I can't comment on Finnair but I have never had carry-on weighed. My suggestion would be to have the camera with a neck strap, get a couple of lens cases that fit on a belt or use a photo vest for some of your equipment, wear the heavy shoes, hold the tripod when checking in and put all that stuff in the bin to go through the x-ray and it may not be considered carry-on. I travel with a Tamrac camera backpack when loaded with the equipment I normally take weighs approx. 25lbs plus a carbon fiber tripod in a separate bag. So far it has not been weighed.