the interwebs has an abundance of information and opinions on developing black and white film. I have an app that does the math for all my developing factors. I double check it with the dev chart to make sure it's accurate.

It's been a little warmer lately and my chemicals sit at 23C. My question is as long as I factor in the higher temperature and shorten my dev time accordingly, will I get the same results as if I lowered my chemicals to 20C?

Is it as simple as correctly using the math, or is there something to having everything at 20C?

Thanks in advance!

 

[Roger Hicks]

Hi All,

So, the interwebs has an abundance of information and opinions on developing black and white film. I have an app that does the math for all my developing factors. I double check it with the dev chart to make sure it's accurate.

It's been a little warmer lately and my chemicals sit at 23C. My question is as long as I factor in the higher temperature and shorten my dev time accordingly, will I get the same results as if I lowered my chemicals to 20C?

Is it as simple as correctly using the math, or is there something to having everything at 20C?

Thanks in advance!

Precise equivalents are not possible. At different temperatures, different developing agents are more or less active than one another, and the way in which they interact changes. Thus, a "pure" time/temperature Arrhenius adjustment does not reflect the real world.

It is however an entirely legitimate question whether anyone could see or measure the difference if they were not forewarned. My suspicion is "very rarely, across the usual range of temperatures, but it depends on the film, the exposure, the subject and the developer".

In other words, don't dismiss it in all cases, but don't hesitate to dismiss it a lot of the time.

Cheers,

R.

 

[theshotsofwhiskey]

Thank you! That helps a lot. Now, I can eliminate that (in most cases) from my problem solving when my film doesn't come out right. I'm learning a lot through trial and error, but it helps to clarify these things with others.

 

[ktmrider]

It is funny but all the times I see listed today are for 68 degrees. Back in the late 60's and early 70's when I shot TriX for a living, the data sheets listed a range of temps and the correct time. If memory serves, the range usually listed was from mid 60's to 80.

 

[Chriscrawfordphoto]

Kodak gives times for their films and developers at temps of 68, 70, 72, and 75 degrees. I've found that with Kodak films and developers, I get identical results at all temps, so long as I use the correct time for the temperature I choose.

I often use other films and developers, and have tested to find times for them at different temps. Same thing, results are the same as long as I use the right developing time for the temp I am using.

There are some who claim that Rodinal gets grainier at temps higher than 68. I have not found that to be true, and often use Rodinal at 75 degrees in the summer because the tap water in Indiana is that hot in the summer. My results are no grainier than what I get in winter at 68 degrees. I suspect those who think they're getting more grain are overdeveloping at higher temperatures.

 

[theshotsofwhiskey]

Awesome! Thank you. These were what I was looking for, but couldn't find specific answers to.

 

[Photo_Smith]

I use this:
http://www.ilfordphoto.com/Webfiles/2006210208211880.pdf

 

[theshotsofwhiskey]

Favorited, thank you!