This is the "homemade lens" I use most often for insect macros

Versión en español 

This is the "homemade lens" I use most often for insect macros because it fits in my small pants pocket and I can carry it with me at all times. I removed the lens from 8 x 21 binoculars and mounted it on the plastic eyepiece ring by adding a rubber band through two small holes to attach it to the smartphone. It's not the lens that gives me the most magnification, but it has the depth of field I prefer.

I have also bought lenses like the Apexel ones that attach with a clamp. They have good brightness and magnification, a focal length of 100mm, but their depth of field allows only very small objects to focus properly. In contrast, the lenses I usually use do not magnify significantly, but act as farsighted lenses that allow the smartphone camera to focus from much closer and thus take advantage of the full resolution of the sensor. 

When I go out specifically to take photos I use a silicone case to which I have sewn a rubber band that looks awful but allows me to hold the iphone and shoot using only one hand.

Photos of a ladybug (Coccinella septempunctata) on a fern leaf and an Anthidium manicatum (European carda bee) clinging to a leaf to sleep.
August 3 in Valencia.

My other macro insect photos on Instagram