Last year I trekked up Ben Nevis (cos it woz there) and took my camera with me with the 14-42 attached. I thought that all I was going to be snapping were landscapes but after I'd reached the top and was on the way down again I came across a snow bunting. If I'd brought the 300mm I wouldn't have had to creep across the boulder-field on seriously knackered knees to get what was a pretty poor shot anyway. But, on the other hand, if I'd been carrying more weight I would probably given up 3/4 of the way up. Hobsons choice really. Maybe if I'd left that really heavy tobacco tin back at the hostel I'd have got on better lol.
In my case the "wrong equipment" was my bandy legs and clogged up bellows.
