LESSON TWO: HOW TO USE A STROBE

In this lesson I will cover the use of the strobe.  I am using the Intova ISS2000 strobe.  The strobe is necessary because water is a powerful filter of light.    As you descend red quickly gets filtered out.  Yellow is fast to follow.  There are basically three options for restoring the capturing of the colors that exist but are lost to your eye and the camera due to the lack of the full spectrum of light.  First is to use a "red" filter which is actually a balance of red and yellow and has an orange appearance.  The second is to use a strobe to enhance the flash.  Most cameras' built in flash are designed for land use and are not powerful enough to overcome the filtering effect of the water.  The built in flash will also cause "back-scatter" showing the particles in the water thus making the picture grainy. The third method is to combine these two.  You may read that some caution against using both as it can overenhance the reds.  However, I find it much easier to "cool" the color temperature in photoshop than to create it.   Here are some tips to effectively use an underwater strobe.

In the above example, the strobe is aimed too high.  The baby spotted stingray is not being properly lighted.  Setting up a shot is more than lining up the subject in the viewer, it also means aiming the strobe.  Some photographers will use 2 strobes, one for the subject and one for the background.  Shot at 27feet down in Cozumel.

The strobe is now aimed properly so as to light the subject.  However, another important factor is the power setting of the strobe.  In the above picture the power was set to the maximum.  The distance of the shot combined with ambient light created too much light essentially washing out the subject.  A lower setting of 25% to 50% would have been enough.  Another option I have yet to try is the new Intova Diffuser.

The strobe is effectively lighting the subject.  The distance to the subject is actually only about 7 feet.  The Intova Wide Angle Lens allows being closer to the subject.  Being closer is very important as the water contains so many floating particles that the quality is reduced the further away you are.  The strobe has an effective distance of about 12 feet.  This varies of course according to the clarity of the water you are diving in.  Shot in Cozumel at 30 feet down.

The effective distance of the strobe is highighted here in coloration of near vs. the further back branched coral.  The closer coral shows off it's soft brown with reddish highlights brought out by the strobe.  However, the coral behind it is too far for the strobe to effectively reach it.  This is not necessarily bad.  In portrait photography the backgrounds are intentionally muted to highlight the subjects. Both the aim and power level are correct.  Shot in Nassau at 65 feet.

This picture can illustrate either the limitation of the strobe or the effect of improperly aiming.  The area on the left is the focus of the picture.  Although it can  be left this way to show the contrast, there is a less artsy feel to it.  The picture  can be greatly improved as seen on the right.  Shot in Cozumel at 55 feet down.

Using photoshop the picture has been cropped to the area of focus.  The poorly lighted or misaimed area has been removed.  The result is a photo that has  good color depth and emphasizes the spineless coral.  This is where the issue of megapixels comes in.  Having  more megapixels gives the ability to crop photos and still retain printable quality resolution.  I switched from the 5 to the 10 megapixel Intova in order to have this ability.

The strobe must be properly set as to its "preflash."  Many cameras use a preflash to prevent people from closing their eyes when the actual picture is taken.  If the preflash is not properly set, the strobe flash will not line up with the opening of the shutter and taking of the picture.  At 78 feet down this coral at Grand Turk appears like everything else, a greenish blue.  I took multiple pictures, one at each setting to assure the proper preflash.  The picture on the right shows an improvement in the preflash setting. However, it is still not ideal.

This picture has the correct preflash.  The true colors of the coral and the juvenial fish are now being captured.  This is at the recommended preset of "2" on the Intova ISS2000 Strobe when shooting with the Intova IC10.  The strobe can be used with other cameras as well however the preset for the flash may differ.

Taking the image from the left and putting it into Photoshop can help restore color and clarity to the photograph.  I will have a separate lesson on using Photoshop to clean up your pictures.

The combination of the red filter and the strobe worked here to bring out the porcupine puffer.  The ambient light was poor.  Although only about 45 feet down the large rock "finger" at Cabo San Lucas made this a darker area.

At 70 feet down the ambient light was poor and visibility cut to about 15 feet.  However, the combination of the strobe and red filter brought out the incredible colors of the angel fish.  Shot in Cabo San Lucas.

This starfish is brilliant and clear with the richness of its background through the  use of combining the red filter and strobe.  Cabo San Lucas 45 feet down.

The red filter and strobe again combined to help highlight this drummer fish.  The heavy particulate nature of the water is evidenced in the limited background depth.  Cabo San Lucas 40 feet.

Here are a few guidelines for the use of the strobe and red filter.

1.  The red filter is essential for video, and helps in certain still shots as well including some with the strobe.

2.  Where there is enough ambient light the red filter may be sufficient without the strobe.

3.  The combination of the strobe and red filter can be useful in places where there is insufficient ambient light and high
particulate water that limits visitbility and strobe effectiveness.
4.  Practice is necessary to learn the best use of the combination.

To summarize our lesson on strobes...
1.  Strobes are essential as built in flash units are insufficient under water.
2.  The strobe must be properly aimed.
3.  The power level must be set so as to light with out washing out.
4.  The preflash must be correctly set.
5.  The strobe can be combined with red filter under conditions of lower ambient light and highly particulate water that limits visibility
and strobe effectiveness.
6.  Practice is essential.