An important choice has to be made before buying a dive light: Do I prefer a spot light or rather a broad angle video light? Most dive lights available on the market at present only feature one of those functions. In the following guide, we want to further explain these functions and give advice of how to make good use of them.
In order to understand the principles of spot and video lights, it is important to know the difference between Lux and Lumen, explained in our previous blog entry [here].
What types of dive lights are available?
When it comes to dive lights, there is a distinction between several types: primary light, back-up light, and the photo and video light. Some lights are able to combine those functions and can therefore be placed into more than one group.
Primary dive light
The primary dive light is mainly used to communicate with the diving buddy under water. With the aide of light signs, one may point out possible hazards to the partner or draw attention to oneself. The dive light is then used as a classic pointer. Dive lights of high quality have a bright, highly focused and distinct spot. The illumination intensity should be around 30.000 Lux in order to ensure good visibility while competing with the sunlight. The focusing should be 8° or less at full angle. A light with a well focused spot may reach the same illumination intensity at approximately 1.000 Lumen.
(The indication full angle refers to the actual angle of the light cone. Some manufacturers only specify the half angle, in order to be able to advertise with lower = better values.)
Besides a tightly focused spot, a good primary light should also illuminate its surroundings. The less illuminated area around the spot is known as the corona, which increases the field of view. Most divers prefer a continuous decrease in brightness towards the borders of the light cone. Typical values of a corona are 500 Lux and 60° to 90° full angle. The greater the angle of illumination, the better the orientation, since the visual awareness is not only reduced to what is in front then, but also further extended to the top and below. The human eye has a field of view of about 130° to 180°.
In general, the Backup light should meet the same expectations as the primary light. However, less luminosity is fine as the back up light is only used in case the primary light got lost or isn’t working anymore due to technical defects or empty batteries
The most important property of a photo and video light is its Lumen output. The more Lumen, the brighter the picture. For the average and simple video recordings, 2.000 Lumen should be enough, while professional video lights usually begin with about 5.000 Lumen. Due to the large scale light distribution, the reached light intensity is between 1.000 to 3.000 Lux. Not only the amount of light, but also the color temperature and the color reproduction index (CRI) are of great importance. Color temperature may vary from 2.800K of a light bulb to a heavy bluish light of some LED’s with 7000K. Video lights with about 5.000K are mostly used for under water video recordings, since that value is close to that of the daylight. The color temperature and the color reproduction index (CRI) are explained in a separate blog entry.
Only a few lights combine the functions of both a primary and a video light. It is not unusual then that compromises have to be made in terms of light output, size or weight. The SCALEO infinity is the first dive light that features a full-featured primary light along with a full-featured video light, combined in a robust casing.
What influence is exerted by the water I dive in?
Both broad angle video lights and spot lights can be used to full extend in clear waters. If the sight is hindered by floating particles though, it is recommended to renounce the broad angle light, since the resulting effects are similar to that of a high beam on a foggy day. Most dive lights have only one single light source and the relation between broad angle light and spot is generated by the shape of the lens. The SCALEO infinity is equipped with two independent and continuously adjustable light sources. That way it is made possible to ideally adjust the light to the current environmental condition, for example in cloudy waters one may want to turn off the broad angle light completely, or turn off the spot in order to use the broad angle light for photo and video recording. Finally, any combination in between may be chosen to accommodate for the present needs of the individual situation.