The Diopter

Have you ever looked through the eyepiece of your DSLR camera and thought things just weren’t quite in focus?  Perhaps you wear glasses and find they get in the way, but you need them to frame your shot properly?

Most brands of DLSRs (and some point and shoot cameras) have a dial or slide of some type to the right of the eyepiece.  Nikon’s can be big or small and obvious; Canon’s is more discrete (especially with the eyepiece cup mounted).  They work the same on both systems.  The diopter adjustment knob works as a lens switching from near to far focus.  It does not affect the focus circuitry of the camera as it is after the auto-focus mechanism.  It only affects how your eye picks up the image.

It works just like the device an optometrist puts in front of you when checking your vision.  That device has lenses of various concave and convex curves to adjust for near sightedness and far sightedness.  They adjust for an eye that can’t focus at a reasonable distance, such as for close objects like reading this text.  That little dial on your camera typically has an adjustment range of -3 to +3, with 0 being nominal 20/20 vision, more or less.

If your eyesight is anything less than average (essentially what 20/20 is telling you), this knob will be your best friend to help shoot better photos, especially if you attempt to use manual focus.  To set the diopter correctly, you will need to set your camera on something solid, like a tripod, and point it at something flat with enough texture to be easily seen.  Press your shutter release halfway down to focus your camera with auto-focus.

All things being equal this test relies on the idea that your camera focuses properly, obviously.  Without moving the camera, turn the diopter control until (with or without glasses) the image is in focus to your eye.  Really that is all there is to it!
I know it sounds simple, but sometimes even a small adjustment for those who think they have average eye sight can be helpful.  Happy shooting!