The main difference between you and your camera concerning images is that you have a brain. That one changes the colors you precieve selectively according to what you know a priory about objects and their colors. The camera, even if it's a superior brand like yours
, laks a brain so it has to have some notion about the color of the light involved in order to set the colors it renders. For that it has the presets like daylight , tungsten and so on, or the auto option in which it tries to mimic your brain and figure out the colors by himself. This works not bad in simple situations but in scenes with lights of different types it doesn't do very well. imagine a sheet of white paper that you see indoors under tungsten bulbs. Its real color is on the yellow side but you see it white because you know it's white. You have to tell your camera that it's tungsten light and it will adjust the colors so the sheet of paper will be white. Now in the same scene place fluorescent light too and another sheet of white paper under it. Now you have two types of lighting so the paper lit by tungsten is on e yellow side and the one lit by the fluorescent is on the blue/green side. Your brain knows that both sheets are white and you'll se them approximatively the same bt the camera will balance for one light or the other and the colors of the sheets will be quite different. In these situations there are not many options to correct the colors in camera and post production could be a pain. One solution, but not perfect mind you, is to use custom WB. The principle is simple. Place a white or calibrated18% gray card under the light of your scene and take shot of it, taking care not to obstruct the ligt and to fill the frame with it. Now, in the more primitive cameras like Canon
, you have in the menues the option of the CWB, where you are asked to select the reference image. Select the one with your card and then in camera select costum WB, and you can take the shot. Be aware that the reference image is good only for that specific scene and it may not be good for another point of view. Also if there are different types of lighting that do not iluminate the reference card, the colors won't be "right" for the whole scene. Much simpler is to shoot raw files and place a white or gray card in the scene for the reference shot ( some times it's not possible though) and then take the shot without it and in post production set the WB on the card and apply it too your shot. when using flash the situation is more complex if ambient light is of different kinds. You may choose to shut it down completely or place gels (filters ) on the flash in order to bring its light color to the color of the ambient light.
Canon PowerShot S100
Canon 50D , SIGMA 10-20 f3.5 ,Canon EF 24-105 L IS USM, Canon EF 100/2.8 macro Canon EF 50/1.4 ,Canon EF 85 f1.8,Canon EF-S17-85 4-5.6 Old Tamron 28-300 inherited from my Canon Rebel G film camera