Provide a hemispherical view to your photos.

1. Open your image.

2. Use the Elliptical Marquee tool to create a circular selection in the center of the image. Hold down the Shift key as you drag to create a perfect circle.

3. Choose Filter > Distort > Spherize. Set the Amount slider to 100% to produce the maximum amount of spherization (to coin a term). Click on OK to apply the modification.

4. With the circular section still selected, copy the selection and paste onto a new layer (press Ctrl/Command + C to copy and Ctrl/Command + V to paste).

5. Use Image > Adjustments > Brightness/Contrast and move the brightness and contrast sliders each to the right to lighten the fisheye view and increase its contrast.

6. Use Filter > Sharpen > Unsharp Mask to sharpen up the fisheye view a bit.