why does it seem that my 5d3 and 1DX both under expose in auto ISO..anybody?

[Northstar]

don't shoot studio...it's action action action and both my cameras underexpose regularly by 1/2 to 3/4 stop....anybody with thoughts on this?

[bdunbar79]

don't shoot studio...it's action action action and both my cameras underexpose regularly by 1/2 to 3/4 stop....anybody with thoughts on this?

Yep.  The 1DX is the worst.  I set up a target in my kitchen once, with a tripod.  I used the 24-105L lens at 70mm and shot the target, on both cameras, in auto ISO, all other settings the same.  With CWA, the 1DX came back with an ISO of 4000, while the 5D3 came back with 6400.  So, the relative differences between the two cameras, with CWA was about 2/3 stop in my experiment. 

The metering obviously matters, and CWA for action will vary wildly, even by just turning your camera a few degrees. 

The problem is solved easily with a 1DX.  I do this.  I "force" my 70-200 f/2.8L II IS lens to stay at f/2.8 in Tv mode.  Just set min aperture to 2.8 and max aperture to 1.0 or whatever, some aperture it can't get to.  Then go back and set ISO safety shift ON.  Next, set your shutter speed to whatever you wish, in my case 1/500 in low light gyms.  Now, set EC to +2/3 or +1, and use CWA.  This works most of the time.  The "meter" on the right hand side will obviously change if you are using other metering, such as spot or evaluative.  Since my shots are centered on players themselves, I just gauge my settings off CWA.  White jerseys sometimes fool the camera in spot metering.

Or, if the gym is relatively evenly lit, I'll set ISO manually to generally overexpose by +2/3 to +1 1/3.  This again of course, is CWA, but don't worry, it will work. 

The 5D Mark III does not require the level of overexposure that the 1DX seems to, which is why I quit using auto ISO, or if I use it, I use EC.  On the 5D3 I never use auto ISO anymore, because I just can't get it to expose the way I want.  It changes too drastically indoors in different places in the gym and changes too much depending on what type of metering you are doing.

[neuroanatomist]

If the 1D X autoexposure is consistently off, you can use AE Microadjustment (up to 1 stop in 1/8-stop increments). 

[Steve Todd]

Your results are interesting.  My 1DX is nearly flawless in all of the auto exposure modes.  I thought my 1D4's were great.  However, the 1DX is even more accurate.  I have noticed that my 5D2 tends to be about 1/8 to 1/3 on the under exposed side, which usually produces fully acceptable images.  On the other hand, I found the 7D I had, would over expose most images by 2/3 of a stop, to a full stop and a half?  So, I guess there are variables in any man made product.  However, after owning everything from film models (FT-B, AE-1s, AE-1Ps, A1s, EOS 620 & 630s, EOS-1, EOS-5, EOS-1n and EOS-1Vs) and digital models (EOS 5D, EOS 5D Mk II, EOS 7D, EOS-1D Mk IVs and EOS-1S X), I don't think I am alone in having been extremely satisfied with all of my Canon products and their precise metering.

I've owned Canon SLR/DSLRs since the '70s and have always found Canon's metering to be outstanding.  In fact, while working partime as a NASCAR photog (1998-2001) my shots were chosen over those from my fellow photog's, primarily because of my accurate exposures (Provia 100F film, with less than 1/3 stop of exposure latitude).  I never told them I relied solely on the camera's auto metering.  Almost everyone (Pro race photogs) in those days used handheld meters and shot manual exposures.  I trusted my equipment (EOS-1n & EOS-1V) and knew how accurate their metering was.  With the quickly moving subjects and constantly changing lighting conditions at most races, my exposure (and focus) "hit rate" was far greater than most of the other folks I worked with.  And that included almost everyone using top-of-the-line Canon and Nikon equipment.

[neuroanatomist]

FWIW, the autoexposure on my 1D X is also spot on.

[Northstar]

Your results are interesting.  My 1DX is nearly flawless in all of the auto exposure modes.  I thought my 1D4's were great.  However, the 1DX is even more accurate.  I have noticed that my 5D2 tends to be about 1/8 to 1/3 on the under exposed side, which usually produces fully acceptable images.  On the other hand, I found the 7D I had, would over expose most images by 2/3 of a stop, to a full stop and a half?  So, I guess there are variables in any man made product.  However, after owning everything from film models (FT-B, AE-1s, AE-1Ps, A1s, EOS 620 & 630s, EOS-1, EOS-5, EOS-1n and EOS-1Vs) and digital models (EOS 5D, EOS 5D Mk II, EOS 7D, EOS-1D Mk IVs and EOS-1S X), I don't think I am alone in having been extremely satisfied with all of my Canon products and their precise metering.

I've owned Canon SLR/DSLRs since the '70s and have always found Canon's metering to be outstanding.  In fact, while working partime as a NASCAR photog (1998-2001) my shots were chosen over those from my fellow photog's, primarily because of my accurate exposures (Provia 100F film, with less than 1/3 stop of exposure latitude).  I never told them I relied solely on the camera's auto metering.  Almost everyone (Pro race photogs) in those days used handheld meters and shot manual exposures.  I trusted my equipment (EOS-1n & EOS-1V) and knew how accurate their metering was.  With the quickly moving subjects and constantly changing lighting conditions at most races, my exposure (and focus) "hit rate" was far greater than most of the other folks I worked with.  And that included almost everyone using top-of-the-line Canon and Nikon equipment.

Reading your comment makes me think of copy variation.   I so so so so frequently have to boost exposure in pp by 1/2 stop if I've decided to shoot auto iso in "m".   I know there is some personal pref in this area but...anyway, I wish I could count on auto iso but I can't, so I've stopped using auto iso for action.

it's interesting to read about your experience....so different.

[Northstar]

don't shoot studio...it's action action action and both my cameras underexpose regularly by 1/2 to 3/4 stop....anybody with thoughts on this?

Yep.  The 1DX is the worst.  I set up a target in my kitchen once, with a tripod.  I used the 24-105L lens at 70mm and shot the target, on both cameras, in auto ISO, all other settings the same.  With CWA, the 1DX came back with an ISO of 4000, while the 5D3 came back with 6400.  So, the relative differences between the two cameras, with CWA was about 2/3 stop in my experiment. 

The metering obviously matters, and CWA for action will vary wildly, even by just turning your camera a few degrees. 

The problem is solved easily with a 1DX.  I do this.  I "force" my 70-200 f/2.8L II IS lens to stay at f/2.8 in Tv mode.  Just set min aperture to 2.8 and max aperture to 1.0 or whatever, some aperture it can't get to.  Then go back and set ISO safety shift ON.  Next, set your shutter speed to whatever you wish, in my case 1/500 in low light gyms.  Now, set EC to +2/3 or +1, and use CWA.  This works most of the time.  The "meter" on the right hand side will obviously change if you are using other metering, such as spot or evaluative.  Since my shots are centered on players themselves, I just gauge my settings off CWA.  White jerseys sometimes fool the camera in spot metering.

Or, if the gym is relatively evenly lit, I'll set ISO manually to generally overexpose by +2/3 to +1 1/3.  This again of course, is CWA, but don't worry, it will work. 

The 5D Mark III does not require the level of overexposure that the 1DX seems to, which is why I quit using auto ISO, or if I use it, I use EC.  On the 5D3 I never use auto ISO anymore, because I just can't get it to expose the way I want.  It changes too drastically indoors in different places in the gym and changes too much depending on what type of metering you are doing.

Bdunbar...thanks, I appreciate your post and will try your suggestions.

[Northstar]

If the 1D X autoexposure is consistently off, you can use AE Microadjustment (up to 1 stop in 1/8-stop increments).

I'll have to try this neuro...thx.

[neuroanatomist]

I so so so so frequently have to boost exposure in pp by 1/2 stop if I've decided to shoot auto iso in "m".

As I said, you can correct it with an AE microadjustment, which basically sets the zero point for the camera's meter where you want it.

[bdunbar79]

If the 1D X autoexposure is consistently off, you can use AE Microadjustment (up to 1 stop in 1/8-stop increments).

Yes, sorry, I didn't mention that.  Thanks Neuro.  Everybody I know who shoots 1DX in auto ISO has to add exposure in post, often times over +1.00 in LR with CWA.  I think one guy set AE to +5/8 and that took care of the problem.  I don't want to say the 1DX underexposes per se, but the files are certainly darker than any camera I have ever had, with auto ISO CWA metering.  This is also common among other photographers I know, so this isn't a strange thing with the 1DX.  Just do AE.

[Northstar]

I so so so so frequently have to boost exposure in pp by 1/2 stop if I've decided to shoot auto iso in "m".

As I said, you can correct it with an AE microadjustment, which basically sets the zero point for the camera's meter where you want it.

I will be doing this...thanks again.