About 4m/13ft. 

First adjust the focus, then aim the lens at the target, observe through the glasses and adjust the focus until it is clear. 

Dear Customer, Thank you for your question. Please check the following steps to setting the focus: (Do not look at too close objects) Step 1. Cover the right objective lens with your hand or close your right eye, rotate the central independent focusing wheel until the image in the left eyepiece is sharp and clear. Step 2. Now cover the left objective lens or close your left eye, rotate the right eyepiece focusing wheel to adjust the diopter of the right eye until the captured image is sharp. 

This monocular is very useful to look faraway. My kids love it very much and use it to watch the airplane and the seagulls flying through the sky.  

Yes. The monocular can be attached to most standard tripods, table tripods and monopods with the universal 1/4" screw.