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

Unboxing the Knog Qudos action video light

As an amateur underwater videographer, i have to deal with the loss of colours when i do my shootings. The deeper i go, the more blueish/greenish my recording becomes – more water to absorve the energy from the lightwaves, making less available lightwave spectrum. There are ways to compensate this, with filters, using the cameras white balance, or lights.

When i dive, i usually take my gopro 3 silver with me, for some casual shooting of whatever i can see down the water column. I like to keep things simple, and i don´t need professional level filmings, just some decent and neat ones.

Depending on the water turbidity and available sunlight, the gopro fairs relatively well up to around 5-8 meters, with even the possibility of some colour correction in post-production ( i use the gopro studio ). But the small size of the sensor on this type of cameras becomes the limiting factor for capturing light – the sensor just doesn´t have enough size to capture the lightwaves in low light situations, independently the sensor quality and technology. I used a polar pro red filter with the gopro, and the colour in the filmings improved dramacticly – well, at least until i reached 10-15 meters. Unfortunately i broke the filter when i dove in the caribbean sea a while back, so i searched for other solutions.

Enter rhe Knog Qudos. What the heck is a knog, you might ask? Knog is an Australian company, founded in 2003, wich specializes in video lights and bicycle acessories. Qudos is an small form-factor, multi-purpose action video light designed for divers, or nocturnal surfers / riders. It can be fitted to action cameras compatible with gopro mounts, or the coldshoe of dslr´s.

Here are the specifications :

• OUTPUT : 70 – 400 lumens
• DIMENSIONS : 31x70x40mm
• WEIGHT : 150 gr
• MATERIALS : die cast + CNC machined aluminium heat sink and and optical grade lens;
• LEDS: 3 XB-D CREE LEDS.
• BATTERY SPEC: 3-7V 1000mAh 3.7Wh. Replaceable USB Rechargeable Lithium Polymer battery.
• CHARGE TIME: 5-6 Hours
• CONSTANT CURRENT DRIVE TECHNOLOGY: prevents video flicker;
• WATERPROOF : up to 40 meters.

Ligh Modes	Beam angle	Lumens (High/low modes)	Runtime
Action Sports	Wide	High : 400	70 minutes
		Low : 225	1 hour and 30 minutes
Target Spot	Near	High : 175	1 hour and 50 minutes
		Low : 100	2 hours and 40 minutes
Ambient	Ultra wide	High : 270	1 hour and 10 minutes
		Low : 70	4 hours and 30 minutes

Pricing : can range from 80 to 100 euros.

So let´s get this bad boy out of it´s cage.

 

First, the packaging : it comes with a metal sheet case, cool, but too thin, it kinks real easy. The case has a lid that´s on the back. Very nice, with a premium look to it.

 

The acessories included inside : action Camera Mount Bracket and Hardware, Cold Shoe/Tripod Adaptor (for use with DSLR cameras), USB Recharge Cable, two silicone anti-vibration pads, two stickers, a quick reference card, and a spare o-ring.

 

 

The 3 Leds : all three are one when in action sport mode; only the bottom one in target mode; and the top two in ambient mode.

Opening the plastic backdoor gives acess to the battery. The door is not very tough, but the locking mechanism is tight, and won´t open accidently. Below the locking mechanism there are 4 led lights, The first 3 from the left indicate what is the current light mode selecter. Each light mode has 2 colours to indicate high ( green ) and low ( blue ). The forth led is the battery charge level.

Unlocking the backdoor.

 The battery is removable, and charged via usb or charger. It has indicator light on the battery, so you now when it´s fully charged..

 

This is the setup i´ll be testing the light : a SP pole and the qudos. Simple, and portable. I made a small modification so the camera won´t scratch the side of the light, and also keep it in place - i cut the small silicone anti-vibration in half, and put it between the two.

Next article, i´ll post in-water testing with this setup.

Thanks for the attention.

Atlantic Diver