Diopter adjustments: adjusting the viewfinder to your eyesight
The majority of cameras with optical and electronic viewfinders allow you to make adjustments to the viewfinder’s focus to match your vision. Known as diopter adjustment, it’s a critical step in ensuring that your view through the finder is clear and not blurry.1Diopters correct for minor near- and far-sightedness; they don’t compensate for astigmatism.
Diopter adjustments are especially useful if you wear corrective glasses. Looking through a camera’s viewfinder while wearing glasses is awkward. Glasses impede the rubber cup of the eyepiece from completely shrouding your eye to outside light, and any oils that collect on the eyepiece can smudge your lenses. Adjust your viewfinder’s focus to match your uncorrected vision for a much more pleasant and hassle-free experience.
How to correctly set the diopter adjustment
- Locate the diopter adjustment control. This is typically a small circular dial or linear switch near the viewfinder.
- Turn on your camera and remove the lens cap (if one is on).
- With a finger on the diopter adjustment control, look through the viewfinder and point the camera towards a bright, featureless subject, such as a light wall or ceiling, or the blue or overcast sky.
- Completely relax and defocus your eyes, and half-press the shutter button to activate the data display within the viewfinder.
- Adjust the diopter control back and forth until the data displayed in the viewfinder come into sharp focus (i.e., the numbers along the bottom edge, focus markers, gridlines, etc.; not the scene in front of your camera).
Diopter adjustments and eye strain
The complete relaxation of your eyes in step 4 is critical to this process. Setting your viewfinder focus in such a manner will minimize eye strain and fatigue, especially after prolonged periods of using the camera.
Diopter adjustments and lens focus
Adjusting the viewfinder to match your eyesight does not affect how your camera lens focuses on the scene. However, by bringing the viewfinder into sharp focus, you increase your ability to identify autofocus errors before taking the picture by seeing the most acute possible rendition of the scene in the finder.