5 Tips for Taking Underwater Photographs

 

5 Tips for Taking Underwater Photographs

Stephen Frink is among the world's most frequently published UW photographers, a Canon EXPLORER OF LIGHT and the publisher ALERT DIVER magazine. These are his words and images....
Each year for the past three decades I have taught a series of underwater photo seminars, and it is interesting to see how often a few of the same mistakes perpetuate, student to student, year to year.  Here are five quick tips to make underwater photography more successful, more quickly:

5 Tips for Taking Underwater Photographs

Stephen Frink is among the world's most frequently published UW photographers, a Canon EXPLORER OF LIGHT and the publisher ALERT DIVER magazine. These are his words and images....
Each year for the past three decades I have taught a series of underwater photo seminars, and it is interesting to see how often a few of the same mistakes perpetuate, student to student, year to year.  Here are five quick tips to make underwater photography more successful, more quickly:

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5 Tips for Taking Underwater Photographs

Photo by: Stephen Frink

1. Estimate Distance Properly

Even autofocus cameras require accurate distance estimation, for there are huge variables in exposure as a function of distance. Water is 800 times denser than air, and is typically cyan in filtration as well.  All this is complicated by the fact that we see the world in “apparent distance” underwater.  Water magnifies; so something that looks like it is 3 feet away is truly 4 feet away.  This isn’t a huge problem for focus generally, but without good spatial estimates it is impossible to choose the optimal F-stop or aim the strobe correctly.  
During our seminars the first task of the first dive is to kneel in the sand three feet away from a target of average reflectance and shoot a series of photos at full power on the strobes and half-power settings.  Once those exposures are analyzed, and we know what is the correct F-stop at three feet, we can interpolate proper exposure for getting closer.  And also to an extent we can judge the exposure correction for working further away, but the effect of the strobe greatly diminishes after about 4-feet so then we get into the realm of ambient light rather than artificial light from the strobe.  But, al of this is predicated on accurately and consistently being able to estimate distance.

1. Estimate Distance Properly

Even autofocus cameras require accurate distance estimation, for there are huge variables in exposure as a function of distance. Water is 800 times denser than air, and is typically cyan in filtration as well.  All this is complicated by the fact that we see the world in “apparent distance” underwater.  Water magnifies; so something that looks like it is 3 feet away is truly 4 feet away.  This isn’t a huge problem for focus generally, but without good spatial estimates it is impossible to choose the optimal F-stop or aim the strobe correctly.  
During our seminars the first task of the first dive is to kneel in the sand three feet away from a target of average reflectance and shoot a series of photos at full power on the strobes and half-power settings.  Once those exposures are analyzed, and we know what is the correct F-stop at three feet, we can interpolate proper exposure for getting closer.  And also to an extent we can judge the exposure correction for working further away, but the effect of the strobe greatly diminishes after about 4-feet so then we get into the realm of ambient light rather than artificial light from the strobe.  But, al of this is predicated on accurately and consistently being able to estimate distance.

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1. Estimate Distance Properly

Photo by: Stephen Frink

2. Choose the Right Lens for the Subject

This is a corollary of #1 above, for given the distance limitations and the need to get close, there is only a small universe of subjects appropriate for any particular lens.  OK, a zoom lens might have a bit larger universe, but whatever lens is in use, an underwater photographer must restrict their vision to the appropriate subject. If you see a pygmy seahorse while cruising the reef with your 15mm wide-angle. Tough.  And if the whale shark swims by while you have an extension tube mounted.  Double tough. Find the subjects that are right for your optic and don’t waste shots and creative energy on those that aren’t.  Make sure your vision, and subject quest, conforms to the lens you have in place.  Unlike topside, during a dive you can’t stop and swap lenses while swimming about.  There are some wet lenses that add wide-angle or super macro capability to some systems, but typically you’ll need to decide what lens you wish to mount inside your camera housing, and then find suitable subjects.

2. Choose the Right Lens for the Subject

This is a corollary of #1 above, for given the distance limitations and the need to get close, there is only a small universe of subjects appropriate for any particular lens.  OK, a zoom lens might have a bit larger universe, but whatever lens is in use, an underwater photographer must restrict their vision to the appropriate subject. If you see a pygmy seahorse while cruising the reef with your 15mm wide-angle. Tough.  And if the whale shark swims by while you have an extension tube mounted.  Double tough. Find the subjects that are right for your optic and don’t waste shots and creative energy on those that aren’t.  Make sure your vision, and subject quest, conforms to the lens you have in place.  Unlike topside, during a dive you can’t stop and swap lenses while swimming about.  There are some wet lenses that add wide-angle or super macro capability to some systems, but typically you’ll need to decide what lens you wish to mount inside your camera housing, and then find suitable subjects.

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2. Choose the Right Lens for the Subject

Photo by: Stephen Frink

3. Use Artificial Light

Color happens underwater with the creative application of artificial light.  The full spectrum light from the sun goes away as a function of depth, and it happens selectively.  First the warmest colors disappear, the reds and the oranges.  With greater depths the yellows fail to record, until by a depth of about 30-feet on blues and greens remain in available light photographs.  So, we take our light with us, typically strobes, although there is a hope that LED technology may someday create an artificial light source suitable for our underwater cameras that now shoot both stills and video.  But, the density of the medium (800 times more dense than air) requires a lot of light, and in the present state of technology, that comes from strobes.  The built-in camera strobe is generally insufficient, both in terms of power and especially in terms of placement.  (See discussion of “backscatter” below for explanation).

3. Use Artificial Light

Color happens underwater with the creative application of artificial light.  The full spectrum light from the sun goes away as a function of depth, and it happens selectively.  First the warmest colors disappear, the reds and the oranges.  With greater depths the yellows fail to record, until by a depth of about 30-feet on blues and greens remain in available light photographs.  So, we take our light with us, typically strobes, although there is a hope that LED technology may someday create an artificial light source suitable for our underwater cameras that now shoot both stills and video.  But, the density of the medium (800 times more dense than air) requires a lot of light, and in the present state of technology, that comes from strobes.  The built-in camera strobe is generally insufficient, both in terms of power and especially in terms of placement.  (See discussion of “backscatter” below for explanation).

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3. Use Artificial Light

Photo by: Stephen Frink

4. Avoid Backscatter

Those ugly, disgustingly annoying, white specs that inevitably show up in your otherwise stunning photographs are referred to as “backscatter”. You can digitize your photo and retouch to get rid of the particles, or you can shoot it right to begin with. Assuming you are working in reasonably clear water, for some days on some reefs are so miserably dirty that no amount of imaging skill can return a shot free of backscatter, but there are certainly tricks that put the odds of a backscatter-free photo in your favor.
• Aim the strobe properly – Avoid lighting the particles held in suspension between the lens and the subject.  Use articulated strobe arms to move the strobe above and away from the lens.  With this technique, most of the particles are not illuminated, and those that are get rim light instead of being blasted with full-frontal light.
• Control the ambient light – Your shutter speed/aperture combination determines how much ambient light records in the background.  Obviously white particles of backscatter are less obvious against a light blue background than a dark blue background.  For this same reason, it is hard to shoot wide-angle at night unless the visibility is extraordinary.  Otherwise the white particles are disturbingly obvious against the black background.
• When all else fails, shoot against a busy background – Sometimes no level of creative lighting or tweaking ambient light will preclude backscatter.  In this case, your only option may be to find visually confusing backgrounds to hide the particles.  Shoot against the hull of a wreck instead of the open crow’s nest.  Find a colorfully encrusted reef overhang instead of shooting angelfish in midwater.

4. Avoid Backscatter

Those ugly, disgustingly annoying, white specs that inevitably show up in your otherwise stunning photographs are referred to as “backscatter”. You can digitize your photo and retouch to get rid of the particles, or you can shoot it right to begin with. Assuming you are working in reasonably clear water, for some days on some reefs are so miserably dirty that no amount of imaging skill can return a shot free of backscatter, but there are certainly tricks that put the odds of a backscatter-free photo in your favor.
• Aim the strobe properly – Avoid lighting the particles held in suspension between the lens and the subject.  Use articulated strobe arms to move the strobe above and away from the lens.  With this technique, most of the particles are not illuminated, and those that are get rim light instead of being blasted with full-frontal light.
• Control the ambient light – Your shutter speed/aperture combination determines how much ambient light records in the background.  Obviously white particles of backscatter are less obvious against a light blue background than a dark blue background.  For this same reason, it is hard to shoot wide-angle at night unless the visibility is extraordinary.  Otherwise the white particles are disturbingly obvious against the black background.
• When all else fails, shoot against a busy background – Sometimes no level of creative lighting or tweaking ambient light will preclude backscatter.  In this case, your only option may be to find visually confusing backgrounds to hide the particles.  Shoot against the hull of a wreck instead of the open crow’s nest.  Find a colorfully encrusted reef overhang instead of shooting angelfish in midwater.

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4. Avoid Backscatter

Photo by: Stephen Frink

5. Be Aware of Ambient Light Levels

At any given ISO, the ambient light in the background records as a function of the aperture of course, but also the shutter speed. With any typical exposure in underwater imaging there will be both the vertical light that comes from the sun, and the horizontal light that comes from the strobe, and each has variables.
• Vertical light – This light variable is affected by depth, time of day, cloud cover at the surface, surface conditions (choppy seas reflect more light back to the surface than slick calm seas), and the turbidity of the water.  The camera’s light meter will give an indication of the amount of available light on the scene, but the choice of shutter speed used will therefore affect the aperture. Creatively changing shutter speeds to match the aperture setting required by the strobe is an important skill. • Horizontal light – This is affected by strobe power (most strobes have multiple settings), strobe-to-subject distance, and subject reflectance.  Finding the right ratio of light between that required by vertical and horizontal light sources is important.


5. Be Aware of Ambient Light Levels

At any given ISO, the ambient light in the background records as a function of the aperture of course, but also the shutter speed. With any typical exposure in underwater imaging there will be both the vertical light that comes from the sun, and the horizontal light that comes from the strobe, and each has variables.
• Vertical light – This light variable is affected by depth, time of day, cloud cover at the surface, surface conditions (choppy seas reflect more light back to the surface than slick calm seas), and the turbidity of the water.  The camera’s light meter will give an indication of the amount of available light on the scene, but the choice of shutter speed used will therefore affect the aperture. Creatively changing shutter speeds to match the aperture setting required by the strobe is an important skill. • Horizontal light – This is affected by strobe power (most strobes have multiple settings), strobe-to-subject distance, and subject reflectance.  Finding the right ratio of light between that required by vertical and horizontal light sources is important.


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5. Be Aware of Ambient Light Levels

Photo by: Stephen Frink

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