View Single Post
  #14  
Old 23-04-2019, 03:57 PM
raymo
Registered User

raymo is offline
 
Join Date: Sep 2011
Location: margaret river, western australia
Posts: 6,070
I, just this minute went outside with my wife's 160mm diam. rotating
mirror, full sun and no wind, so focused on a bedsheet hanging on the line.
About 650-700mm f/l and spot approx 6-7mm diam. After approx 1 second
had to pull my hand away as pain too intense, this would set fire to paper
or material pretty damn quickly.
raymo
Reply With Quote