1D2 Exposure Problems

[Bill_Forster]

I've got a 1D2 that about 10-20% of my shots are under-exposed significantly, like 1 to 3 stops. I've noticed this on multiple lenses but lately on my Canon 300/2.8 and I've tried different metering modes. These shots are outdoors at daytime with good lighting. I've usually got the lens wide open, shooting aperture priority. Files are saved RAW and viewed using Canon Photo Professional and Photoshop CS. Anybody have any problems with their exposure???
Thanks,
Bill Forster

[Walter_Kimmel]

Take a neutral gray card such as Kodak's, and on a sunny day, using spot metering and the center AF point, shoot the card at a distance that fills the frame. Make sure that the card is at a sufficient angle to the camera so that you don't get a hotspot reflected back at the camera. Check your histogram on review, and the spike of pixels should come out right in the middle of the histogram., or at least within 1/3 of a stop. I use MF and defocus the lens.