Quote Originally Posted by RattyMouse View Post
Thank you very much (and everyone else too, this group is just great!). So to get ISO100, just add 30 seconds! Seems simple enough. Great help, thanks so much!

Not exactly that simple.

The actual speed point may not change, but a 1/3 stop "error" is hardly a big worry on negative film.

Personally though, as a rule, if there is going to be a discrepancy, I always err on the side of extra exposure for all my negatives.

Exposure controls how much detail you get in the shadows,

Fuji is essentially suggesting that to get the same shadow detail when using HC110 you should use a bit more exposure than if you were using D76.

Extra development time is an option but it doesn't markedly change the speed point of a given film/developer combo, what it does do is change how steep the film curve is, a steeper curve (extra development/pushing/plus development) naturally prints less detail on a given paper or an adjustment in paper contrast may be needed.

Extra development may or may not be beneficial for a given shot or your photography in general. You have to decide that for yourself.