Look at what I learned to do! So much fun and really easy to do. Go here to read how...
he diameter of a 50 mm lens at an f-stop of 2.0 is 25 mm wide. A 100 mm lens at an f-stop of 2.0 is 50 mm wide. It was not exact math at all but it turned out pretty fun. I used really thick water color white paper, worked just fine. Cardstock would work too I think. I folded the paper in half to cut out my heart.
I tried all sorts of focusing to get different size hearts. Fun photography trick and easy enough for me to give it a whirl!
Now my Christmas tree looks more fun!