[Klaus]

I have done longer tests than that in the past.

e.g. the Tamron 200-500mm on APS-C (=800mm equiv):

http://www.opticallimits.com/canon-eos/2...rt--review

However, this was barely manageable.

 

Since this is possible outdoors only, this could be done during winter time at best (on a day without wind).