7D and 550D white balance issues

Normal, I suggest you seek some knowledge about white balance:

How to accurately position the color temperature? (Under normal circumstances, from 10 noon to 2 pm, with a clear and cloudless sky and no direct sunlight, standard daylight is about 5200~5500°K. The color temperature of news photography lights is 3200°K; general tungsten The color temperature of filament lamps, tungsten lamps used in photo studios for taking black and white photos, and ordinary light bulbs is about 2800°K. Because the color temperature is low, the photos taken in this case will appear yellowish in color after they are enlarged. The color temperature of general fluorescent lamps is around 7200~8500°K, so photos taken under fluorescent lamps will appear cyan. This is caused by the mismatch between the color temperature of the shooting environment and the color temperature set by the shooting machine.

The author did not introduce the shooting environment, so I cannot conduct a more detailed analysis.

But as long as the white balance of the camera is consistent with the color temperature of the shooting location, there will be no color cast.

If you find it difficult to understand, please read the manual and learn to customize the color temperature. This is the most standard method