Jeff_W wrote in post #19002887
So leave the peripheral illumination correction (PIC) off?? How do I turn off HTP? I never saw that in my on screen menus
I always leave PIC turned on when shooting Canon lenses, and OFF for non-Canon lenses. Canon does NOT provide lens profiles (needed for PIC) for non-Canon lenses. PIC has no effect on raw (.cr2) files, ever. HTP should be in your menu system. I don't have a T2i, but it is in the RED menus on my 80D. On my camera it is listed as, 'Highlight tone priority'. For you own sanity, turn off ALO and HTP, and never ever touch them again. Ever. Never.
If you are interested in getting the most out of your camera, consider acquiring a program that can work with raw (.cr2) files. Lightroom is most excellent, but costs money. Digital Photo Professional (DPP) is free from Canon, but is a bit more, OK - a lot more, cumbersome to use. If you are happy with the JPG output from your camera, don't fall for the "you have to shoot raw" drivel. Is raw more powerful? Yes. Is raw necessary? No. If you get white balance and exposure correct in camera, you don't NEED to process raw files. I use Lightroom extensively with my FILM photography, which has no raw files.
Lastly, keep firmly in the center of your mind that I am posting how I do things. They are only suggestions. Ask 10 photographers any question, and you'll get at least 11 different answers. Take it all with a grain of salt, then go do what works for you.
80D, bag of lenses, box of lights, other toys.