Topics

1

General Development / Auto ETTR on EOSM

« on: March 04, 2014, 12:46:37 AM »

Alright since I wanted to use my EOS M as a secondary timelapse camera I wanted to fix ETTR on it and finally dive into ML hacking. Here are a few things I discovered so far:

• auto_ettr_step_lv_slow() and auto_ettr_on_request_task_slow() work, the quick fix would be to use them instead of the *_fast functions, but that's not what I want
• the *_fast functions use CBR_VSYNC_SETPARAM to modify the exposures for each frame
• in auto_ettr_vsync_cbr() the exposure is adjusted for each frame and on my 6D changes are visible immediately, on the M however, exposure is smoothly changed after around 1 second of delay, get_frame_iso() and get_frame_shutter_timer() still return the old value from the previous frame even though set_frame_iso() and set_frame_shutter_timer() have been called
• the *_fast functions expect the exposure to change within 2 frames, it does not happen for some reason and so it over-compensates in each step
• HDR video's hdr_step() uses a similar mechanism to change the exposure for each frame, although not exactly the same because it's not a module, ISO seems to change correctly and immediately for each frame

I'm stuck here... the quick fix would be to use the *_slow functions obviously, but it must be possible to fix auto_ettr_vsync_cbr(). I'd really appreciate it if someone pointed me into the right direction as this is my first time diving into ML code and I have no clue where to start. Is it possible that LV just behaves differently in movie mode? Can I put the camera into this mode if that's true? What other possibilities should I look into?