For this trip I took along my 'beater' Leica M2 with the 35/1.4 Summilux, a IIIf with my 'new' 85/1.5 Summarex, and a IIIa with my recently overhauled 50/1.5 Summarit
The light in Barcelona is wonderful - the low winter sun really picks out the detail and makes interesting shadows, albeit that the extreme contrast can make metering a little tricky. My old Weston Master V with Invercone coped very well.
