The 50mm lens is a favourite among many DSLR photographers for topside use because of its wide aperture of f/1.4, which produces images with a very shallow depth-of-field and soft, blurred backgrounds (bokeh). For macro, using a 60mm lens is certainly more versatile and easier to shoot with; however, shooting below _f/_2.8 is quite unique for underwater photography, and the 50mm’s bokeh is simply stunning.

Here are some tips to help you get started using your 50mm lens underwater with a macro port, with an emphasis on using natural light instead of strobes, which will give your images a more organic feel.

Related Reading: Intro to Underwater Photo Composition

1. Because it’s not a true macro lens, the closest focusing distance of the 50mm lens is quite large, at 45cm, so it’s advisable to fix a diopter on the lens or macro port so you can get closer to your subject (e.g., a +4 close-up diopter). Although fine for subjects of a small/medium size, such as a frogfish, anything smaller than ~4cm should be avoided.

2. Before using underwater, practice using the “custom/manual/preset” white balance mode of your camera on land first. It's OK to shoot using auto white balance. You can also fine-tune this in post-production.

3. For the best results, shoot in shallow depths. Stay as close to the surface as possible.

4. Pay attention to the direction of the light. Keep it behind you, or shoot up toward it to get the sun's rays into your image.

5. Set your camera’s focus priority to release. You don't want to fuss with manual focusing.

6. Experiment with setting your camera to manual with the exposure set to slightly brighter than the setting you'd use shooting topside.

Related Reading: How to Pack Your Underwater Camera Gear