Problems with exposure

[TurtleDownUnder]

I have recently bought a new Canon 5D mark IV and am having problems with exposure.  I am using an older EF 24-105 lens. I have experimented with different metering modes and still seem to have the problem.  Two photos taken back-to-back with exactly the same settings and the same field of view have dramatically different exposures.  One will be just fine, the next completely blown out.  See an example below:

ISO 320  1/400 sec f/14

ISO 320  1/400 sec f/14

Any ideas, suggestions.  Am I doing something wrong or is there a problem with the camera and/or lens?

[Waddizzle]

Are you using One Shot mode?  For this type of shot, I would use One Shot AF mode, and Single Shot drive mode.  

What metering mode are you using?  I find that Evaluative Metering works just fine for 99.99% of my handheld shots.  Sometimes trying to keep the metering system alive, you can inadvertently lock exposure.  One day I noticed that I had locked exposure after reviewing shots on the LCD.

What shooting mode are you using?  You should be able to see the bad exposures in the viewfinder display.

[TurtleDownUnder]

I was using M - manual shooting mode for these shots and high speed continuous shooting.  But it doesn't matter.  I have the same problems on P (program) and without continuous shooting.  One shot will look fine and then the next shot (same settings, same subject matter) is completely over exposed.  Really frustrating!

[ebiggs1]

"One shot will look fine and then the next shot (same settings, same subject matter) is completely over exposed."

How often does this happen?  Once in a long while, I will say nothing is wrong. Otherwise you may want to have Canon look at it.

[TurtleDownUnder]

Unfortunately, it is happening quite regularly.  Sadly, I live on a remote island in the far north of Australia, so getting Canon to have a look at it isn't that easy.

[ebiggs1]

Easy or not, your solutions are service or new.  

[Waddizzle]

BTW, I think the first shot is under exposed.  The second shot is obviously overexposed.  Make sure the camera is not trying to  capture a set of HDR exposures.  You can either find the setting in the menus, or reset the camera back to factory defaults.

I think shooting at f/14 is unnecessary when shooting with a wide angle focal length.  With a focal length of 24mm, an aperture of f/8 should be sufficient.  This will allow you to raise the shutter speed.  I would want to use at least 1/1000 for these shots.

[Peter]

My two thoughts:

1. stuck aperture

2. wrong EXIF

The first image has readable EXIF, the second one not. The second one is also a small image so it is hard to see any change in DOF.

BTW, your firmware is 1.0.4. Latest is 1.1.2.

[Ray-uk]

The 24-105 Mk 1 is prone to having a broken internal cable which can give intermittent focusing and/or aperture control. To check this put the camera into  M mode, look into the front of the lens, hold the DOF button in and change the aperture through all values, you should be able to see it change at each step. Try this at different zoom levels.

[Waddizzle]

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@Ray-uk wrote:

The 24-105 Mk 1 is prone to having a broken internal cable which can give intermittent focusing and/or aperture control. To check this put the camera into  M mode, look into the front of the lens, hold the DOF button in and change the aperture through all values, you should be able to see it change at each step. Try this at different zoom levels.

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I am not totally convinced that the OP is using the EF 24-105mm f/4L IS USM.

That is good advice on how to test an automatic aperture.  It helps to use a tripod, or look into a mirror when you do it.