Step 1: Being careful not to touch the lens, cover the right objective lens (or close your right eye) and turn the central focusing dial until the image seen by the left eye is clear. Step 2: Cover the left lens (or close the left eye) and this time instead of turning the central focusing wheel, turn the diopter adjustment ring (located near the right eyepiece and displayed on the small image in the upper right) until the image is clear. Step 3: Finally look through the binoculars with both eyes until the image is clear and sharp. 

You can focus clear about 6 ft as far as I know 

The camea can take 1.6v rechargeable batteries, but in general rechargeable battery might drop its voltage quick depend on its physical performance. In the cold weather, recommend using Energize lithium batteries to get longer lifetime. 

You should order one for every manual Nikon lens you want to use with you Sony mirrorless camera. 

Hi, we checked the Sony a6600 18-135mm lens seems 55mm, if you like this filter, please reconfirm the lens size, the 55mm lens need to order 55mm size filter,thanks.