Snell's Window: Elevate Your Underwater Photography Game

What is Snell's Window?

Snell's Window is a fascinating optical phenomenon observed underwater. Named after Willebrord Snellius, a Dutch mathematician, this effect is a circular window of light visible from beneath the surface, providing a unique view of the world above. When looking upwards from underwater at a steep angle, light entering the water is refracted due to the difference in the speed of light in air and water. This refraction bends the light, creating a 97-degree cone of vision through which the underwater observer can see a compressed, wide-angle view of the above-water environment.

The Importance of Snell's Window in Underwater Photography

For underwater photographers, Snell's Window offers a unique and dramatic compositional element. Capturing this effect can result in stunning images where the underwater environment seamlessly blends with the world above, creating a surreal and captivating scene. Utilizing Snell's Window effectively can add a sense of depth, context, and scale to underwater photos, enhancing their visual impact and storytelling potential.

Settings and Tips for Capturing Snell's Window

To capture Snell's Window effectively, follow these settings and tips:

1. Use a Wide-Angle Lens:

   • Wide-angle lenses (with focal lengths of 16mm or less) are essential for capturing the full extent of Snell's Window. These lenses allow you to include a broad perspective, ensuring the window is prominently featured. A fisheye lens is perfect, but be aware of the full distortion of the lens.

2. Optimal Positioning:

   • Position yourself beneath the surface, ideally at a depth of 6-12 feet (1-2 meters). Look upwards at an angle of about 45 degrees to maximize the visibility of Snell's Window. The further up you look the bigger the window will become. You can use the full window effect by holding the camera parallel to the surface of the water, but partial windows are also very effective.

3. Lighting:

   • Snells window is captured using ambient light; you are exposing for the sunlight that comes through the window. However, Snells window shots are best when combined with a foreground underwater element. You can choose to light this part of the image with strobe or if the subject has a prominent shape, leave it in silhouette.

4. Camera Settings:

   • Aperture: Use a small aperture (f/8 to f/16) to ensure a large depth of field, keeping both the underwater environment and the view through Snell's Window in sharp focus.

   • Shutter Speed: Set a fast shutter speed (1/125 min) to avoid motion blur caused by water movement and to block out the excess ambient light from shooting directly up. Snells window can be great during sunset, then you will likely need to use a little slower shutter speed. In daytime with bright sunlight, your max speed (around 1/250) whilst using strobes might not even be fast enough.

   • ISO: Keep ISO as low as possible to minimize noise and maintain image quality, also to reduce the effect of the bright ambient light.

5. Stability:

   • Maintain buoyancy control and stabilize yourself to prevent camera shake. It can be difficult to achieve this when shooting at such extreme unnatural angles. Also be fully aware of your bubbles, often they drift into the shot so you will need to time your breathing with your shot.

6. Composition:

   • Incorporate interesting foreground elements such as coral reefs, marine life, or underwater landscapes to add depth and context. Position these elements at the bottom of the frame, leading the viewer’s eye towards Snell's Window. Also remember that Snells window, especially partial windows work very well with vertical images.

7. ND Filter:

   • Consider using an ND filter to reduce exposure when shooting snells window in bright mid day sun.

Conclusion

Capturing Snell's Window in underwater photography is a rewarding challenge that can yield breathtaking images. By understanding the phenomenon and utilizing the right equipment and techniques, photographers can showcase the interaction between the underwater world and the surface. With practice and patience, Snell's Window can become a signature element in your underwater photography portfolio, providing a unique perspective that captivates and intrigues viewers.