Which dial on the 10X40B is diopter correction?

Some cameras have a small dial near the viewfinder to correct for your vision or if you wear glasses. Look for that.

1. Remove the lens covers, if they are in place.
2. Set the diopter on the right barrel eyepiece. The function of this setting is to adjust between vision differences between your eyes if you are NOT wearing corrective lenses. Set to zero if you do have corrective lenses on (glasses or contacts). For proper diopter adjustment see this article: Binocular Selection Guide.
3. Most binoculars will hinge in the middle to allow for differences in the spacing between the eyes. Set the spacing to fit your eyes.
4. Adjust eye cups. Each eyepiece will have a means of maintaining the correct eye relief for the user. On quality binoculars the rim of the eyepiece will extend and retract as you twist the eyepiece rim. Move all the way in if you are wearing eyeglasses or adjust out if not wearing eyeglasses. You will know if they are set correctly when you look through the binoculars and check to be sure that the circular edge of the view should be sharp and not fuzzy. At this point we are not looking at any object in the view but rather the perimeter of the view. You may need to adjust the eye cups again to compensate. On lower cost binoculars the eyecup may only be a rubber lip that you either fold over (the "in" position) or out.
5 Raise binoculars to your eyes and use one finger to adjust the focus wheel on the center shaft between the two barrels, until the view is in sharp focus. If viewing for extended periods you may want to keep your elbows down near your side as this will increase comfort while viewing.
Final safety tip: Do not look at the sun through binoculars.

Many people enjoy observing nature with binoculars. Having them handy is key. Hunting, astronomy, marine use, and stadium sports are a few more activities where having a pair of binoculars can make a real impact to your experience.

Diopter is for your eye only and does not effect the focus of the camera. By using the 1/2 down method, by pressing the photo taking button half way down, you can set the cameras focus. on some cameras this is shown where it will focus by a red square. If you change the diopter this is like adding by focal lenses for reading a book. and setting the distance your particular eye needs for eye relief. On binoculars this is done with screwing the eyepiece closer or farther away from the other lens. check out online http://en.wikipedia.org/wiki/Eyeglass_prescription this will give you more details of what a diopter is or does. Always know what setting your shooting at as well. for instance if you are on a flower setting or Macro then this is for up close work. But up close doesn't mean too close. Most cameras on Macro need to be 6 inches to 12 inches away. But if you are say 24 inches away it won't focus right so don't try to zoom in, use your optical instead of digital and simply move closer or change the settings on the camera to a different setting or it may be blurry.

possible that the set screws are loose and not turning the eyepiece inside..other than that try cleang the lenses...larry@reichinstruments

Try adjusting the viewfinder diopter. There's a little dial just to the right of the viewfinder. Turn it while looking through the viewfinder. You want to be looking at an unfocused view or a blank wall. Turn the dial until the focus brackets are sharp. Make sure you do this with your shooting eye.

It is common for binoculars to have one independently focusable eyepiece.  If one eyepiece can be rotated, then that is the case.
If that is the case, focus through the one that DOES NOT rotate using the center control until you get a sharp image on that side.  Then rotate the eyepiece on the blurry side until the blurry side is sharp.  If you succeed at this, from henceforth the center control will focus both eyes adequately

The entire diopter setting eyepiece was off.I separated the eye cup from the rest of the diopter setting eyepiece, and aligned the channel guides on the lens piece to slide it into place. Then holding it in place, taking care not to gum up the lens, I experimented with how to screw in the retainer ring so that its white dot registered correctly. Finally reattach the eye cup and focus. It's like new!

1. The viewfinder's diopter is probably out of focus (doesn't affect Auto Focus of photos). There's a dial and a +/- symbol next to the viewfinder. Turn the dial till you can see clearly through it. Alternative reason: The glass in the viewfinder is dirty/foggy. Use camera cleaning solution (a drop) on a cotton bud to clean it.

2. Malfunction needs Canon Service Centre to take a look at.

Your binoculars are known as the Zeiss Classic or what was once known as the Dialyt. They focus differently from the usual binoculars like those mentioned. The rear wheel is to focus both binocular barrels while using them. The front focus wheel is adjust the right eyepiece to suit your right eye. Binocular manufacturers take into account each eye is slightly different. To focus the Dialyt...First close your right eye and turn the rear wheel until the image is sharp in the left barrel. Leave the focus wheel alone. Now close left eye and adjust the front wheel until the image is sharp for your right eye. The image should now be clear and in focus for both eyes. It should not be needed to use the front wheel from now on. The rear wheel is what you will use to change the focus from near to far objects.

It sounds like the eyepiece focus adjustment knob may just need to be set for your eyesight. There should be a small knob or dial with a + & - sign around it. This is the "diopter" which doesn't affect the camera's focusing, only how you see the image.