Canon 6D images way too dark in TV mode

[SpartanDad]

When taking lacrosse and football photos, I prefer to set Canon 6D to TV mode using 1/500 or 1/640 with appropriate ISO for time of day or night. In the Spring in late afternoon / early evening games.  After having no problems for say first 100 photos, the camera in TV mode starts setting aperture too high (say 9, when just before was 4.5 in identical light), thereby creating photos that are way too dark. I shoot with sun behind me, so the natural light is pretty consistent, while the aperture selected automatically in TV mode jumps around wildly.

To avoid missing too many shots when this occurs, I move to Manual mode, keep speed at 1/500 or 1/640, and set aperture to correct number. I'd prefer camera do the work while I zoom in and out. and as the sun begins to set. 

I never had this problem with other Canon DSLR's. Also, the camera behaves once it's totally dark and I'm depending on stadium lights.

Am using Canon 6D with Canon 70-200 mm EF IS II USM.

Suggestions?

[hsbn]

I put an expo-disc (for white balance) on the lens and take a picture. According to Expoimaging, the disc is supposed to a neutral grey exposure. If I use automatic setting on Canon, I would not get the histogram spike in the middle. It is toward the left. But I shoot manual all the time so it has not been a problem to me yet. Just find it's interesting.

[Skirball]

That's interesting.  How far left is the spike?

[SpartanDad]

Thanks very much for response. When this problem is occurring in TV mode, the meter is screaming back and forth between -3 and +3 like a ping pong ball in a lotto cage! Just took it outside now on an overcast evening and it is steady as a rock in TV mode. Problem only occurs in really bright late afternoon (probably early AM too) light.

One thing I am also doing based on another response is changing metering mode from Spot to Evaluative.

[Skirball]

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@SpartanDad wrote:

Thanks very much for response. When this problem is occurring in TV mode, the meter is screaming back and forth between -3 and +3 like a ping pong ball in a lotto cage! Just took it outside now on an overcast evening and it is steady as a rock in TV mode. Problem only occurs in really bright late afternoon (probably early AM too) light.

One thing I am also doing based on another response is changing metering mode from Spot to Evaluative.

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That’s a different situation than the one you were experiencing before (underexposing in Tv).  In this situation you have chosen a shutter speed and ISO and let the camera choose the aperture (Tv mode).  But the ambient light is too bright, so the camera can’t shut the aperture enough to get a proper exposure.  It’ll blink in-between -3 and +3 to let you know that it can’t properly expose given the constraints.

[SpartanDad]

Thanks. Yes, I do set the ISO (probably 200 around this still-bright time in late afternoon with sun behind me) and speed to 1/500 or 1/640. It works great for say 75-100 photos. Then it starts doing the meter bouncing and setting aperture at 9 or higher, when it has been selecting typically 4.5 (lens goes to 2.8). If it doesn't settle down (including turning camera off and on to clean sensor), I move to Manual and put it at ISO 200, speed 1/500, and aperture 4.5 and the photos are perfect again. Using Manual becomes a problem as the sun begins to set and I need the metering to adjust to shadows and then darkness.

I never had this problem with T1i or 20D. I love the 6D other than this issue, but this is main primary use of the camera getting sports photos.

[Skirball]

That's odd.  I'm not sure what that is.  I was incorrect, if the camera can't get exposure in Tv mode it is the aperture that blinks, not the exposure meter markers.  You're not shooting bracketed shots, are you?

[SpartanDad]

No bracketed shots. Thanks for suggesting ideas. Much appreciated.

[Skirball]

Wish I had another suggestion.  The only time I've seen that response (flickering of the exposure tags) is when I've been shooting in brackets in Av in bright light and the shutter speed hits the upper limit when trying to do the low bracket.

[ScottyP]

Did changing it to evaluative metering work? I can kind of picture that when you were in spot metering and in that bright angled light with sun behind you, there could just have been a mix of very bright reflective things and things that were not bright, and the meter going crazy trying to quickly compensate as you move the spot meter around over this mixed value scene.

Would jacking the shutter up to like 2000 or 4000 do anything?

Would lowering ISO to 100 do anything?

[SpartanDad]

Thanks, Scott. It did behave better Friday evening with first football game, although game started a little later (7:30) than when I was having issues in Spring around 5:30, so sun was up but lower in sky. Appreciate the suggestions. Will test those out as well next Friday.