I use external optics: lens Helios 44M-5 (58mm, f2.0) from old film SLR camera Zenit made in USSR. These lens reverse mounted, and Canon Powershot A650's built-in lens looks straight to frontal Helios lens. I shoot in maximum optical zoom mode (6x) instead of macro. Built-in lens in this mode have 200mm equivalent focal length. I wrote small post about snowflake shooting technique in journal: [link]