Canon R6 Exposures Progressively darker in Continuous Shooting?

LSXPhotog

Motorsports, Automotive, Commerical, & Real Estate
CR Pro
Apr 2, 2015
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www.diossiphotography.com
So an ULTRA strange thing occurred yesterday while shooting a wedding. My typical technique for group photos has been to count down from 3 and then start shooting a sequence of 3-5 images at 1. This way I ensure I don’t get blinkers in my shots. LOL But anyway, now to my point. I performed this task yesterday like I normally would and -for whatever reason- I had the camera on auto ISO. I use auto ISO at weddings fairly often, but during a portrait session in controlled light, I probably shouldn’t have because there was no need. It does make things easier when I want to quickly change aperture on the fly without thinking.

That said, something extremely EXTREMELY odd happened while I was taking my shots. The longer I held the shutter button down, the darker my images became. Like...down by almost 2 stops. It appeared to lower the exposure by 1/3 of a stop per image or more. I had never seen this before at ALL...like, I’ve never experienced anything like this in the past. I wasn’t able to replicate it on ever image, but I could tell when it was happening in the viewfinder because the liveview preview would become darker. At that point I could have taken the camera out of auto ISO, but it wasn’t ruining the shots and I was determined to troubleshoot the situation.

Long story long, I couldn’t identify what was causing this to happen and I wanted to see if anyone else here might have experienced this and what the issue was. The R5 has never done this, but the R6 did. When I get home I’m going to spend a ton of time trying to identify what the cause of this is and I’ll report back. Until then, has anyone had this issue?

Lens used was the RF 24-70 f/2.8L.
 

Joules

doom
CR Pro
Jul 16, 2017
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Hamburg, Germany
Mind sharing the EXIF so that we can confirm how much the exposure and other settings varied between shots?

If I had to take a guess, I would think you had the AF perhaps selected manually and since apparently exposure is heavily weighted towards the AF point in some metering modes, perhaps what ever was under your AF point changed from a bright face to a dark suite or something. That's just a shot in the dark though, without you sharing some more insights.
 
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LSXPhotog

Motorsports, Automotive, Commerical, & Real Estate
CR Pro
Apr 2, 2015
471
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www.diossiphotography.com
Mind sharing the EXIF so that we can confirm how much the exposure and other settings varied between shots?

If I had to take a guess, I would think you had the AF perhaps selected manually and since apparently exposure is heavily weighted towards the AF point in some metering modes, perhaps what ever was under your AF point changed from a bright face to a dark suite or something. That's just a shot in the dark though, without you sharing some more insights.
So I’m sitting here in the airport and you inspired me to take a look.

First, this is the EXIF data for a set of six shots in a row.
Here is one sequence:
1/100 f/2.8 ISO 1,000
1/100 f/2.8 ISO 1,000
1/100 f/2.8 ISO 640
1/100 f/2.8 ISO 400
1/100 f/2.8 ISO 320
1/100 f/2.8 ISO 200

I have exposure safety shift set to ISO. So that was probably an influence here even if I wasn’t in AUTO ISO. I also had the camera on Anti-Flicker because of some mixed lighting. The R5 did not experience this issue at all in the same conditions, but I’ll have to keep my eye on it. Looking back at the set the issue only occurred three times. I noticed it on the second sequence and then I deliberately shot a third sequence longer than normal to see if I could identify anything. When I let my finger off the shutter for a few bit the exposure raised slightly and then when I started shooting again it went back down. I turned on the AF point and it doesn’t look like that had any influence on the shots because it remained mostly static on the eye or the face. I will try to test it back in the office.
 

Mt Spokane Photography

I post too Much on Here!!
CR Pro
Mar 25, 2011
16,603
1,569
Mind sharing the EXIF so that we can confirm how much the exposure and other settings varied between shots?

If I had to take a guess, I would think you had the AF perhaps selected manually and since apparently exposure is heavily weighted towards the AF point in some metering modes, perhaps what ever was under your AF point changed from a bright face to a dark suite or something. That's just a shot in the dark though, without you sharing some more insights.
That would be my thought. A focus point drifting from face or hair to white dress would definitely drop the exposure with the standard metering setting.
 

Nemorino

EOS R
Aug 29, 2020
124
146
What are the values of the exposure correction in the EXIF? Do they change as the Iso?
And which function has your control ring?
 

Frodo

EOS RP
Nov 3, 2012
407
80
I agree with Nemorino. Check the control ring is not set to exposure compensation. The change is about 3.5 stops and is consistent in direction. Unlikely to be spot metering or similar.
 
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