EOS R6 Mark II: Question about why my shutter speed and ISO are acting the way they are

[stcapp1426]

I have an R6 Mark II that I got about 6 months ago, and I am an amateur-level photographer. I shoot in manual most of the time with auto ISO and exposure compensation if I need it. I have the ISO capped at 12800. Today, I volunteered to shoot people at an event, so I set the camera to aperture priority so I could set my f stop and leave it since I was shooting them in front of a prop. I used my Canon EF mount (with adapter) 24-105 lens. My ISO was also on auto. My friend, who also has a Canon mirrorless (don't know which one) was there as well, with a Canon 70-300 EF mount lens. She set hers up the same way as I did. I noticed that my camera chose a very fast shutter speed combined with a high ISO. Shooting the same scene, her camera chose shutter speeds of around 1/200 with a much lower ISO. Why is that? Is there some setting I don't yet know about that's doing that? This has happened once before but I didn't think much of it then because I didn't have another photographer with me where we could compare settings. It seems like the shutter speed and ISO are competing with one another. What's going on? I'd greatly appreciate your help!

Sherri

[stevet1 · Accepted solution]

Sherri,

My apologies. I didn't read your initial post carefully enough.

As you said, the only variables I can see are the cameras and the lenses.

Any chance you can borrow her lens for a few test shots?

Take a couple with your lens, and then a couple of the exact same scene with hers at the same focal length.

See if there's a difference. You could also run the same test on her camera.

I do not know, and have never read anything to suggest that Canon has changed their algorithms for how they achieve that 18% gray in determining "proper" exposure in the intervening years between when her camera came on the market, and when yours did.

I'm just not that knowledgeable.

Steve Thomas

[Waddizzle · Accepted solution]

I suggest that you become more cognizant of how you handle the camera before, during, and between shots.  When electronics fail, the failures tend to be permanent, not intermittent.

I only mentioned BBF because it caused me to become more cognizant of what my thumb was doing.  Coincidently, the issues I was having with the occasional outlier bad exposure seemed to go away.

Again, strive to be more cognizant of how you hold the camera before, during, and most especially between shots.  Not to point fingers, I think your issue is mist likely operator error related.  Electronic failures are reproducible and permanent, almost never intermittent.

[stcapp1426]

I can't tell you what hers is and I'll have to figure out how to tell what mine is. Can that really make so much of a difference?

[deebatman316]

Yes different focal lengths make a difference so does how much stabilization a lens provides. My uncle and I both own EF 70-200mm F/2.8L IS lenses. He owns the version 2 and I own the version 3. Both cameras are the 5D Mark IV. Camera set to Av with the aperture set to F/4. His camera set the ISO to ISO 100. My camera set the ISO to ISO 200. Same exact lighting conditions taken a few minutes apart.

[stcapp1426]

OK I get that different lenses would produce somewhat different results. But this was a stationary scene, and lower light, so it seems odd to me that my camera would choose such a fast shutter speed, dramatically faster than her camera did. It then forces the ISO up creating potential noise. 

[stevet1 · Accepted solution]

Sherri,

My apologies. I didn't read your initial post carefully enough.

As you said, the only variables I can see are the cameras and the lenses.

Any chance you can borrow her lens for a few test shots?

Take a couple with your lens, and then a couple of the exact same scene with hers at the same focal length.

See if there's a difference. You could also run the same test on her camera.

I do not know, and have never read anything to suggest that Canon has changed their algorithms for how they achieve that 18% gray in determining "proper" exposure in the intervening years between when her camera came on the market, and when yours did.

I'm just not that knowledgeable.

Steve Thomas

[stcapp1426]

Thank you. That's a good idea.

[Waddizzle]

Your experience is hard to explain and may not have an explanation. I used to have similar experiences, which defied explanation.  I would have random bad exposures.  But at some point it seemed to have stopped. I will never know why.  All I have is circumstantial evidence.  

The best explanation I have is operator error.  I suspect that my thumb would wander around the rear panel lightly touching controls. I was still new to the body, but not cameras. 

One day I set up BBF.  In hindsight I realized that this gave my thumb a place to go and something to do.  Weeks later I noticed that the occasional over/under exposure issue hadn’t occurred in a while.  In fact, it has gone away and stayed away. 

[Waddizzle]

After a little more investigation into the issue, I noticed that the over / under exposures would occur when I was using One Shot AF.  My tentative conclusion has been that my wandering thumb was touching [AEL] and locking exposure between shots.  

Since I almost never use AEL, I disabled the button.  I can lock exposure by using One Shot AF, which locks the exposure when it locks down focus.

[stcapp1426]

I have it set to AI Focus and I don't even know where the AEL button is on my camera since I've never used it. Worth checking into. Thanks.

[stcapp1426]

It may not. I've been using BBF for some time now, even before I got this camera. The resulting image was exposed OK, it just leaves me scratching my head as to why the camera would choose such a high shutter speed (over 1/1000) in a stationary scene in lower light, and then have to compensate by raising the ISO. 

[Waddizzle · Accepted solution]

I suggest that you become more cognizant of how you handle the camera before, during, and between shots.  When electronics fail, the failures tend to be permanent, not intermittent.

I only mentioned BBF because it caused me to become more cognizant of what my thumb was doing.  Coincidently, the issues I was having with the occasional outlier bad exposure seemed to go away.

Again, strive to be more cognizant of how you hold the camera before, during, and most especially between shots.  Not to point fingers, I think your issue is mist likely operator error related.  Electronic failures are reproducible and permanent, almost never intermittent.