Exposure override not working on the 6D

Issue #1908 new
leandroprz created an issue

Just what the title says.

This is how I tested it:

Put the camera in M mode. Let's say it's incredible dark, a moonless night with no light pollution. I set the shutter speed to 4s so I don't have to wait a lot of time for each exposure, I just need to frame my shot. f/2.8 (which doesn't matter since the camera can't read that information because the lens is not chipped) and ISO 25600.

Instead of seeing at least some detail in the screen, I just get a dark image and no visible noise moving around.

On the 60D, which has max ISO 12800, I see much more detail (and noise, of course) than on the 6D.

I tried enabling and disabling exposure simulation. I also reseted my config file to defaults just to make sure other options didn't cause the issue, but it still not working.

Now, if I move the exposure wheel, sometimes there's a brief moment where I see exposure override working, but its just for less than a second and doesn't always happen.

I tested this with magiclantern-v2.3.NEXT.2014Mar12.6D113 This was also discussed here: http://www.magiclantern.fm/forum/index.php?topic=9262.0

If you need more information just let me know.


Comments (27)

  1. Alex

    1) other 6D owners said expo override is working (in the thread you linked, and on the commits linked from there) and now you say it doesn't work at all (how comes?)

    2) remember I don't have a 6D, so you need to show me (video, if possible)

  2. leandroprz reporter

    From what I understand, all the changes you did to the code and posted in that thread are automatically applied to the nightly builds, right? But its not working for me, don't know why.

    The problem is that this feature works under very low light conditions and that will make it hard to shoot, but I will try to make a video.

  3. Mahonri Gibson

    My results, I'm not sure how all these are supposed to behave on other cameras.

    If only exposure override is enabled, it seems to work fine for all av and iso values, but once you set shutter speed any slower than 1/30, the shutter speed stops having any effect.

    If exposure override and exposure sim are enabled, live view gain increases up to about a 10s shutter speed, although it seems a little off (kinda flashes exposure up and down as shutter speed goes slower and slower.

    Exposure sim only - works fine, seems to max out the possible LV gain at about 1", f/2.8, iso400 (or equivalent) after that any changes don't have any effect on the LV

    For leandroprz purposes, it seems that 1% advice to use LV digital gain combined with fps override works fine. (lots of gain, with noise).

    Please let me know if I need to be clearer on anything, I'm willing to do lots of testing.

  4. Alex

    When expo override and exp sim are on, it should apply this digital gain automatically. I should probably tweak the help somehow.

    Transient flashing is OK; it can be improved by redesigning the code around bv_expsim_shift (it first applies raw exposure values without expsim, then it does the expsim calculations and overwrites them). But once you are no longer touching the scrollwheels, it should stop flickering.

    If you enable FPS override, you should be able to go past 10s shutter (since ML EXPSIM is aware of the shutter speed changes done by FPS code).

    "a little off": how much does the LV brightness differ from the final output? You can compare them with the YUV RGB histogram (not the raw one).

    Another tip: ML expsim also tries to sync with the bulb timer value (though at very large exposures it's probably off).

  5. leandroprz reporter

    Thanks for the tip 1%, that did the "trick" I was used to use on my 60D.

    I just checked on the 60D and LV gain is OFF, but I can still see under low light conditions with it because I have exposure override and exposure simulation both to ON. So it seems to be a bug on the 6D, but the weird thing is that other users are not able to reproduce it.

    I also tried FPS override on the 6D but it freezes my LV so it's unusable.

    I made a video showing what I mentioned earlier about the jump on LV brightness for just quick moment on the 6D when changing the shutter speed. Aperture on that camera was f/22 to simulate a low light scenario.

    Here's the video: https://www.dropbox.com/s/0nzyq3nczkge0zl/MVI_2930_1.mov The jump occurs at 00:46 and seems to be random. I had to change the shutter speed several times until it happened.

  6. leandroprz reporter

    I did it like that because it's the only way to reproduce the jump, it happens while changing the shutter speed, not on a specific shutter speed value.

  7. Alex

    Yes, but I'm interested to see both the transient response and the settled value, not just some random flicker.

  8. One Percent

    there might be some jump because the timings change on 6D like 23.97 -> 23.98 -> 23.97, etc. The ADTG shutter lets this happen, if it didn't its back to overheating/hot pixels.

    Its most noticeable at high shutter speeds.

  9. C2S07

    I think manual lenses are a bit problematic. For example, I've been using the Samyang 24mm F/1.4, and even on Canon's original SW, you often don't get accurate LV preview in M-mode, although in Av-mode you do.

    As for ML, which I just now installed on my 6D (build from 2014-03-30). FPS override doesn't really work as expected. When I was using 500D, lowering the FPS would give me a clean and bright LV preview (and of course, low rate of screen updates). On 6D, this happens instead:

    1. I enable FPS override, say, at 2 FPS
    2. The screen updates slow down, as expected. I get a bright preview for a very short time, then it suddenly darkens for some reason.
    3. The rate of screen updates stays slow, but the LV preview is very, very noisy, as if I had simply applied LV display gain. It's also barely any brighter compared to FPS override disabled. Additionally, there's this strange, static overlay of what seems to be an image of noise? Underneath it, the noise that actually constantly updates, can be seen faintly.

    With some combinations of settings, FPS override can also make the screen go crazy. Nothing new here, saw it last on 500D too.

    And exposure override has a LV preview / shutter speed related bug. After you go slower than 1/24, then with each click, the LV preview begins to just alternate between two EVs, like this: normal, darker, normal, darker, etc. At this point, neither of these two accurately simulate the actual exposure, as they stay the same even if you proceed to select very slow shutter speeds.

    I'd like to help sorting these out, if I can. :-)

  10. Alex

    Manual lenses: Canon bug, but expo override is supposed to fix it.

    FPS: sounds like normal behavior for photo mode. ML ExpSim is aware of FPS override brightening the image, so it darkens it back. If you dial a large exposure, FPS should become bright again.

    If you turn off expo override, FPS will brighten the image (but, of course, it will not reflect the still photo exposure).

    "After you go slower than 1/24, then with each click, the LV preview begins to just alternate between two EVs, like this: normal, darker, normal, darker, etc." -> this is a really helpful hint.

  11. C2S07

    Ok. To explain the last one better: when you set a shutter speed slower than 1/24*, eg. 1/20, the preview suddenly looks like you had selected 1/48 instead (rough estimation). You then set 1/15, it looks like 1/24 again. You then set 1/10, now it looks like 1/48 again. 1/8 -> looks like 1/24, 1/6 -> looks like 1/48, and so on.

    • This particular example happened in very dark conditions, so I'm thinking it is experienced when the exposure simulation is working at its limits; sometimes this shutter speed is 1/24, sometimes it isn't.

    "Manual lenses: Canon bug, but expo override is supposed to fix it."

    Yes, it mostly does. Only at some extreme ISO values, I noticed that the exposure of the captured image doesn't always match precisely with the LV preview... but this isn't important now.

    The biggest problem with FPS override right now is the weird, static "noise overlay". Maybe this sounds odd to you, and I wish I had a second camera to make an illustrative video of it (I'll see what I can do), but imagine your LCD screen was covered with (purple colored) dust particles, and the LV preview image is updating beneath it. It can easily get so obtrusive, it's hard to make out the actual LV image.

  12. Mahonri Gibson

    I've had mine do the weird noise overlay thing before, but that was back using an old tragic lantern build. Last time I tested with a new build, I couldn't get it to do it again. I'll have to play with it some more, see if I can recreate.

  13. One Percent

    Well its back because fps agressive update is back in the internals. You have to let the sensor do its thing, if you force it to one value the sensor gets hot and then the hot pixels show up.

  14. One Percent

    I wish I did... the only things that mitigated it were adding the ADTG shutters and turning off agressive update for FPS.

    ADTG shutters should be there as far as I saw but someone added back aggressive update after I had removed it ages ago (since 112).

  15. Morghus

    @C2S07 I had exactly the same behavior when using FPS override. Using the latest nightly from 2014-04-01 it seems to be fixed! Awesome!

  16. One Percent

    Neither method fully fixes it. Even if its all clear at start after the sensor heats up the pixels will start popping up. Also nothing changed with FPS recently.

  17. leandroprz reporter

    Still not working for me. I've been using LV display gain instead, but it's not ideal.

    Maybe some other setting is interfering with this?

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