The Diopter: Viewfinder Focus

If you are ever in a situation where your pictures are coming out sharp but you’re looking through your viewfinder and it appears blurry, this might be because your viewfinder may be out of focus itself, this is called the diopter. Not all eyes are created equal. For those without “normal” 20/20 vision, this may be a problem when you look through a camera’s viewfinder—either optical or electronic. Your view into the camera might be blurry even when the camera’s lens is in focus. Because of this, your camera’s viewfinder likely has a diopter adjustment. The option to adjust your viewfinders focus helps you adjust the focus to your own eye, it allows you to customize the viewfinder so that you can see a clear, focused image inside the viewfinder without using eyeglasses or contact lenses to correct your vision.

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How do you know your diopter needs to be adjusted?

The only way to tell if your diopter is accurately adjusted for your eyes is to look around the viewfinder symbology (grid, exposure information, focus points, digital data, etc.) and see if that is in focus. If the numbers, letters, and grid of your viewfinder are tack sharp and the image is not, the camera is out of focus or the autofocus is not working. If both the accurately “focused” image and the symbology are out of focus, you need to adjust your diopter.

How do you adjust your diopter?

Different viewfinders have different adjustments, but there is likely a small wheel or slide near the viewfinder (sometimes labeled with a + and -) that allows you to adjust the view. Rotating this doesn’t affect the focus of your image but just how your eye sees through the viewfinder. There are different techniques for adjusting the diopter, but this is one that should work well:

  1. Mount the camera. If you can, put the camera on a tripod and point it toward a bright scene with sharp straight edges and a fair amount of contrast, something that the camera focus on easily.
  2. Focus the camera. If it is an autofocus camera, activate the autofocus. If you have a manual focus camera, attempt to focus the image (using electronic focus indicators, if available).
  3. Autofocus camera. Are both the viewfinder image and symbology blurry to your eye? Then you need to adjust the diopter. Rotate the wheel until everything is sharp.
  4. Manual focus camera. If the symbology is not sharp, you’ll need to adjust the diopter. Only then can you achieve accurate manual focus (unless you have electronic focus aids). Once the symbology is sharp following a diopter adjustment, adjust the manual focus as needed to ensure you can get the image in focus.

When adjusting a camera diopter (or a diopter on a set of binoculars, for instance) you should adjust the diopter to make the image sharp and keep adjusting until it goes back out of focus. Then, work back toward focus and stop. The reason to turn or slide past the focus is to ensure that you have made the adjustment far enough and not ended up short of true focus. Truth be told, if you are confident in your cameras autofocus, you can likely do a quick and accurate diopter adjustment in the field by just looking at the viewfinder symbology and adjusting the wheel or slide until it is sharp.

Problems

If the camera is out of focus, you see a blurry image in the viewfinder. Then you either focus the camera using autofocus or manual focus and everything is sharp; but is it? What if you didn’t manually focus accurately? Or, worse, what if the autofocus is inoperative or erroneous?

If your camera’s viewfinder gives you sharp viewfinder symbology, but a blurry image, there are likely problems with the camera lens. If the image and symbology are crystal clear, but the image is slightly out of focus, you likely have a minor autofocus error. Verify this by switching to manual focus and see if you can achieve clear manual focus.

Depending on the camera’s diopter adjustment design, the wheel or slide can easily get knocked out of position. So, if you peer into a blurry viewfinder, don’t panic—it might just be your diopter.

If your eyesight is such that a diopter adjustment cannot help you get a clear image in the viewfinder, some cameras can accommodate more extreme adjustment with add-on diopter accessories. Also, some cameras do not include diopter adjustments and the accessories exist to provide the same function as the adjustment dials and slides.

Continue to lesson 36: Understanding the main features of most cameras