The bullet light – BossK BigBlue LED focus light with AFO

image If you are a super dive geek you will already have noticed the BigBlue AFO lights look just like the underwater TV camera mounted on the bottom of Mike Nelson’s boat in some of the Sea Hunt episodes. The shape of this light is so eye catching that, even though all but a few of the lights made by Hong Kong based BigBlue (BOSSK International) are NOT bullet shaped, divers mostly associate BigBlue as the company with the bullet shaped light. Here we review and report on our extensive live testing of the Big Blue FF 1×5 W AFO light (1 5 watt LED).   

Why a focus light?

All digital cameras and many film cameras use auto focus. Before you take the photo, the sensors in these camera need to clearly be able to “see” and register the object you want in focus, then adjust your settings. It is very common underwater that you will not have enough ambient light for the camera to get an accurate fix on the exact spot you want to feature in your image. A separate focus light can illuminate the image and vastly improve your chances of getting a sharp image. You could use any small dive light, but there are significant downsides over using a dedicated light built for this purpose. A true focus light will have different features that make if perfect for focusing (but not so good as a regular dive light). The first is Auto Flash Off.

Why you need AFO (Auto Flash Off)?

You want a nice bright light to make sure your camera can focus, but you do not want that extra light over-exposing, or blowing out, your photo or creating a hot spot in the image. AFO lights, like the BigBlue focus lights have a sensor that will pickup the flash from your strobe and instantly turn off the light during the exposure (for 3 seconds in this case). Another advantage of AFO lights is that they can reduce back scatter. If the light stayed on during the exposure it would also illuminate any particles in the water and create backscatter. This would at least partially waste all that money you spent on brackets and arms to make sure your flash does not create the back scatter.

Another feature of the BigBlue dedicated focus light is a wide beam. The 1×5 has a 60 degrees wide angel beam the blankets a wide portion of your image. It also has 6500K white light that reflects true colors.

Live Test

We found this light to be nearly perfect for the job. It is extremely well designed. It lights your scene during composition and allows the automatic focus and other settings sufficient light to do their job. We tested it in the emerald green waters of the Pacific Nortwest at many levels of vis and in the tropical clear waters of the Cayman Islands. It proved its worth through out the whole range of environments. The size and brightness (170 lumnes) seemed just perfect. Some of the smaller and cheaper lights from other companies did not have enough power for the full range of shooting conditions.

This aluminum bullet housing is extremely sturdy. It is unlike other lights with failure prone mechanical switches that pierce the container or those with twist on heads that are easy to twist off enough to leak. We have seen a lot of failures from those other type of lights. The BigBlue’s simple assembly seals tight and we will be surprised if anyone can flood it without trying really hard. It also uses rotary magnetic switch with a wide ring and lock system that is simple to use even if you are wearing polar diving mittens. It is the easiest and most reliable switch system we have seen. The light comes with a detachable ball that mounts it to most camera rigs (see photo). It also included an optional handle that gave the impression that you could use it as a dive light. Sure, in an emergency or in very specific case it could be handy, but the same features that make it a nearly perfect focus light make it a only a minimally useful dive light. The bright wide beam does however work nicely around the house or the walk on the surface at a night dive. Since it is designed to be cooled by the water it has a safety off feature that will protect the electronics from damage if it gets too hot while being used on the surface. We never had this kick in during our land tests.

A Few Minor Issues

BigBlue, as a very innovative company is constantly pushing the design edge and evolving their product to make them better. The one downside to all leading edge companies is that you have to be careful to understand and watch for the features and parts new concepts and “almost” ready for primetime. For example the BigBlue lights that are newer than the one we have, now come with a sleeve around the battery holder to prevent them from dislodging while assembling the light. Not a big problem but BigBlue has already fixed it. However, there is another important issue where an in store inspection can save you a return trip. Because the light was originally designed to have user serviceable parts in the head, the AFO sensor is not permanently fixed in place. Before you pay for the light, make sure to inspect this sensor. As long as it is mostly level and flush with the front plate it will work fine. But if the sensors appears to be set back from the front plate the light will not be reliable in turning off when the strobe flashes. If you run a dive shop selling this light, we recommend you open the boxes and pre-inspect the light to save your customers the trouble. The BigBlue US distributor is happy to replace lights that got past QC with sunken sensors.

We see no reason to let these issues discourage you from purchasing this great light. We are just trying educate divers to be educated consumers. You as the purchaser or dive shop owner should be vigilant when purchasing equipment and check it over before paying. All innovative companies tend to have similar growing pains. Additionally, as we have pointed in other articles, there is a growing problem of “quality fade”, especially with products from China (see With any product, your pickiness will send a message to all manufactures that we divers expect good quality control.

The Bottom Line

Despite a few minor issue to watch for, we still give the Big Blue FF 1x5W AFO Focus Light a full 5 stars because it is sturdy, easy to use and performs perfectly as a focus light. Pricing is a around $150. We also are watching this innovative company for more great lights to come. We are especially looking forward to testing the new CF-250, a 250 lumen pocket light that is focusable and as bright as many primary lights. It may be the killer app of the dive light world.

The Specs from Big Blue for the FF 1x5W AFO Focus Light.

Light source 1 x 5W LED, with optical diffusion lens
Light output 170 lumens
Casing material Anodized, anti-corrosive, aluminum alloye
Colors A choice of different main body colors:
Amber, Emerald, Ruby and Sapphire
Power source 4 AA batteries, Alkaline 1.5V or Ni-MH 1.2V
Angle of light beam 60°
Color temperature 6500K
Light efficiency Equivalent to a 8 watt halogen bulb
Burn time Up to 8 hours
First 3hrs at 100%, second 3hrs at 50%
gradual reduction of output strength until switched off
Maximum depth 100m
Diameter 56mm
Length 206mm
Weight in air 460gr (with batteries)
Weight in seawater 120gr(with batteries)
Switching system Rotary magnetic switch system
Transportation lock Closure system with blocking button
Front glass Tempered optical glass
Thickness 5mm – 41mm diameter
Lanyard Included
Lantern handles Anodized, anti-corrosive, aluminum alloy

more info at: or – Tim Ratcliffe 727-734-8948.

The test light was purchased from in Seattle.

We thank Tim Ratcliffe of BosskUSA/Big Blue for his assistance and quick response to our questions for this article.