in the custom settings of the F5 you can set it to do exposures in shutter mode out to 30 minutes. I've done it, albeit with not very good luck, more just to see if I could do it
With lithium batt's in my FE and FE-2, I've gone for an hour or more.
I tested all my aperture priority auto expose capable cameras (Canon, Minolta, Nikon, Olympus, Pentax & Ricoh) and found only the LX to be capable of hours long auto exposure. Also, unlike the others - with the exception of the OM's, it constantly monitors the scene for changes in lighting and will adjust accordingly + or -.
Regarding adjusting for reciprocity, I am certain most all film makers only account for up to minutes long.
Haters gonna. C41 is your friend for exposures like that, the latitude helps compensate for reciprocity failure. The half-hour exposures I made with my F3 were on Reala; don't know if it's particularly good at long exposures or what, but the negs turned out okay.
Man, I am bummed to find YET ANOTHER reason I shouldn't have sold that camera...
You don't get many 30 minute exposures on "A" before the camera batteries are flat, it's much better top make a time exposure.
This is not the case with both of my Pentax LX bodies as they time reasonable similar even though the manual does state only 125 seconds at f1.2.