Smartphones can be used to image the moon by holding it next to the eyepiece of a telescope. For smart phone cameras, a mid-power eyepiece such as a 25 mm eyepiece yields good results. This imaging method is called afocal imaging, in which a camera with its lens is mounted next to another image-forming optical system such as a telescope or a pair of binoculars. To hold the phone camera steady while taking a photo, a smart phone-to-telescope adapter may be used. The adapter below was built using a mobile phone holder attached onto the side of a 90 degree diagonal mirror (star diagonal).
Another version of a smartphone-to-telescope may be built using inexpensive materials using a piece of plywood, hose clamp, screw, and rubber bands. Secure the hose clamp onto the plywood using screws. Use the hose clamp to hold the eyepiece in place. Use rubber bands to hold the smart phone camera and adjust as necessary.
Related link: Universal Camera Adapter
Night Sky in Focus © Anthony Urbano | Bacoor, Philippines