Quote Originally Posted by Willie View Post
Does Reciprocity for long exposures keep going on - forever?

So, exposures of many minutes to hours - some "slop factor" in the mix. Not like 1/125 second at all.

Any information about very long exposures and reciprocity you can direct me to?
I do a lot of long exposure photography, in the early days using McSavveny's unusual sequence of developing with HC 110. Today, the HC 110 is a poor developer for that type of extended time in chemistry. There is a host of reasons why Pyro developers are perfectly suited for long times in solution. After trying several notable photogs reciprocity suggestions I have found the Ilford factor system to be quite accurate, possibly a touch too much exposure when you get into more than 60 minute exposure times.