I have the F3 (two of them) and an F5, and I love the F3 if only for the feeling of the frame advance lever. It's so silky smooth. But I am looking at a F2 Titan with the DP-12 prism in new condition. For my money, the F2 could probably go anywhere and work well -- from -30 below zero to outer space. It's built that well. The F3 is great, but more electronics and perhaps a little more fragile long term. The F2 is a tank that could literally work forever.