Aliasing on Straight Vertical lines with 4k video on A7r3

Started Oct 16, 2018 | Discussions thread
Beaverhelmet Senior Member • Posts: 2,296
Re: Aliasing on Straight Vertical lines with 4k video on A7r3

Chester McCheeserton wrote:

I'm wondering if anybody has any suggestions or tips for getting rid of whats happening in the straight vertical lines you can see in the green building in this clip. Not trying to fix this clip but trying to prevent it in the future.

This was shot on an a7r3 in 4k in super 35 mode on a Zhiyun Crane 2. The footage was downsized to instagram sized here, I initially thought it was the thing you see in stills in photoshop when zoomed out that disappears when zoomed in to 100%, but alas I seem to have a problem. shutter speed was 1/50th of sec, frame rate 24 p 100m, Picture Profile set to PP5.

Thank you!

As Mike said, this is a moire issue. Your question is unclear though. If you want to avoid moire in the original 4K footage, use an aperture value that puts the problem areas slightly outside of the focus area. A really small aperture, provoking a small amount of diffraction can also help. In some rare cases even a soft filter is used (common in cinematography).

If you want to address moire when downsampling in post, the result can vary a lot depending on compression settings and software used. This is mainly a computational issue.

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