Who among us dives, and certainly noticed the phenomenon of diminishing Underwater photography Light & Color as you dive deeper. Standing behind this phenomenon are some interesting physical laws
First, the surface of the sea serves as a huge semicircular mirror, so that on the transition from the over the water medium to that below, we lose a fair amount of white light depending on the angle of light’s impact on the surface of the water. For more information on this phenomenon, we can read about Fresnel laws that define the behavior of light waves in the transition between mediums in different densities.
Second, the water body acts as a giant blue filter that absorbs most of the radiation from the sun. Water disperses and selectively absorbs wavelengths from the spectrum when long wavelengths penetrate shallow depths and short wavelengths can penetrate deeper into deeper depths. This is why the red disappears after 15 meters and purple, green and blue reach deeper depths. When we dive, the colors disappear accordingly.
The implications of the absorption of light and its decline on us as photographers are expressed, if not, in additional financial expenditure.
We have two options:
Designed to return colors that have been filtered by the water and gives the possibility to get a colorful result in natural lighting conditions (sun). The filters are divided into two main types – external (wet) filters that are externally mounted on the chassis and dry filters on the inside of the enclosure (between the lens and the front of the case).
Advantages and Disadvantages:
– There is a possibility to play with it as needed during the dive.
– Underwater assembly only, so as not to create an air bubble that will interfere with photography.
– High production costs which increase its price.
– Fixed diameter suitable for only a specific case / lens!
– A great chance of light reflections in the filter itself, which may confuse the focus system within the camera and be seen in the picture.
– Hardness and thickness which make it “swallow” a lot of light (relatively).
– Inserting when packing the camera in the case.
– Made of gelatin and easy to fit for all types of cameras and cases.
– Low material cost and the price mainly includes engineering in the product.
– is assembled inside the case so you can assemble external accessories and still take advantage of filter features.
– Minimum “light absorption” by the filter.
Please note that we choose a filter suitable for our needs and the color of the water in which we wish to take pictures. In most companies, the filters are manufactured for clear water, such as the Red Sea and green water, such as the Mediterranean Sea or the Sea of Galilee.
In English it is customary to call the flash a “strobe” and an underwater flash called “Substrobe”. The flash artificially produces a white light similar in composition to that of our sun, thus “bringing life back” to the lost colors of the gray objects we meet underwater.
“But wait, my camera has a built-in flash! I do not need it.”
This is a common mistake – using an external flash over an internal flash in underwater photography will turn a bad picture into a good picture, or even an excellent picture!
There are many reasons why you should not use the camera’s internal flash outside the water, but we will not expand on them here. Under water, and even more so, there are a number of reasons for not using the built-in flash:
Backscatters – This is caused when light from the flash hits the particles in the water in the lens field of vision and is returned to it. This causes snow to appear in the image. The simple solution is not to use the flash (possible at a shallow depth of 15 meters in clear seas) but then we lose the colors in depth. The simplest and most effective solution is to remove the source of light from the plane of lens, causing the light hitting the particles to return back at an angle that is not visible in the photograph. An external flash mounted on a long arm comes to answer this exact problem.
Reflections – most fish have scales that reflect light very well, causing an ugly reflection and loss of details on the body of the fish photographed when using the internal flash. This is imilar to the phenomenon of backscatters. An external flash mounted on a long arm comes to answer this exact problem.
Saving the battery – Due to the increased absorption of light in the water, the internal flash is very laborious. This causes increased energy consumption and a long wait between shooting and shooting until the flash is loaded. An external flash that does not use camera batteries comes to answer this exact problem.
Steam and humidity in the dive package – yes, yes – using the internal flash causes vapor to form inside the case! how? When we close the case at home or in the diving club, there is humidity in the air (yes – also in Eilat). This moisture does not interfere with us as long as the temperature outside the case is equal to that inside. Using the internal flash significantly increases the temperature inside the case and condenses moisture into the case , the lens and the port. This causes the reduction of the contrast in the images or the total masking of the image. An external flash that is completely separated from the chassis is designed to answer this problem precisely. In this context, it is possible to put silica gel bags in the dive case, which absorbs the accumulated moisture in it (and this is probably not what will save the camera in case of leakage and water penetration).
Lighting directions and interest in photography – Assembling the flash or flashes on adjustable arms allows us to better control the direction of lighting our objects and create more interesting images.
This shows a picture taken at sea with the camera’s internal flash and poor conditions that highlight the appearance of light reflections from floating particles:
Method of synchronization with the camera – There are two common methods: (a) Wired – The flash is connected to the camera with a special cable that connects to the case and through to the camera’s hot-shoe. This method requires that there be two conditions: a camera with a hot shoe and a case with a suitable connection. (B) Wireless – The external flash functions as a slave flash and flashes as an immediate response to the flash of the internal flash. This method is particularly common in compact systems.
Work depth – identical or larger than that of the case, otherwise we will be limited to the depth of the work of the flash
Cover Angle (Flashlight Area) Using wide angle lenses (or fisheye), we want the flash coverage angle to be at least the same as the view angle of the lens so that areas that do not receive dark areas. In the case of using Classic Fish lenses (a view angle close to 135 ° (underwater) we will need at least two flashes to cover the entire frame area.
Charging Time – Good load times are considered and 1.5-2.5 seconds between full power flashes. In practice, there are few cases in which we use full power, so the load times are significantly shorter.
Battery Flashes – Since we cannot replace batteries under water, it is recommended to select a flash capable of more than 100 full power flashes for a battery / battery pack.
Guide-number – This is the figure that indicates the power of the flash which we can later use to calculate the intensity of the illumination according to the distance table from the object and the reduction in use. It is possible to compare flashbacks according to this data, but note that the measurement units are the same.
Manual control – underwater photography makes extensive use of manual control of the flash. A flash is generally considered to be better as the possibilities for controlling its illumination power are greater.
Weight and size – True, size is relative, but still – if we are looking for ease and convenience in carrying the system, or frequent flights to diving destinations around the world, we should look for a small and light flash.
It’s time to shoot, uh, pay.
Great. After we have clarified all the technical details about the equipment and adapted them to our measurements, skills, wishes and dreams, we have a complete system with everything we need to start shooting underwater. Where should you buy all this equipment?
Different people, different preferences for purchasing at a particular photo store. Sometimes the considerations are ideological (a formal importer compared to a gray importer), sometimes the considerations will be of convenience (today you can order everything via the Internet to your home) and sometimes it will be a net economic consideration (price versus price).
If we decided to purchase a compact camera-based system, we have the same 3 options from the previous section; only this time there is a surprise. Chances are we’ll find our whole set of dreams in the canoe – camera, case and flash. The store imports most of the leading underwater photography brands and if we find a camera they do not import, you can always contact them please do so.
The quiet and the security that there is always to whom to turn to in the event of a malfunction or just help in operating the equipment and tips for starting – worth the extra price – if any.