Lens reversal rings basically allow you to mount your lens to your camera backwards. This sounds silly, but it does work. It’s a very risky approach to macro photography, however, and we wouldn’t recommend trying it. If you’re not careful, you can even scratch your front lens element, or worse, your camera’s sensor, which will be exposed the whole time you’re shooting. Lens reversal rings also don’t give you any control over aperture or focus, so you’ll have to set these manually before you begin shooting. A macro extension tube is a cheap and far safer option. Consider lens reversal only when you have no other choice.