Alternating Shutters frame to frame in video

[SB]

Is it possible to program the mark II to have variable exposure (shutter and/or aperture) from frame to frame while recording a video. For example, could I enable video to have the first frame have low exposure and the next frame have high exposure and then continue alternating frame to frame. I realize that HDR video exists in terms of alternating ISO, but this isn't suited for my needs. I would need programmable shutter times and aperture size. Thanks!

[Malcolm Debono]

Why isn't it suited for your needs?

If this was possible (which I think it isn't), I would think that it might easily damage the lens (changing the aperture 12 times per second...).

[Bubel]

I think it`s for imitating old hand cranked camera, I thought about this function too because I love how hand cranked footage looks like.

[SB]

Sorry for taking so long to respond.

I am part of a university research group trying to develop an algorithm to produce HDR video for dynamic scenes. The group has successfully produced HDR images for dynamic scenes without any artifacts. The next step is to expand our algorithm to the temporal domain and produce HDR video. To do this we would need a camera that records frames with alternating exposures. If we alternate between 4 exposures then we believe our algorithm will combine them without the artifacts that plague most state-of-the-art HDR video methods. However, finding alternating exposures from frame to frame is proving difficult...

Any suggestions would be greatly appreciated.

Thanks!

[g3gg0]

yes, its possible if i remember correctly.
in early versions both ISO and exposure was implemented.

can you tell us some more details about what you exactly need?
and maybe some more details about your project?

[SB]

@g3ggo

Thank you for your reply.

We are a research group at the University of California, Santa Barbara. The group has already implemented an algorithm for HDR Imaging for dynamic scenes. Please see site below for more information
http://www.ece.ucsb.edu/~psen/hdr
We are preparing for a SIGGRAPH 2013 submission that applies these concepts to HDR Video.

Specifically, we need to be able to program the shutter time and/or aperture so that they are different on a PER-FRAME basis. This would be set before video capture and not during. The sequences we plan to capture would be short (~15 seconds). We would like to alternate between three to four exposures. For example, the first frame could be captured with a shutter time of 1/30 then the next frame could be 1/60, then 1/125, and 1/250. The process would then repeat. This would allow us to capture high dynamic range content in non-static scenes. Then we could apply our algorithm to produce artifact free HDR Video. If this could be extracted as RAW data that would be even more beneficial because with more bits we could have more stops between exposures.

Hope this clarifies things. Please let me know if you have any questions.

Thanks!

[g3gg0]

thanks for this information.
i will look into it in 1-2 days.

[SB]

thanks for this information.
i will look into it in 1-2 days.

Thank you!

[g3gg0]

first prototype is working.
it allows free ISO configuration for up to 8 frames. but exposure time is not working yet.

[SB]

first prototype is working.
it allows free ISO configuration for up to 8 frames. but exposure time is not working yet.

Thanks for looking into that for me. I would appreciate it if you could let me know when the feature works for exposure time.

[a1ex]

It's already working, you need to compile ML yourself.

http://bitbucket.org/hudson/magic-lantern/commits/0e834279be06e17d5a594098ce42ec618da3bed0

Shutter speed can't be changed on 5D Mark II, only on 60D and newer cameras.

In HDR mode, shutter speed can go as far as 1/25000 (tested on 5D Mark III).

Edit: if you need variable aperture, you can try to set it with exposure override, but you don't have precise control over timing (because aperture is a slow mechanical device). You can read the value of FRAME_APERTURE to see when the aperture was actually changed, maybe it's still useful.