Here you will find some mathematical tables and formulas to help get on with stuff.
f/stop Calculator
When working in the darkroom you might need quick access to relevant exposure times based off of your current time and adaption due to multigrade filters. Here is a simple calculator to help you get your desired exposure times when working with f/stop increments (strongly recommened). This may also come in handy when making your own greyscale rulers for reference and more economical work.
f/Stop Exposure Calculator
Exposure Times (in seconds): —
Stop Differences (in seconds): —
Exposure transposition
Should fixed exposure times for overall exposure, multigrade filtering or dodging need to be extended, for example when larger prints are being made or less sensitive paper is being used, it is helpful to proportionally transpose the previous times. For this purpose up to four different and linked exposure times can be provided to be extended as per a new global exposure time in the following module:
Exposure Time Transposition Calculator
New Exposure Times: —