Focusing speed while taking video with OMD E-M10 III

Started 3 months ago | Discussions thread
OP TheEngineer Regular Member • Posts: 386
Re: Focusing speed while taking video with OMD E-M10 III


alcelc wrote:

First all I am a Panny shooter and also a beginner on video.

Might I ask were you on HD or 4K?

The problem unfortunately appears in HD and 4K.

But thanks for the advice, I will do a check again to see if there is maybe a small difference between the resolutions as FHD is good enough for my needs.

On GX85, HD, AF responses very good. On 4K, I also had similar experience as yours.

A reason is because under CDAF (both EM10 and all Pannys use), our camera will seek for a focus from any possible focus point on the entire sensor surface area on every AF attempt. Since video AF is focusing continuously and so could imagine the amount of work the camera will do on repeating the processing.

Therefore, the more candidates having the required contrast inside the focusing area would make our camera harder to follow up, more chances and longer time on focusing would be required.

Under HD video, the amount of data involved is smaller than 4K. Under the limited processing power of GX85 it can handle it well to my satisfaction (reasonably short refocusing time on panning, focus is quite steady on still object etc). On 4K, specially under poor lighting condition (e.g. shooting in a hotel room without extra lighting source), focus hunted and jumped seriously.

However, recently I found a solution: limit the focus area (I use a customized focus zone of 3x3 in the center, as a workable compromise on better AF response). On G85 which allows me to set AF sensitivity (I set it to -1, at a cost of less sensitive to changing focus) has made its 4K video AF usable to me.

I had already tried to reduce the focus area (green box) but will look more into that. I will also look into setting AF sensitivity as I am not sure if that can be done for my camera.

If your EM-10 III supports similar features (customize focus region and AF sensitivity), might worth to see could it help.

Thank you for your response and I hope this can get me closer to a usable focus.

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