I got a few box cameras with "held-down" B setting, a homemade wooden cradle+elastics for tripod mount, typical Ilford film, and a few sites suitable landscape dawn or dusk situations.
I am looking for a few tips on how to best proceed with issues like smooth shutter operation, maybe exposure control via filters, avoiding hitting a reciprocity boundary, and other potential issues.
Multiple exposures techniques would be the next step, or combined as well.
While I haven't done a lot of long exposures with my box cameras, I have done many with a Holga - which is effectively very similar.
Like already stated, on long exposures into the minutes, I wouldn't worry much about any initial bump/shake when you press the shutter, but you want it to be still for most of it. Not certain which box camera you are using, but you will want to find a way to mechanically hold the shutter open other than your finger. Tape, rubber band, toothpick jammed in there - whatever works would be fine. For my Holga I have a add-on cable release that's really nice, but on the occasion where I forget to pack it, I've used a rubber band.
Filters - on bright days these will be key to a long exposure. You can glue/adhere a threaded filter ring so that you can use filters - 52mm is ideal due to commonality and cheap prices. Or if you are just wanting to try it out first, just holding the ND filter in front of the small lens opening on the box camera works as well. I've done that in a pinch with the Holga before finding a slip-on 52mm filter thread.
I've never shot anything longer than an hour exposure with the Holgas, and that has been fairly easy in terms of sticking to the reciprocity failure times listed and following them.
Sounds like fun, can't wait to see the results!
Jeremy
Below is a 4 minute long exposure on a Holga and Ilford Delta 100.
