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    June 05, 2018 5 min read


    Would it be fantastic if you could have one compact underwater lighting unit that combines a flash and constant video light? My customers often ask if such a thing exists, and yes, there are few examples out there like the monstrous i-Divestite Symbiosis, where a large strobe unit has been made even larger by slapping a video light on top… like another head would be sewed-on (it’s alive!) But in reality, anything that could be called compact just does not exists, and there are few good reasons for this. Technically combining a xenon flash tube with an electrical capacitor and a heat emitting LED array is difficult. And what about the power source? The power needs of a flash tube and LED light are very different. It just might be that these two can never be properly combined. A radical new thinking is needed. How about an LED flash?

    One of the most visible changes in underwater photography of late has been the advancement of LED technology. Gone are the expensive Halogen and HID video lights. Today, a basic self-contained LED torch easily trumps an advanced underwater video light of yesteryear in power output. One thing that has not changed is the flash tube. The basis of today’s flashgun was invented in the 1930s and portable xenon filled flash units have been almost unchanged since the 1970s. In the end, the flashgun provides a fast blink of light, nothing more. Surely today’s LED lights are capable of this.

    Lateral thinking: Smart Focus LED flash

    The Weefine Smart Focus 6000 video light is sold as a multi-colour, spotting/video light that boasts 6000-lumen white beam and AFO functions. It also has something called a strobe mode. According to its spec, it can fire an 8000-lumen 5000k flash, which is synced from the camera via a fibre optic cable, exactly like you do with a traditional underwater flash gun. There is no separate light source for the flash. Its source is the same main COB led array that produces the constant light. A clever thing is that you can use the same LED light source in low power setting as modelling light like you’d be in a photographic studio. Anyone who has done studio photography will immediately know the benefits of this. As you can see how the light is falling onto your model you already know approximately how the captured image will look. With an “old-school” underwater strobe gun you will be using a separate torch-like light source, which will illuminate the target area but has nothing to do with how to image will eventually look once the strobe has fired.

    Photographic tests

    How powerful is 8000-lumens as a flash? Can it compare to an output of a small compact flash unit like the Inon-2000? I had no idea what it could be in comparison with a guide number, which is a traditional measure for flash units.  A few test shots were needed. Luckily my new model agreed to stay still for the following images. (no nudibranchs were harmed during these tests)

    Weefine Smart Focus 6000 test 1

    The first pair of images shows that when you are close-by the Weefine Smart Focus 6000 works almost identically to the Inon. The ISO of the camera was set to 200 and aperture to f/14. The only real difference is the flatter looking beam from the S-2000 as it was used with its diffusor. The Smart Focus 6000 is firing in full power here (setting 9), whereas the Inon is using automatically selected low power setting.

    Weefine Smart Focus 6000 test 1

    The second pair shows what you can do with the Weefine Smart Focus from about a meter way in full power. I had to open the aperture to f/6.3 to get a decent exposure. I can feel the Inon S-2000 firing with much more intensity now, but it still copes well with the distance.

    Weefine Smart Focus 6000 test 3

    For the last pair, I wanted to show the limit of what the Smart Focus can do. A meter away, my camera lens in f16, the Inon S-2000 is discharging fully to achieve a usable, albeit bit underexposed image. Here’s where the Weefine Smart Focus can’t compete anymore. The output is just not up to lighting the frame with a small aperture like that.

    As you can see the 8000-lumen led flash is not as powerful as the Inon S-2000 with its guide no 20. You can forget the Smart Focus 6000 as a light source for wide-angle photography. However, for close-up photos, it works extremely well. In a typical UW macro photo situation your lights are going to be 10-20 cm away from the target, sometimes even closer. For macro photography, you never really use the full power of a flashgun. It ends up usually firing at 1/8th or even 1/16th of the full power. 

    Before you run to replace your xenon-based flashguns with LED flash there are few things to consider. Most current underwater flash units offer some sort of automatic functions via the fibre optic cable; namely the S-TTL function. The Smart Focus 6000 will work only in manual. But if you are accustomed using your flashes in manual mode then there is no difference, apart from one little detail. When using a traditional flash tube the aperture is the key, as the blink of the light will always be faster than your shutter speed. Hence shutter speed changes do not affect the foreground exposure. The LED flash, however, is slower so the shutter speeds matter. Although a fast blink, it most probably is on longer than your shutter opening time, and the exposure can be altered with the shutter speed setting also. If you are used to the idea of aperture-based flash photography this might take while to sink in. Basically, your shutter speed will become the speed of the flash… if that makes any sense.

    Weefine Smart Focus 6000 in a nut-shell

    The Smart Focus 6000 light is one of the most compact 6000-lumen video lights on the market. It weighs only 570g with the supplied Li-ion battery (220g underwater). It is not much larger than the Inon S-2000 strobe unit used in this comparison test. On top of the main beam and the flash functionality, it works as a spotting light with all its different modes: the white, red and blue. In this mode, it will shut itself off when it recognizes a flash being fired. You can also use it with the Weefine’s remote control system via a standard fibre optic cable. The light ships with 1” ball mount, a YS mount and a handy carry case. At the time of writing the Smart Focus 6000 also comes with a light condensing lens that allows you to achieve more dynamic lighting effects. All of this cost £669.00 and considering what is packaged into this small unit that is an absolute bargain.

    Weefine Smart Focus 6000 and Inon S-2000 side by side

    Final words

    The idea of LED flash is not completely novel of course. Most of us have already used one as 99% of current smartphones come with it. It is that small yellow blob next to your camera lens that never seems to give enough light in a party. The Weefine’s LED array is a different kind of beast! It truly provides a lot of light. Although it can’t yet compete with a flashgun, I can see that maybe this emerging technology will one day make the xenon flash tube obsolete… you know like what digital photography did to film. Maybe soon you have a light with 20000-lumen flash function or more. Not sure there is an upper limit really. If you read this article and in ten years’ time flash tubes are gone, you can say where you read about it first 😊

    Find more info and pictures about the Weefine Smart Focus 6000 HERE