First off, I wouldn't call that an underexposed photo. The waterfall is white. The shadows are dark, but there is just too much dynamic range for most sensors to capture it all.
Dynamic range is the camera sensor... and a t3i is old tech for its sensor but to be fair, so is the t5i... just with the latest t6i has the sensor upgraded.
The lack of sharpness is the lens. A kit lens just isn't going to be tack sharp. I can't read the EXIF data but the other thing that will affect sharpness is the ISO. If you shot this on a t3i with pretty much anything above ISO 800 then you aren't going to have a sharp picture. Then the shutter speed could affect it. Because the still objects seem sharper than the things that can move, like leaves that can blow in a breeze.
Mainly-- your camera can get sharp pictures, but you need to learn the factors that make something tack sharp and master those. Because getting new gear won't affect your shots until you know how to use what you have to its fullest potential.[/QUOT
I don't think I shot this at anything higher than 800iso.... The only thing I know I'm doing wrong is getting the right f-stop for the right focal length, but I can't figure out how to do this, like I said originally, it's hard to understand lol