Old Locks vs New Locks
Locks are difficult to take pictures of I have found. The old ones, if well maintained, are all about tranquility, serenity, and the interesting juxtaposition between the masonry and the green strip of grass (or - mostly - stagnant water) that constitutes the floor between the old stone walls. The newer, active ones, have a completely different set of rules to them, photographically speaking. You deal with boats and their shapes, people moving about, the waters swirling once the gates close, and all that; it requires a different approach to the imagery.
Good luck with the challenge.
I went out this morning to shoot some images for the "lock" challenge. Being near the Erie canal I knew of a few old lock ruins that were close PLUS they are close to the current active canal. When I got back and processed the images I actually liked the non cropped images of the old canal better than the new one canal.
These old canals are over a 100 years old and the doors have long since been scrapped or fallen off so all that is left is the old granite sides. I caved to conventional wisdom and entered the "new" lock door instead of the beautiful old carved rock sides.
The color uncropped image is nice with fall leaves but the challenge rules were B & W and 1600 X 1600.
Images along the way: http://hahn.zenfolio.com/serendipity