Hi Giacomo,
Your 8 hour exposure comment brought to mind one of my favourite photographers of the moment Abelardo Morell. He turns hotel rooms into camera obscuras and records the images with a full plate camera using an 8 hour exposure.
Have a look they are fun.
Sounds intriguing - anyone interested should see these.
Cheers, Dave
Thanks for putting up the link Dave. His work is always interesting, often quite challenging. I have learnt most from his work on books...http://www.abelardomorell.net/project/books/ and Alice in wonderland.
Graham