While using the Crop Tool in Lightroom, Control -click (Mac) | Right Mouse -click (Win) in the image preview area to access a number of crop-related features including: Reset Crop, Crop as Shot, Constrain Aspect Ratio and Crop to Same Aspect Ratio. Or, you can use the following shortcuts:
- Command + Option +R (Mac) | Control + Alt + R (Win) to reset a crop.
- Option + (Mac) | Alt + (Win) select an aspect ratio from the Crop tool’s drop down to apply the new aspect ratio and reset the crop to the image bounds.
- When cropping an image, double-click in the image preview area to apply the crop and dismiss the Crop tool.