I found this

I'm wondering if this might explain some of the difference.

Spectral sensitivity may be the next wild card I need to address for myself.

Quote Originally Posted by Tom Stanworth View Post
Spot metering is the solution, hence my use of one in the UK for landscape work. I also found HP5+ not terribly well suited to our sunless climes, with TriX having, for me, a preferable look. In bright sunny conditions I think I prefer pulled HP5+.