Headline - DSLRs have imprecise focusing due to their mirrors

Started 6 months ago | Discussions thread
Greg A A
Contributing MemberPosts: 895
Re: In practice...true.
In reply to Lab D, 6 months ago

Lab D wrote:

Lee Jay wrote:

conceptually, the optical paths cab be different lengths leading to consistently missed focus, and single-shot focus can be open loop.

In practice, I use closed-loop AI-servo and all of my cameras and lenses are calibrated right out of the box meaning I get 99% or so in-focus shots in the most difficult conditions. My contrast-detection cameras can't come close to matching that even with much more depth-of-field and much easier conditions.
Lee Jay


1. Phase-detection autofocus (even using still targets and center-point only) wasn’t nearly as accurate as contrast detection.

2. The contrast-detection autofocus was about as accurate as the most careful manual focusing.

There have been many tests by unbiased sources showing Contrast Detect is usually more accurate.

For those who missed it here is a test that contradicts the test results you posted.

"The contrast detect results on the 5Dmk2 and 7D show a big focus error with a reasonable amount of variability between the shots too. This just translates to out of focus shots – plain and simple" - from:http://www.reikan.co.uk/focalweb/index.php/2012/12/af-consistency-comparison-nikon-canon-phase-detect-contrast-detect/

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f8 and be there

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