Is there trick to keeping a photo the same size when setting it as a wallpaper or lock screen?

I have been trying for weeks to only magnify a picture a little bit on both my iPad and my iPhone 4S to set it as my wallpaper and lock screen and every time I think I have it the picture jumps to a ridiculous size and it's getting frustrating. Not only that but ever since I updated to the most recent IOS software the pictures I view on Facebook and in my own photo album have been difficult to view because of magnification issues. I swear I've been so tempted to chuck my iPad across the room. Can Apple get this fixed or what? We have the technology right?!