Exposure changing while shooting High Speed Continuous and Servo Focus with the R6

[kevinbarre]

I can shoot a static subject in static light using the High Speed Continuous drive mode on the R6, and the first two frames will be correctly exposed, but all subsequent frames will be overexposed. 

Trying to figure out if there is a setting to keep the exposure automatically locked. I have it set for Center-weighted Average metering, and I have "AE lock metering after focus" set to locked, but this doesn’t seem to actually keep it locked when using Servo focus. Also, it's odd that it always jumps up in exposure and will stay there as long as I hold down the shutter. 

I'm using Aperture priority and Auto ISO. For a static shot using High Speed Continuous drive mode and mechanical shutter, I get the following frame stats:

Frame 1: 1/320 F2.5 ISO 2500

Frame 2: 1/320 F2.5 ISO 2500

Frame 3: 1/250 F2.5 ISO 4000

Frame 4: 1/320 F2.5 ISO 5000

Frame 5 (and all subsequent frames): 1/320 F2.5 ISO 5000

I get it that it's an Auto ISO issue, but this does not occur if I set the focus to One Shot. It will hold the exact same exposure for as long as I hold the shutter. Wondering if there's a way to lock the exposure for as long as I have the shutter button held.

I'm not interested in using the AE Lock button to hold exposure as I shoot, even though this DOES fix the problem. I'm wondering if there is a menu setting that will accomplish the same thing for as long as I hold the shutter.

[Tronhard]

I think there is an argument Evaluative Metering, but much depends on the specifics.  I shoot with single point servo auto focus and single point metering with back buttons for both.  It's how I learnt a long time ago but, more significantly, it works for shooting subjects like birds in thick bush where the lighting is all over the place.

[kevinbarre]

I'm using the actual setting "High Speed Continuous," as opposed to "Low Speed" or "High Speed+". I'm guessing it's about 5-6 fps. This is occurring in a static shot—no changes in focus at all, even though it's actually in "Face+Tracking". Have not looked at metadata for focus points, but it's generally in the very center portion as I'm sitting here testing it. 

Rationale for Center-Weighted Average is the fact that I shoot a lot of brides against bright windows. Using Center-Weighted usually gives a better starting point for exposure adjustments on the fly using the wheel. Evaluative usually gives me a stopped-down image to account for the backlighting. I'm happy to use whatever metering mode will work, but my problem appears to occur regardless of the mode I've chosen.

The whole thing is baffling. It seems as if it's continuing to meter after capturing 2 frames, and then locking for the remainder. Or it's just bouncing up a stop after 2 frames.

[Tronhard]

Hi Kevin, and welcome to the forum:

With respect, I am curious why you are reluctant to not use your back buttons for focus/metering.   

It seems to me that your situation having a back-lit subject is a classic case for using spot metering so you can make sure that you are metering the bride's face (not under-exposing because of the backlight on a likely white dress). Since you say 'I'm happy to use whatever metering mode will work' it might be worth giving it a try.

BB focus lock with servo mode, works very well, considering your brides are not likely to be moving a lot.  If I focus on the eye, press the back button and release, it then locks focus on that spot.  If you think the subject will move, just hold your thumb on the BBF button track them. The following is a video by Canon Australia on setting up BBF as I use it: 

If that does not suit you, then look at this video by Vanessa Joy, who is a Canon ambassador and highly-respected wedding photographer, I will point you to  this one video, but it would be worth exploring her videos considering she is something of an expert in using the R-series gear for your genre.

and

[kevinbarre]

I hear you, and I could give it a shot, but first can we all acknowledge that this is really a bandaid solution to an actual flaw in the camera system? None of my other Canon bodies have this issue. Granted they don't have facial tracking enabled, but still...

There's an actual setting in the R6: "AE lock metering after focus" that seems to be working improperly with Servo focus. I have it set to "locked" for all metering options. Again, if exposure bounced all over the place, I would maybe think it was working as desired to evaluate between exposures. But it's changing by one full stop (in unchanging light), only after two correct exposures, and consistently 1-stop over for all subsequent frames. To me that sounds like a flaw. It does this—mind you—EVERY time I shoot, under all lighting conditions and with all lenses, when Servo, Face-tracking, and High Speed Continuous are chosen.

[Tronhard]

From the video by Vanessa Joy, she comments that the settings for the R-series bodies are a different mindset from those of DSLR cameras.  As regards your comment - R6: "AE lock metering after focus" that seems to be working improperly with Servo focus. I have it set to "locked" for all metering options. Also, one of the features of the R-series is that in servo mode they are designed to refocus and re-meter between shots, hence the option to disable that feature.  I think you are a victim of a change in the systems principle design rather than a technical flaw.

Now, I am not a wedding photographer, I am a wildlife shooter but there are some overlapping principles.  I am just offering these videos to see if they will get you back to work successfully.  If I was you, I would actually contact Vanessa Joy directly, considering her expertise with both the gear and the genre.  She is apparently extremely approachable.

[Waddizzle]

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@kevinbarre wrote:

Just tried it—again—using Evaluative, since you were so insistent. Still happens.

Simple shot of my desk. No moving subject, no changing light.

Frame 1: 1/250 F2.5 ISO 1250

Frame 2: 1/250 F2.5 ISO 1250

Frame 3 (and all subsequent frames): 1/320 F2.5 ISO 4000

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Stop allowing the camera to control more than one leg of the Exposure Triangle at the same time.  Try your test again.  Same conditions.  Manual shooting mode with ISO Auto.  Or, use Av mode, but dial in an ISO value.

DO NOT let the camer control more than one leg at a time.

[kevinbarre]

Just tried it. AV with ISO set to 1600. Problem still occurs.

Frame 1: 1/80 F2.5 ISO 1600

Frame 2: 1/80 F2.5 ISO 1600

Frame 3 (and all subsequent frames): 1/40 F2.5 ISO 1600

It appears it's NOT an Auto ISO issue, but a deeper exposure issue. I've got no clue now.

[Waddizzle]

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@Tronhard wrote:

I think there is an argument Evaluative Metering, but much depends on the specifics.  I shoot with single point servo auto focus and single point metering with back buttons for both.  It's how I learnt a long time ago but, more significantly, it works for shooting subjects like birds in thick bush where the lighting is all over the place.

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I sue the same approach for that shooting scenario.  But, I still use Evaluative Metering whenever I am shooting handheld.  

The OP is using EF lenses in a “high speed” continuous shooting mode.  I would be curious to know if he is achieving a focus lock on the good and bad exposures.  That would have been the first thing that I would have checked.  Where and when am I locking exposure?

[Tronhard]

Kevin, you say: "I can shoot a static subject in static light ".  Am I to understand that this is the situation under which you normally work?  What experience I have had with weddings (I have shot a few, but don't consider it my strength), that is a fairly common scenario.  My point is that if that IS the usual situation, why do you need to use servo mode to begin with?

I would have thought that using Eye tracking with non-servo mode and medium/high speed shooting would achieve what you want. 

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[kevinbarre]

Would that not make more sense if the exposure was all over the place, as opposed to jumping up exactly one stop after two frames and then staying there?