My 7D Mark II seems to often blow out shots in manual if using auto ISO. Sets the ISO way too high.

[Waddizzle]

That can be caused by a couple of factors. 

First and foremost, is the metering mode.  Evaluative metering is the default setting, and works best for all but the most critical shooting scenarios.  Evaluative mode looks at the entire scene to when reading the light strength.  The other modes use progressively smaller and smaller portions of the center of the scene to read light strength.

Another more suble issue that can crop up is unknowingly locking in exposure settings on successive shots, when you're shooting under quickly varying lighting conditions.  For example, you point in one direction take a shot, and moments later you may turn slightly to take another shot. 

But, the exposure is incorrect on the second shot for some reason.  This used to happen to me a lot, and left me scratching my head on several occasion.  I would be shooting in manual mode, using Auto ISO, which is supposed to compensate for varying light conditions.  I shouldn't be getting under/over exposed shots.

I was completely mystified.  I realized that my thumb might occasionally be brushing up against [ * ], AE Lock, button, which would lock in the exposure for several shots.  I've paid more strict attention to my thumb, and suddenly the random over/under exposed shot has become quite rare.  It only happens when I lose focus of what I'm doing with the camera.

[jimvenice1]

I checked and I was set to evaluative and the shots I was taking were butterflies so I really wanted the center focus part of the image.  I'll give it another try;  perhaps the evaluative took too much of the outer areas into account.  Thank you.

[Waddizzle]

---

@jimvenice1 wrote:

I checked and I was set to evaluative and the shots I was taking were butterflies so I really wanted the center focus part of the image.  I'll give it another try;  perhaps the evaluative took too much of the outer areas into account.  Thank you.

---

Great. 

And, do watch your thumb.  AE Lock defaults to 8 seconds, and the minimum setting is 4 seconds.  On the camera body where I have disabled the button, I don't get any more mystery over/under exposures, not ever now.

So, I think the thumb occasionally hitting [ * ], AE Lock, has been my real culprit all along, not the exposure mode settings. 

[TTMartin]

The 7D Mk II has exposure compensation when using Auto ISO.

If your shots are coming out overexposed when using Auto ISO, make sure you don't have any Exposure Compensation dialed in.

If you set exposure compensation in Av or Tv mode, then switch to M mode with Auto ISO, the exposure compensation will carry over to the Auto ISO in M mode. 

7D Mk II M mode 1/1250, f/8, ISO 1600, (Auto ISO and Evaluative Metering +2/3 Exposure Compensation). 

[RobertTheFat]

---

@TTMartin wrote:

7D Mk II M mode 1/1250, f/8, ISO 1600, (Auto ISO and Evaluative Metering +2/3 Exposure Compensation). 

---

It's interesting how that beetle is camouflaged to look like a bee. I guess it doesn't matter that the butterflies weren't fooled, since they probably don't eat beetles.