Images not sharp

 

There are many factors for images not being sharp and exhibiting in many ways.

 

Camera

 

Dust on the mirror or A/F sensor

Wrong custom settings

Using the wrong focus bracket

User movement

Low light shooting conditions

Focus screen, mirror, bayonet mount or sensor out of alignment

Worn mirror box causing shutter bounce

Tough subject for the auto focus to lock on to

Camera needs to have a focal calibration

Incorrect fine tune set up

The eyesight diopter is incorrect for your eyesight making it look blurry though the eyepiece

You are too close to the subject

 

Also see lens focus issues