Focus Light


Focus lights are used underwater to air lenses to auto focus under low light conditions ofter found in the marine environment. many camera lenses are not fast enough to have good auto focusing in low light or with subjects that adsorb light.

There are many different lighting options for focus lighting and just as many ways to attach them to your camera. Not all work easily and can be  frustrating if you need to work quickly. Some strobes like the Ikelite DS 160 and DS 161 have built-in focus lights and makes it easy to use. Some lights have spot beam (very narrow coverage) and others some what wider coverage. Form macro lenses wide coverage is not necessarily needed.

Light and Motion Sola 800 focus light

Sola 800


This is the best focus light I have ever used!

The Sola 800 photo light from Light & Motion is the latest upgrade to the revolutionary SOLA lights.  Simply better  and still half the size of the competition, it produces more light than any focus light in its price range. Its wide flood doubles as a general video light for the new classes of camera with video capability and the red light lets you sneak up on the skittish creatures.

Lumens (White / Red): High- 800 / 22 Med- 400 / 113 Low- 200 / 57
Run Time (Min): High- 65 Med- 130Low- 260
Charge Time: 150 Minutes
System Weight: 283 gr w Ball Mount
Size: 57mm x 101mm

Sola 800 light Features:
•    3 levels of broad, 60 degree white light, 3 levels of red
•    65, 130, and 260 minutes of burn time respectively on the 3 power settings
•    Tiny and light, only 283 grams, 57mm x 101mm in size

Sola 800 CHARGER
The Sola 800 photo lights have a factory sealed body so you never need to worry about flooding. Control is accomplished through a magnetic tap switch that allows quick power changes and locks for travel.  Three indicator lights behind the bezel report the power and battery charge status.
Included 1″ ball mount allows you to mount your dive light on your SLR rig and use with Ultralight arms.
Optional Wrist mount offers comfortable neoprene padded molded plate with locking light release and adjustable straps. “D” ring on light offers alternative BC or wrist clip option.

Here are some examples for mounting focus lenses to a SLR housing.

Sola 800 focus light










Ultralight makes enough light mounting fixtures to mount just about any light for focusing and for video.

Ultralight mounts and cradles.

Nexus has a PORT STAY for their system

The real problem is choosing the right one for your needs. Some lights are so bright that their unwanted light will show up in your exposure. Others are to dime to work all the time. Some are bigger than your camera housings.

They all use batteries and this presents the need for additional care and maintenance. Some lights use AAA size and can be re-charged. Others have dedicated batteries that cannot be removed putting the light out of commission until they are charged. Some can be used as video light but usually cost more than you camera.

Focus Light Testing by Lee Peterson   This is a PDF file.

We dive and try all kind of lights. Please give us a call so we can get you the right light for your camera system and save you time and money. 858-481-0604.  Or email us at

Your batteries are probably the most critical element in your entire digital camera equipment kit. Choose the wrong batteries, and you can be left with a camera that’s no more than an expensive paperweight when that once-in-a-lifetime shot appears. Changing batteries underwater is not possible. Your dive depends on batteries that don’t quit when you need them the most. Although there’s no issue of which brand and type of batteries to buy, just be sure to get an extra battery pack or extra set of back-up batteries and keep them charged as a spare set. Most digital cameras use conventional AA-size batteries, which opens Pandora’s box of potential battery issues. Some have proprietary lithium batteries, but you have to make sure you have fresh extras with you. Your batteries have to handle the constant-power loads that most digital cameras require. When batteries are used in a camera (and their terminal voltage drops), the camera draws proportionately more current from them. This is a bit harder on the AA-equipped batteries for cameras. It’s well established that standard alkaline batteries are almost completely worthless and cost more to use than good rechargeable batteries. A big problem with batteries that are under a constant load is HEAT. Hot batteries lose capacity and give off heat. This heat build-up in a closed underwater housing can effect the camera’s operation. Digital cameras do not like heat. Your instruction manual will tell you that optimum operating temperature is 50F to 75F degrees. Operating your camera at temperatures beyond these values can adversely affect your picture quality. Also, hot batteries expand in size and may be difficult to remove from the camera while they are warm. Batteries with larger capacities tend to expand more.

How are batteries rated?  Most of us are accustomed to seeing batteries rated in milliampere-hours (mAh), (other than Alkaline that are rated in Volts) as measure of how much current they can provide over time. A rating of 1600 mAh means that the battery should theoretically be able to supply 1600 milliamps (mA) for one hour, or 160 milliamps for ten hours, at an ambient temperature of 65F., etc. The best NiMH AA cells today carry ratings of 1400 to 2200 mAh and mAh is really only part of the story. What you should be concerned about is how much total energy a battery can deliver. Energy is measured in Watt-hours, the product of voltage and current over time, or volts times amperes, measured over hours. (A milliamp is 1/1000 of an ampere.)?Your digital camera requires constant voltage when it is turned on. The internal flash will require additional voltage when it recharges after the flash is used. To measure total energy, it is necessary to measure the voltage and current moment by moment throughout the battery’s discharge, multiply the two values together, and total up all the individual readings. The total run time will be an approximate indicator of energy capacity. Some batteries will run shorter periods of time but deliver more energy than ones with longer run times. It is possible that the measured mAh capacities of the batteries won’t correlate perfectly with total energy capacity. Rechargeable lithium-ion battery can discharge rapidly making them good for fast recycle times but they are very dangerous if they are shorted out and can cause fire or damage to your equipment.

Watt-Hours are what really count. There’s a lot of advertising about mAh ratings, but even the standard way of measuring mAh will give optimistic values when compared to what the batteries actually deliver in typical camera usage. Just because the battery has the big NiMH numbers on its side doesn’t mean the battery performs at that rating. The problem is that digital cameras use a lot of power, which translates into a lot of batteries. Batteries are much less efficient when driving consistent heavy loads rather than light ones. Manufacturer’s test and report their batteries’ capacities according to the industry standard and the results may have little to do with how well the batteries perform in a real-world usage using digital cameras and accessories.

The Importance of the Charger  One of the most interesting things is that a charger can make a huge difference in the charging capacity of your battery! The worst chargers (in terms of completeness-of-charge) will produce “charged” battery with only half the stored energy of ones charged with the best chargers. No matter how good your battery is your charger is the most important companion.

Trickle-charger versus rapid charger: For topping-off and charge maintenance, a charger must be able to do both. This combination is also the gentlest on the batteries. Rapid charging heats up the battery and the charge is never completely full. Trickle (slow, 8 hrs or more) charging avoids the heat problem and the battery has a much better chance of getting a full charge. Battery performance is very dependent on the charger used. Having the best batteries in the world won’t do you any good if you’ve got a lousy charger.

Battery cost isn’t terribly relevant for digital camera usage:  Spending $4-5 more for a set of batteries for your $800 camera makes sense if it’ll net you an extra 10% run time, time after time. One missed picture would easily erase any benefit the cheaper batteries offer.  Some chargers charge batteries in series. This means if one battery has a problem with charging due to high internal resistance all the rest of the batteries will be charged to the rate of the lowest capacity battery. It is good to avoid this kind of a charger. Get a parallel style charger that independently charges each battery according to its needs and will have an individual indicator light for each battery to let you know when the charging is complete. Then you will know that each battery is correctly charged and you will get the maximum use from them.

As you may be aware certain consignments containing Lithium Metal and Lithium Ion Batteries being sent by air freight now require a caution label to be attached. As a result of several serious incidents, the 50th edition of the IATA Dangerous Goods Regulations (Effective 1 January 2009) documents significant changes in regards to the safe transport of Lithium Metal and Lithium Ion Batteries/Cells by air freight.

Lithium chemistry batteries have been with us since the early 1990s. They pack lots of power for their weight and size, have no memory effect, and are lighter than older nickel metal hydride batteries. They are also potentially dangerous when mishandled, abused or incorrectly manufactured. The lithium used in these batteries is a highly reactive element which can ignite when exposed to high altitudes in its pure form. Intense heat or physical damage can rupture lithium battery cells causing fire or explosion.

The average rechargeable lithium-ion battery is created by packing cells the size of AA batteries with about 0.6 grams of lithium. When you put these cells into groups of 4 to 12 and arrange them in a plastic housing, you get your typical laptop battery or battery pack. These packs have a lithium content ranging from 2.4 grams to 7.2 grams. The maximum “safe limit” for shipping is 1 gram per cell and no more than 8 total grams of lithium per one battery. Each battery is made safe for normal every day use by installing special chips or circuits that normally prevent over heating, short circuits or over voltage; all of which could cause combustion.


Getting rid of old batteries is a problem. I save them in special chambered plastic boxes and tape the ends to prevent discharging. Locally I have to drive about 10 miles to a battery recycle center to dispose of them. I wait until I have a 1 lb of them and them drop them off. It is now against the LAW to put used batteries in the trash. Also, not good for the environment if you care about that. We all have to be somewhat responsible for our life style in the community and it is a good idea to find out where you can dispose of your batteries.  Here is some more info on this issue. If you find a good solution let me know.

©Lee Peterson 2011 All rights Reserved.

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