Author Topic: video_focus.mo  (Read 1452 times)

pparent

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video_focus.mo
« on: December 10, 2017, 04:27:19 PM »
Hi,

After video_av.mo I will do a module to make it easier to focus while video shooting in various situation.

Here are the functionalities that I would want for my module:

1)Make Canon's auto-focus remotely controlled/triggered (useful for selfie video).
2)Display focus value while recording to assist manual focus: a number that corresponds to the focus distances (Useful to note good focus distance in x10 mode and then navigate through them with manual focus, while recording.
3)Display focus indicator (a number) while recording to assist manual focus: a number that tells how well we are in focus, in a certain zone.
4)Have a user-guided follow object auto-focus mode (user specifies direction with keys, the machine goes in that direction as much as necessary to have a good focus).

Do you have any comment on feasibility, or can you help me if you know how to:
1)Trigger canon's AF from code.
2)Get an indication of manual focus state (  a number that corresponds to the focus distance )
3)An indication of how well we are in focus in a certain zone (possibly canon's zone).

Thank's a lot!

a1ex

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Re: video_focus.mo
« Reply #1 on: December 10, 2017, 04:48:40 PM »
1) grep for autofocus in the lua_fix branch, selftest.c and lua_lens.c (not sure if it works well on 500D)
2) lens_info.focus_distance (on lenses that report it; usually very coarse)
    on focus-by-wire lenses, lens_info.focus_pos is also updated in MF (lua_fix branch)
3) try Trap Focus or silent pics in "Best Shots" mode; they use a focus indicator from Canon code
    Magic Zoom's focus confirmation uses the same indicator
    caveat: on models older than 60D, this indicator is not computed for every LV frame
    and unfortunately it won't work at all on 500D: http://builds.magiclantern.fm/features.html - CONFIG_LV_FOCUS_INFO

Difficulty for a fully automatic AF in video mode, compared to fully automatic AE, on a camera without phase sensors (aka focus pixels or pink dots):



(not joking)

There was a feature called Movie AF in very old versions, that also did something similar to your follow focus idea, but I've discontinued it because it was too unreliable and hard to maintain. You may dig through archives and bring it back if you find it useful.

pparent

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Re: video_focus.mo
« Reply #2 on: December 10, 2017, 05:53:50 PM »
Thank's a lot!

I will start working on this as soon as I have time.

I will soon replace my 500D by a 550D (and have the two during a certain period of time).