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Using Magic Lantern => General Help Q&A => Topic started by: Armetz on April 23, 2016, 10:38:55 AM

Title: HDR with 1/25 shutter speed at 50 fps?
Post by: Armetz on April 23, 2016, 10:38:55 AM
I want to shoot HDR on a 5D iii using 1/25 shutterspeed at 50 fps which should give me two nearly identical frames with 2 different iso settings. Is it possible to override shutter speed as far in ML? So far I only can get a bit over 360°. I tried 1/25 shutterspeed at 50 fps on a Sony and it worked well but I want Canon, ML, raw and HDR.
Title: Re: HDR with 1/25 shutter speed at 50 fps?
Post by: guru_rb on May 03, 2016, 01:43:48 PM
Could you please let me know at what settings you managed to even touch 360 deg? I have a need to get that but I have not managed to achieve it so far.

Thanks in advance.

Regards,
Guru
Title: Re: HDR with 1/25 shutter speed at 50 fps?
Post by: dmilligan on May 03, 2016, 03:02:21 PM
Quote from: Armetz on April 23, 2016, 10:38:55 AM
1/25 shutterspeed at 50 fps ... with 2 different iso settings.
Explain how it could be physically possible to, in one second, capture 50 different* exposures that each last 1/25 of a second, using only one sensor.

There's some finite amount of time to reset a row (time between when a row is finished reading out and when it is ready to start capturing again) so even an exactly 360° shutter angle is impossible. If you are somehow getting more than 360, then either: there's rounding error on the values displayed (actual shutter speed might be rounded to nearest "common" shutter speed for display, Canon's displayed shutter speeds are usually a bit off, e.g. 30" = 32") or there's a bug in ML's math that computes shutter speed and FPS from the raw timer values. Post a screenshot of the ML FPS Override submenu.

*Your Sony probably just captures 1/50s exposures at 50fps and then merges every frame with the next frame (so frame 1=1+2, 2=2+3, 3=3+4, and so on). This is also something that can be done in post to regular Canon/ML footage (even HDR footage).
Title: Re: HDR with 1/25 shutter speed at 50 fps?
Post by: Armetz on September 16, 2016, 09:58:19 PM
thanks dmilligan for the insights. I didn´t think so far, just read an article on Wikipedia about shutter angles and I think I remember that angles above 360° where described. However, my Sony shoots each 2 frames that are identical exept that their noise differs when 1/25 shutter speed at 50 fps and I thought that´s promising.
screenshots of 5D iii with 360° here: https://www.dropbox.com/sh/7b50wktumr05kl8/AABCrtT2rn3ixgJdXENGUJOna?dl=0