Spreadsheet for developing times

[david_ceruti]

I have recently started out in the darkroom and am on a steep

learning curve.

 

One of the frustrating things is trying to get an accurate reading

from the temperature/development time chart. Hasn't anyone put this

on a spreadsheet yet? Ilford hasn't and a search of the web revealed

nothing.

 

I know that I need to spend time and learn what works for me, so I

am calibrating my camera and processing times and keeping detailed

records. I guess it irritates me to mess around with a tiny chart

that doesn't even show half minutes and is almost impossible to use

for longer exposure times. A simple spreadsheet could give detailed

tables and calculate accurate times so that I would be in the

ballpark and not make unecessary mistakes before I start trying out

different times.

 

Excuse the mini rant - I am probably going to sit down and develop

the spreadsheet myself but don't want to reinvent the wheel

(assuming someone has already done so)

 

Thanks

 

David

[conrad_hoffman]

I'm a big believer in spreadsheets, but you have to realize that the process doesn't lend itself to precision beyond 15 seconds or so, and that's only with short development times. There are also other variables that aren't as easily controlled, like the age of the developer. One could build a sprreadsheet that took many factors into account, but your time might be better spent making images and working with a constant process. The most important thing is repeatability. Only if you process exactly the same way every time, will you be able to dial in any given film and developer combination successfully.

[john_stockdale2]

I have done a spreadsheet that suits my purpose. If you look at the formula near the bottom of the HC-110 page of

 

http://www.covingtoninnovations.com/hc110/

 

you will see an equation for calculating the times according to a typical set of time/temp numbers from a manufacturer, such as the Ilford graph. If you want to derive your own constant from experience instead of using the one supplied, you need a set of 2 time/temp figures. If you plug them into my spreadsheet, you will get a new value for the constant, and then use the speadsheet to find a time for a new temp.

 

Now, can I attach a spreadsheet to this posting? I'll try.

[jon_furer]

Try www.digitaltruth.com and click on massive development chart. It's a great source for many b&w films and developer combinations.

[ian_beales]

I'm very much an analog person. I created a sheet of semi-log graph paper with log time on the X-axis and temperature on the Y-axis. I manually plot the time-temperature data from the film I use (mainly Tri-X) which results in a straight line in the same manner as shown on the Ilford graphs that are available on the web.

 

In reality, I move the straight line to the left (maintaining the same slope) to suit actual conditions based on film testing. From that point onward it is a simple matter of measuring the temperature of my chemicals and looking up the appropriate development time.

 

I'll try to attach the graph which is a WordPerfect document. It does not reproduce well with Word :(

[david_ceruti]

Thanks! - you guys are great

 

David

[lowell_huff1]

We offer spread sheet processing times for most films and our chemistry, in both manual and machine processing. askus@claytonchem.com