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Thread: Canon 5D Exposure Lock Question

  1. #1

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    Canon 5D Exposure Lock Question

    Dear Folks:

    I am trying to learn HDR photograph and have a question regarding exposure lock on my Canon 5D. One very knowledgeable photographer stated that she will first meter a mid tone range in her photo then press the exposure lock, and next compose her shot. I have tried this and it works. But when I make my second adjustment, the exposure lock is no longer in effect.
    My setup is that I combine auto exposure bracketing with exposure compensation to get a larger range. From -2, 0, +2 with 3 shots to -4, -2, 0, 0, +2, +4 with 6 shots. I have to do this in two sequences. So this is what I want to do: Set AEB for its largest range (+/-2), meter for mid tone and press the exposure lock, recompose my scene, set exposure compensation to the very "left" and this first sequence will take a range of -4, -2 and 0. Now I have to change the exposure compensation to all the way to the "right." So now I have 0, +2, +4. When complete, I can just delete one of the "0" shots. I should add that my camera is in aperture priority mode.

    How can I get my exposure lock to remain in effect for my 2nd sequence of shots? As always, I appreciate all responses.


    Dave
    Last edited by acroreef; 10th June 2012 at 05:33 AM.

  2. #2

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    Re: Canon 5D Exposure Lock Question

    I don't own Canon cameras but it is my understanding that this is a limitation in the exposure controls.

    Normally with a Canon, you must press the AE Lock button within two seconds of taking a picture if you want to reuse the lock for the next picture. I'm unsure how this works with bracketing, so you'll have to experiment. The Canon 1D series has a post-capture timer that allows you to control this particular time-out, and you can set it as long as 30 minutes.

    With Sony DSLRs, once you lock exposure it remains until you unlock. With Nikon DLSRs, there's a single meter timer that can be extended to 30 minutes on some bodies, and indefinitely on others. The camera holds the lock for as long as the meter is active. I find it quite amazing how much cameras differ in the way they handle advanced AE functions such as AE Lock and EC.

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    Snarkbyte's Avatar
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    Re: Canon 5D Exposure Lock Question

    Why not just shoot in manual mode? Use the same sequence, but reset the exposure instead of EC. I don't understand the motive for Av here.

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    William W's Avatar
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    Re: Canon 5D Exposure Lock Question

    Quote Originally Posted by acroreef View Post
    I am trying to learn HDR photograph and have a question regarding exposure lock on my Canon 5D. One very knowledgeable photographer stated that she will first meter a mid tone range in her photo then press the exposure lock, and next compose her shot. I have tried this and it works. But when I make my second adjustment, the exposure lock is no longer in effect.
    My setup is that I combine auto exposure bracketing with exposure compensation to get a larger range. From -2, 0, +2 with 3 shots to -4, -2, 0, 0, +2, +4 with 6 shots. I have to do this in two sequences. So this is what I want to do: Set AEB for its largest range (+/-2), meter for mid tone and press the exposure lock, recompose my scene, set exposure compensation to the very "left" and this first sequence will take a range of -4, -2 and 0. Now I have to change the exposure compensation to all the way to the "right." So now I have 0, +2, +4. When complete, I can just delete one of the "0" shots. I should add that my camera is in aperture priority mode.

    How can I get my exposure lock to remain in effect for my 2nd sequence of shots? As always, I appreciate all responses.

    For this job, I wouldn't use AEB and I wouldn't use Av Camera Mode, and certainly I would not combine AEB with EC: that is far too complicated, cumbersome and time consuming.

    For HDRI, its assumed your Camera is solid on a tripod.
    You would first make your indicative Exposure Reading and from that reading make the Bracket required by using Manual Camera Mode and manually changing the Tv. (Shutter Speed)

    As an example for this case, let's assume the indicative exposure (i.e. the 'zero' on the Bracket) is = F/8 @ 1/200s @ ISO400

    Then the Bracket of five shots (-4 -2 0 +2 +4) is made by initially shooting the first frame = F/8 @ 1/3200s @ ISO400. And then the subsequent frames at the following Shutter Speeds, each changed manually:

    1/800s; 1/200s; 1/50s; 1/12s.

    It is understood that you may want to use AEB to employ the Burst Rate of the 5D to minimize the possibility of Ghosting or other affectations but the point is you are snookered with a 5D for HDRI anyway, as it can only Bracket 3 Shots and the maximum increment is 2EV.

    So on the list cameras to use AEB for HDRI - the 5D is not the best performer: hence the opinion that may as well use a manual shutter speed change, to attain the EV compass and the number of Shots required in the bracket.

    As I understand there is not any Canon EOS camera which will give you 4EV range in an AEB: but the 1 Series and the 5DMkIII will give you provision for a 7 shot bracket, but with only 3 EV range.

    WW

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    Re: Canon 5D Exposure Lock Question

    Quote Originally Posted by William W View Post
    For this job, I wouldn't use AEB and I wouldn't use Av Camera Mode, and certainly I would not combine AEB with EC: that is far too complicated, cumbersome and time consuming.
    Actually, it's less complicated, less cumbersome, and less time consuming. That's why the OP wants to do it.

    You have to consider the sequence of events. First, exposure is locked by simply metering a mid-tone and pressing a button. Then EC is set to -2. So far, the shooter has one button press and six clicks of a dial invested in the process. The shutter is pressed and click, click, click. AE Lock is pressed again, and EC is set to +2, which is 12 clicks in the other direction. Another shutter press and you're done. So the investment in actual camera manipulation should be two button presses for AE Lock and one dial turned twice. Also, the shooter is able to use the viewfinder Exposure Display to set the EC values graphically, so no counting of clicks or tracking of shutter speeds is necessary. It's a very fast process, but it requires understanding how the camera works.

    Your way, shutter has to first be manipulated to give the desired exposure, then from that point the shutter has to be adjusted 4 stops in each direction. The 5D meter only shows 3 stops, so you have to keep track of where you are by watching shutter speeds or counting clicks of the dial. You have to go 4 stop in one direction, and then 8 stops in the other direction, taking a picture every two stops.

    Having to track shutter speed...being off the Exposure Display...pressing the shutter 5 times...that is way more cumbersome than then Av/EC/AEB process described above.

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    William W's Avatar
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    Re: Canon 5D Exposure Lock Question

    double post

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    William W's Avatar
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    Re: Canon 5D Exposure Lock Question

    Quote Originally Posted by Graystar View Post
    shutter has to first be manipulated to give the desired exposure, then from that point the shutter has to be adjusted 4 stops in each direction. The 5D meter only shows 3 stops, so you have to keep track of where you are by watching shutter speeds or counting clicks of the dial. You have to go 4 stop in one direction, and then 8 stops in the other direction, taking a picture every two stops.
    That is NOT the methodology which was described in post #4:
    This is the methodology as described:

    "As an example for this case, let's assume the indicative exposure (i.e. the 'zero' on the Bracket) is = F/8 @ 1/200s @ ISO400.
    Then the Bracket of five shots (-4 -2 0 +2 +4) is made by initially shooting the first frame = F/8 @ 1/3200s @ ISO400. And then the subsequent frames at the following Shutter Speeds, each changed manually: 1/800s;
    1/200s; 1/50s; 1/12s."


    Firstly: the shutter does NOT have to first be set to give the desired exposure i.e. the shutter does NOT have to be first set to the '0" of the Bracket (F/8 @ 1/200s @ISO100).
    Even if using the camera's TTL meter is used to make the initial Lightmeter Reading; the LED in the Camera's Viewfinder does NOT have to be set to the middle position to make an accurate meter reading.

    Secondly: when shooting the bracket, the Tv does not have to be manipulated 4 stops either way; the first shot taken begins the bracket at -4EV, i.e. the first shot of the bracket is taken at: F/8 @ 1/3200s @ ISO100.

    Thirdly: the fact that the Viewfinder only reads 3 Stops is totally irrelevant.
    The Tv is manually changed from the first shot - at 1/3200s.
    Clicks MAY be counted, yes: but, it is easier (my opinion) to read Shutter Speed in the display on the top right of the camera to make the shots at the next FOUR Tv settings.

    Best practice dictates the Viewfinder will be covered by the Eyepiece Cover anyway, so the Photographer would not be looking through it.

    ***
    Quote Originally Posted by Graystar View Post
    Actually, it's less complicated, less cumbersome, and less time consuming. That's why the OP wants to do it.
    It is an opinion (my opinion) that this manual methodology is less complicated, less cumbersome, and less time consuming than using AEB and EC to make a bracket of FIVE shots with a compass of 4 EV at 2EV intervals.
    Others’ opinions might differ as to which method is easier and to have differing opinions on what is easier is fine: but when comparing methods it is very important to use the method ‘as described’ to compare it to another method.

    I have no idea why the OP wants to use AEB and EC.
    If others do know as a fact that the OP is using AEB and EC because the OP believes it is an easier method to make this bracket: then they have either a crystal ball or are privy to knowledge which is not yet disclosed on the thread.
    But, I doubt (another opinion) that the OP knows yet, what is the easier method for themselves to use to make this bracket for HDRI; and this is indicated by the two phrases: “I am trying to learn HDR photograph” and “As always, I appreciate all responses.


    WW

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    Re: Canon 5D Exposure Lock Question

    Hi folks,
    Thanks for all of the helpful suggestions. I wanted to limit the number of times I would have to touch the camera to limit movement, even though the camera will be on a sturdy tripod. Also, Using AEB and exposure compensation together, I would have two "bursts" of three shots each, resulting in a -4, -2, 0, 0, +2, +4. I believe the quicker this can be accomplished, the less chance of problems with scene movement, such as clouds, etc. But since my exposure lock will not remain in place for more than 4 seconds (unless I am mistaken), this may not be the solution I was hoping for. Again, thanks to all.

    Dave

  9. #9
    inkista's Avatar
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    Re: Canon 5D Exposure Lock Question

    Which 5D are you using? Because if it's the MkII, maybe waiting for the Magic Lantern Unified build that includes the 5D2 could get you what you need.

    On my 50D with ML, I can bracket 3-9 shots at 0.5EV-5EV intervals. One shutter button press to take the set. It's kinda cool. But. It's Magic Lantern, so all the usual caveats about messing with non-manufacturer firmware add-ons apply. For me, it was worth messing with because the 5D2 is my main camera , and I use adapted manual focus lenses, so having focus peaking was a big plus. And on top of that, my 50D can now shoot video. It's a little beta-ish wonky on the 50D, but I've been enjoying it.

  10. #10

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    Re: Canon 5D Exposure Lock Question

    Quote Originally Posted by acroreef View Post
    Using AEB and exposure compensation together, I would have two "bursts" of three shots each, resulting in a -4, -2, 0, 0, +2, +4. I believe the quicker this can be accomplished, the less chance of problems with scene movement, such as clouds, etc. But since my exposure lock will not remain in place for more than 4 seconds (unless I am mistaken), this may not be the solution I was hoping for.
    I've done this on my Nikon D90 and it definitely is quicker and easier. Unfortunately, your 5D has a timer limitation that prevents this from being as easy as it should be. I couldn't find any option to extend the meter time-out on the 5D.

    The only option I see, which isn't so bad, is to frame the scene as you want it and use EC to adjust the exposure. Take a test shot or two and check the histogram to ensure that it's centered. The beauty of this method is that the histogram of your "zero" shot will always be centered, even if the light changes a little before you start shooting. Of course, this is because EC is always relative to the current lighting.

    Once you've adjusted your EC, you simply apply the +2/-2 adjustments to EC as you wanted to do originally. Except that the images will be taken at +1.7/-2.3, for example. But who cares? Just count the clicks...6 in one direction and 12 in the other. You might even be able to use the Exposure Display to easily apply the +2/-2 bias. This process will still allow you to take the shots quickly.

    Of course, if you have the cover on the eyepiece you can still control EC using the Control Panel. It might also help to set your divisions to 1/2 stop instead of 1/3 stop. In any case, I think it's a method worth pursuing.

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