Adjusting the Viewfinder to Your Eyesight

viewfinder diopter adjustment switch
The viewfind­er diopter adjust­ment is typ­i­cal­ly a wheel or switch locat­ed on or about the viewfind­er on most cam­eras. This is the diopter’s posi­tion on a Canon EOS 7D.

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

  1. Locate the diopter adjust­ment con­trol. This is typ­i­cal­ly a small cir­cu­lar dial or lin­ear switch near the viewfinder.
  2. Turn on your cam­era and remove the lens cap (if one is on).
  3. 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. 
  4. Com­plete­ly relax and defo­cus your eyes, and half-press the shut­ter but­ton to acti­vate the data dis­play with­in the viewfinder.
  5. 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.