Sigma Lens Autofocus Problem in Live View Canon 550D

Started Mar 4, 2011 | Discussions thread
carnaga Regular Member • Posts: 301
Temporary workaround

Have you tried to change the Live View AF mode to "Quick Mode"?

When you are using viewfinder, the camera focuses via Phase Detection. And on the contrary, in the Live View mode the camera focuses by default with sensor (Contrast Detection). Changing the Live View Autofocus mode to "Quick Mode" brings you back to the same Phase Detection focusing system as you were (previously) using with the viewfinder.

Another question is that when you are using Live View, you are naturally holding the camera further away from your body to see the LCD. This brings you to situation where you are not having any additional support (comparing to viewfinder shooting where your elbows are in chest, and forehead/eyebrow on cam). The cam becomes more unstable and depending of the situation slightest movement may blur your image (eg. shifts with narrow DOF / camera shake).

Best way to confirm Contrast Based miss focusing is to use tripod and a contrasty flat surface.

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