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This is a very common question, that has become increasingly relevant as LED technology improves every year – can I use LED video (continuous) lights to shoot photos instead of using strobes?
If you asked this question several years ago, the answer would be a clear no.
However, as LED’s become smaller, more efficient, more powerful and more affordable, the more capable it becomes to illuminate your underwater photos.
To compare the two, it’s important to understand the lumen equivalent of a strobe. The way a strobe and a video light emit light is different, so you cannot directly compare lumens to Guide Number. However, it’s safe to say that an entry level video light with 20GN, emits a light roughly equivalent to a 40,000 lumen light, when shooting at a common shutter speed of 1/125s.
Given that as of 2019, most consumer video lights which sell for the same price as strobes, range from 3000-5000 lumens, you won’t see them replacing strobes any time soon.
The main difference, in which strobes will always have the advantage (until technology allows otherwise), is that the strobe emits most of its light within a fraction of a second (about 1/1000s on full power), which effectively freezes even a very fast moving subject. The actual shutter speed you use, as long as it’s within the maximum flash sync speed (usually 1/250s in most DSLR’s and 1/160s in some mirrorless cameras), has no effect on the amount of light emitted. This helps you separate between the ambient light exposure and the strobe light exposure making it easy to balance the two. That balance by the way, is the key to great underwater images.
On the other hand, a continuous light requires a slower shutter speed to be used so that the light will “have time” to show up in the photo. It has to be sufficiently strong to maintain a faster shutter speed for freezing the subject and lowering the exposure on the ambient light.
All of that being said, there are many advantages to using a continuous light, especially when it’s strong enough for what you need, such as night dives or macro / close up shots:
- You can use burst shooting without waiting for the light to recycle.
- The light is always on, showing you exactly how much light falls on the subject and how it’s distributed.
- You don’t need an additional focus light, the light itself helps the camera focus
Today there are some video lights that can output a strong “burst” of light, similar to a strobe, only it lasts about 1 second instead of 1/1000s and it usually increases the output by about 1.5. So technology is getting there, but it’s not quite there yet.
Read more about underwater strobes
Read more about underwater video lights
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