Sony a77 appears to fake video specs!

Started Feb 26, 2013 | Discussions thread
Alphoid
Senior MemberPosts: 2,373
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Still not line skipping
In reply to TrojMacReady, Feb 26, 2013

An optical low-pass filter is the way to battle aliasing. The a77 does not have an OLPF (or it does not have one that would have any effect on a 2MP video; the AA filter is designed for a 24MP image).

A software low-pass filter would not solve moire. A low-pass filter, to reduce moire, has to come before the aliasing. After the aliasing comes into play, high frequency are already translated into low frequencies, and a low-pass filter will not effect low frequencies.

Regarding specific documents:

  • Good software downsampling, as in the F65 will eliminate moire without the need for an OLPF. Bad downsampling will give moire. Both will have identical or near-identical sharpness. 
  • The 5D explanation does not make sense for the a77. The a77 crops, so it is not tied to downsampling for misaligned resolutions. 
  • The D800 explanation, again, leads to moire and not softness. 

The original page has been updated with images with simulated binning and line skipping. In both cases, the output looks much better than the actual a77 output.

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