A few notes on how to use binoculars are perhaps worthwhile. The first step is to adjust the interpupillary or interocular distance, i.e. the separation between the two eyepieces. Fold the binoculars inwards to their closest distance then look through them and slowly open them out until both eyes can see the full field of view, which should appear as a circle. Note the setting on the scale on the central hinge if there is one (marked in millimetres), so that the binoculars can easily be returned to the correct separation for your eyes if they are altered.

 

Next, assuming they are centre focus type, the right eyepiece dioptre needs to be set. Look through the binoculars at a distant object, but not through a window. Close your right eye and adjust the focus with the central wheel until the view through your left eye is properly focussed. Now open your right eye, close your left and rotate the right eyepiece until the view through your right eye is focussed, but without altering the centre focus setting. When you have done this the view with both eyes open should be accurately in focus. Again note the setting of the dioptre adjustment, which is usually marked something like  3 2 1 + 0 - 1 2 3.

 

To find a target through binoculars, look directly at it without binoculars then bring them up to your eyes while keeping your head still, and you should find it is in your field of view.

 

Maintenance

 

Binoculars should need little in the way of maintenance but note:

Do not let them get too hot; this can damage the lens cement.

Do not touch the lenses with your fingers as the oils deposited can etch the lens coating.

Use a soft brush or soft cloth to very gently wipe dust off the lenses, but never rub them. The coating is easily scratched. Camera lens cleaning fluid can be used to remove stubborn deposits but do not let droplets of it dry on the lens or they will leave their own residue.

Binocular focussing mechanisms and hinges do not normally need lubricating but if this is essential then do not use oil as it tends to creep onto the lenses. Use a solid lubricant such as Vaseline instead.