Shooting macro underwater is a great way to start because their are plenty of subjects and it can be relatively easy. These tips will help you perfect your underwater photography macro skills.
As the saying goes in underwater photography (and not only in macro), "get close, and when you think you are close enough, get closer." Eliminating the amount of water between you and your subject is the starting point for creating colorful and sharp underwater images. The water contains countless tiny particles which are not that distracting to your eye, but when lit up by your strobes, ruin images. Take advantage of the close focusing ability of your macro lenses and get as close as possible. Even in the worst conditions macro lenses can get close enough that particles won’t be that much of problem if the strobes are positioned correctly away from your lens. To get close, you need to have excellent buoyancy skills. Additionally, there needs to be ample room for your port. Breaking corals or disturbing the environment is not an option! Be aware of your surroundings at all times. Steadying yourself should be limited to placing one or two fingers on a dead part of the reef and keeping your body off of the reef altogether.Try and get as close as possible to your subject when shooting macro. Be careful though, as some subjects may be skittish and flee if you approach too close. With point and shoot cameras, turning the camera to macro mode will allow you to focus closer to the subject (it decreases the minimum focus distance), but don’t rely on zooming. Make sure that you physically get as close as your camera can focus. You’ll also find that the more you zoom in, the harder it will be to focus, so make sure to steady yourself when shooting. That said, some point and shoot camera's macro mode requires such close focusing that (and this may be the only situation this holds true for in underwater photography) using it will require you to get too close. In these circumstances turn off macro mode, get as close to the subject as possible and use your cameras optical zoom.
Careful FocusingWhen shooting 1:1 macro at 60mm and longer focal lengths, the depth of field becomes very small. What that means is that the range of focus beyond the main focal point is limited (sometimes to just a few millimeters). To get the subject in focus, it is often necessary to use very tight apertures. However, using wide apertures with your macro lenses at high magnification can lead to dramatic images, that can draw your viewer into the image. This will blur the background and most of the subject except for the focal point. However, getting the plane of focus exactly where you want will be much more difficult than with narrower apertures. You can learn more about creative low depth of field images in the article about Bokeh.
Using a low aperture can blur a background
The solution to the depth of field problem is to shoot at tight apertures (increase your f-stop). Even when using narrow apertures it can be tricky to get your plane of focus exactly where you want when shooting with long focal length macro lenses . A steady hand and subject are often required. When you want the greatest depth of field possible, use small apertures like f/22.
Focus on the Eyes
When shooting an animal, you will want to focus on the eyes. If only one thing is in focus, it must be the eyes. When selecting a focal point, always keep in mind that one third of what is in focus is in front of the exact point of focus, and two thirds falls behind it. So, if you want the mouth and the eyes to be in focus, try focusing somewhere in between the two. If you absolutely need to have the entire subject in focus, a good trick is to keep your subject parallel to the camera. Although a straight on side shot is usually not that interesting, most of the visible part of the subject will fall within the depth of field and the entire animal will be in focus.If you are having trouble making the entire subject sharp, shoot a side shot so the entire subject falls on the same plane of focus
In situations when the depth of field is very low and the subject is very small, it can be difficult to get the focal point exactly where you want it. When this is the case, award winning macro photographer Keri Wilk suggests to bracket focus. He explains that by "slightly rocking the camera while taking multiple exposures you can ‘bracket focus’ to ensure that the plane of focus is exactly where you'd like it."
Create Contrast Between Foreground and Background
Often times the background becomes an issue in macro shots. Distracting pieces of reef, rubble, or flora can get in the frame. This creates unsightly clutter in the image that detracts from its impact. As mentioned, when shooting at 1:1 the depth of field is very small, so as long as whatever is in the background is beyond the depth of field, it will be blurry. If, for instance, the background is a colored sponge or coral that fills the frame it can make a nice blurred color background. However, sometimes distracting rocks are even more unsightly when blurred.This is a very interesting subject, but the image is not that effective because there is little contrast between the subject and the background Many macro photographers try to eliminate a noisy background by positioning themselves at a specific angle where the subject only has open water behind it in the frame. Obviously this can't always be accomplished and it should go without saying that removing anything from the frame by physically displacing it, or moving animals to different backgrounds is out of the question. However, by positioning yourself below the subject and shooting up, you give yourself a better chance of only having open water in the background.
Chances are you have seen many macro shots with solid black or blue backgrounds. This a great technique for creating contrast between the subject and the background. Getting a black background is not that difficult as long as there is open water behind the subject. The first step is to increase your shutter speed and use a narrow aperture to minimize the amount light reaching the sensor. You will notice that if you don't use strobes at these settings, the entire image will be black. If there is only open water behind the subject, then when your strobes fire they will light the subject and the open water will be so underexposed it will be black, creating the black background. Note that your histogram will indicate you have an underexposed image, but that's desirable in this case. For more on histograms refer to the Taking Control Of Your Images With Manual Settings article.Shooting up into open water with high apertures and fast shutter speeds can create black backgrounds You can also solve the cluttered background issue with some of the creative lighting techniques we described earlier – like side lighting, or top lighting, which can help isolate the subject from the background. Because it was impossible to get down low enough to shoot up at the subject, side lighting was used to try and minimize a distracting background An obvious technique is to seek subjects that are on interesting backgrounds. Interesting patterns are plentiful in the underwater world. Gobies resting on coral polyps, shrimps on sea stars and fish on sea fans are some examples of how sharp backgrounds can add to the image. Use a tight aperture to maximize the depth of field to keep the background in focus as much as possible. Many underwater macro shots are just of these patterns and are considered abstract shots. Visit the Guide To Underwater Abstract Photography for more on this. Patterns can make interesting backgrounds for macro images
One of the great things about macro photography is that there is no shortage of subjects. Everything from a tiny bubble to a small fish to the patterns of a coral polyp to a rare crustacean make great subjects. Very often we skip past all the common fish and invertebrates on our dives, but these "common" subjects are still breathtaking to most of the population that will never enter the ocean. Of course, it is very exciting to locate rare and interesting macro subjects. To do this, it is invaluable to have some knowledge of where to find these animals. Study the subject you want to photograph and the overall marine life of the particular destination before getting in the water. It's not surprising that the photographers that seem to know the most about habitat they are diving in often create images of the most interesting subjects. If you really want to shoot a Coleman shrimp, spend the entire dive checking out fire urchins as that's the only place to find them. There is simply no way to spot a pygmy seahorse unless you know what kind of coral to look on. A little research before diving, can go a long way while shooting.
Knowing where a Coleman shrimp lives, on a fire urchin, is the only way to find them. ,