What are some cool smartphone tricks?

Turn your smartphone into a microscope!*

1. Purchase the shortest focal length lens you can find.  I used Thorlabs-LA1116 with adaptor Thorlabs-LMRA6, gluing the two together with clear nail polish (but any other adhesive will work).
   
   
   ​
   
2. Secure the optic to camera part of the phone, taking care not to obscure the field of view of either one.  Scotch tape around the edge of the small lens holder works fine (I personally use Fashion Tape, an awesome double-stick tape, cut into small rectangles).
   
   
   ​
   
3. Be amazed by the seemingly-mundane things around you!  This setup can resolve features several microns in size, depending of the optics inside your cellphone.  I found that this microscope setup works best when you have image stabilization turned on (because your hand will shake) and the setting which tries to get the entire field of view into focus turned off (the lens has a shallow depth of focus, so you won't be able to get everything in focus if you are looking at a curved object).
   
   
   
   Cashmere
   
   
   Denim
   
   
   LED display, white screen
   
   
   Nail polish
   
   
   Packing foam