Knog Qudos action video light - First impressions, considerations, and tips

The first real-world test of the pole-knog tray + light has been done finally. Conditions were far from optimal, so we can see how good it handles it´s function in low visibility dives.

The test was conducted with the gopro 3 silver, recording at 1980x1020, 30 fps, medium view mode. The dive site chosen was River Popa, the stern of a cargo ship that broke off after it collided with the walls of cape Espichel, in Sesimbra, Portugal, around 15 years ago. The average depth during the dive was 20 meters, with a bottom time of 35 minutes on air, and the visibility was around 5-6 meters, with alot of suspension near the bottom.

First of all, this tray setup, as highlighted in the qudos instruction sheet, is not recommended for scuba diving, as the closeness of the light source to the lens will cause alot of backscatter ( basically it lights up suspension particles in front of the lens, as we will see ), reducing the quality of the shots. This first run confirms this, even shooting in medium view. Knog recommends the qudos to be used in a dedicated dive tray.

Fiddling loosely with the lights three modes, we found that action mode, the brightest one, can be used to light up large overhead enviroments, like caves, or the inside of the ship´s hull. But even in it´s low settings, it causes either to "burn in" the subject in the image ( like a fish ), or light up backscatter in a panoramic shot. Perhaps this can be mitigated if the light source is moved further away from the lens ( knog recommends 50 cm! ), but this set-up is about being practicle, not optimal.

The second mode, spot mode, perhaps is more usefull for macro or night diving, as the light beam only illuminates a subject, and not the surroundings. As the beam is narrower, it causes less backscatter.

The third mode, ambient mode, is what perhaps seems to be the most usefull. The light intensity is just right to shoot close subjects, and even some more distant shots, and it´s a good compromise in relation to other modes, as it saves battery and provides good overall lighting.

Battery life was as expected, lasting the hole dive always on, sometimes in the maximum setting, but mostly with the ambient light setting. By the end of the dive, the battery indicator signaled low battery, but the light didn´t fade, and i thought it could carry on a bit more. As a primary light source, i can´t recommend it, as i think the user has to be conservative and turn off the light after shooting, or it risks running out of battery by the end of the dive. Anyway, the user will need to recharge or replace the battery after every dive, or be extremely conservative on it´s use. On the positive side, as it´s charged by usb, a power bank might help in recharging the battery.

Perhaps Knog could provide a bigger capacity battery on the future.

On the next time, we will change the position of the qudos on the tray, placing it on the right side of the tray, with a little hacking, to put it a bit more away from the lens, in hope it will reduce backscatter.

Stay tuned.

Atlantic Diver