Thanks Victor, I have tried an heavy manfrotto tripod fixing the lens barrel with a magic arm. It seems I'm getting sharper shots, even if I wait about 30s for the camera to calm down, then 2s delay timer with mirror up.
I will test again with slow and fast shutter speeds.
Thanks to Tho_mas too, I have no wood tripod here but I will try first to heavy load the aluminum one I have first.
Kind regards
Roberto