If you expect you'll use something, and it fits in the canoe, why not take it and leave the guilt at home instead?

My photo stuff is 13 - 14 pounds incl. tripod and that's historically pretty minimal for me. Carrying water is what I'll grumble most about but it's nice to have after lugging all that [stuff] around for a while.

FWIW - three loaded portage trips, 30 - 50 pounds each is easier/safer when solo and turns two not real enjoyable trudges into a continuous pleasurable walk in the woods and you can take whatever fits in the canoe.

Even with plenty of room leftover, I don't take binocs or even a monocular anymore simply because I rarely use it and it always seems to be packed a zipper or two deep because I normally allow myself only so much stuff out at one time. It's great when someone else brings a nice pair and/or you already know where the portages are though. ;)