Diagnosing Photo Quality Problems with a Canon EOS Rebel T3 Series Camera

By Julie Adair King

Getting the maximum output from your Canon Rebel T3 or T3i depends on choosing the right capture settings. Chief among them is the appropriately named Quality setting. This critical control determines two important aspects of your pictures: resolution, or pixel count; and file format, which refers to the type of computer file the camera uses to store your picture data.

Resolution and file format both play a large role in the quality of your photos, so selecting from the Quality settings on your camera is an important decision. Why not just dial in the setting that produces the maximum quality level and be done with it? Well, that’s the right choice for some photographers. But because choosing that maximum setting has some disadvantages, you may find that stepping down a notch or two on the quality scale is a better option, at least for some pictures.

The term picture quality refers to how finely the image is rendered in the digital sense.

Refer to this symptom guide to determine the cause of poor image quality.
Refer to this symptom guide to determine the cause of poor image quality.
  • Pixelation: When an image doesn’t have enough pixels (the colored tiles used to create digital images), details aren’t clear, and curved and diagonal lines appear jagged. The fix is to increase image resolution, which you do via the Quality setting.

  • JPEG artifacts: The “parquet tile” texture and random color defects that mar images can occur in photos captured in the JPEG (JAY-peg) file format, which is why these flaws are referred to as JPEG artifacts. This defect is also related to the Quality setting.

  • Noise: This defect gives your image a speckled look. Noise is most often caused by a high ISO setting (an exposure control) or by long exposure times (shutter speeds longer than one second).

  • Color cast: If your colors are seriously out of whack, try adjusting the camera’s White Balance setting.

  • Lens/sensor dirt: A dirty lens is the first possible cause of the kind of defects you see in the last photo example. If cleaning your lens doesn’t solve the problem, dust or dirt may have made its way onto the camera’s image sensor.

    The Canon Rebel T3i offers an automated, internal sensor-cleaning mechanism. But if you have a T3 and/or frequently change lenses in a dirty environment, a manual sensor cleaning is necessary. Find a local camera store that offers this service.