I was taking some inside pictures with my Nikon D3100 and 18/55 lens when, all of a sudden, the lens started to work funny -- the more I zoomed in on the subject, the fuzzier the picture looked in the viewfinder. I shut the camera down. The next day I tried it again and saw the same effect. Then I got the idea of seeing how a picture would actually look on the LD screen, and just as suddenly, what I saw through the viewfinder was normal. Things were OK again. What happened?

  • 1
    \$\begingroup\$ fuzzier as in "out of focus"? Was the switch Autofocus / manual focus firmly set on Auto focus? Do you know if your lens has an in-body motor for the autofocus or if the motor is in the camera? Have you took some pics in the "fuzzy" version? and how did those turn out when seen on screen? \$\endgroup\$
    – Francesco
    Commented Sep 22, 2012 at 18:43
  • \$\begingroup\$ Sometimes the eyepiece can steam up so be careful ;) \$\endgroup\$
    – Dreamager
    Commented Sep 23, 2012 at 11:09
  • \$\begingroup\$ Was the light level very low when the lens was acting funny? If so, the auto focus probably couldn't lock in properly. \$\endgroup\$ Commented Nov 7, 2012 at 21:22
  • \$\begingroup\$ What do you mean by "fuzzy"? \$\endgroup\$
    – TFuto
    Commented Feb 15, 2016 at 14:18

2 Answers 2


I bet you accidentally adjusted the viewfinder diopter, which lets you compensate for minor or moderate vision problems without glasses or contacts.

On the D3100, it's a little dial above and to the right of the finder window.

Try this to get it set right: How do I calibrate the diopter correction on my DSLR's viewfinder?


My camera did the exact same thing and I found out my switch on my lens was on the M instead of the A I switches it back and all is good! :)

  • \$\begingroup\$ Very basic, but a good first thing to check! \$\endgroup\$
    – mattdm
    Commented May 23, 2015 at 20:57

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