While looking online at some designs I came upon a solar furnace plan using a similar lens, The lens for the furnace was 11 x 11 mine is 7 x 10.
Well yesterday was a sunny day so I took the lens outside and did th school boy trick of focusing the sun on the wood.
I was blown away the wood ignited instantaneously! It took less than a second to burn.
I recall reading a Mother Earth News where an artisan did incredible woodburnings using the sun and a couple of condenser lenses. There was a picture in the magazine of a wall mural done this way.
I am not sure how good a job someone could do with this type of lens but it may be worth doing some experimenting.
By the way the solar furnace was capable of heating to 2000 degrees! be careful. Spend a dollar have some fun and have a flashback to school days.
