Here's a quick trick to get that even white or black background. It can be tough trying to shoot an object and get an even white or black background. Here's what I do to isolate an image. Using the Info Tool (F8) and Curves Adjustment layer helps me identify where I need to paint out areas that need it.
1.) Use the Info Tool to get an RGB reading (Window > Info) 2.) White in RGB is (255, 255, 255) & Black in RGB is (0, 0, 0) 3.) Duplicate the original layer (Command + J) 4.) Add the Curves Adjustment (Window > Adjustments > Curves) 5.) In the Curves Adjustment drag the black triangle to the right (for black background, drag the white triangle to the left) Use the Brush Tool (B) and set the Opacity to around 30-40% 6.) Set the foreground color to either white or black depending on which background color you want 7.) Paint on the Duplicate layer 8.) Use the Info Tool (F8) or the Curves Adjustment to aid in getting even white/black background
if you open the curves adjustment you will see 3 eyedroppers, a black one, a grey one and a white one, select the white on and click on an area you want to make white.... on many photos it is good enough to be done at that stage
Canon 24-105mm L F4.0
Canon 17-40mm L 4.0
Tokina 10-17mm F...