THIS YEARS HOT TOPIC AMONG TRAVELLERS is the fact that, however cheap air-travel may be, its not cheap if you have any amount of baggage to check in over and above the allowance.
Member-airlines of IATA can charge 1% of the first-class fare for every kilo in excess. That equates to 10% of the economy fare.
This might not be too painful on a trip to Europe, but once you get into long haul it can be cheaper to buy another ticket and bring a friend (who gets the 20kg allowance) than to be caught with more than 10kg too much.
I have had to rethink my own travel arrangements. I always take a solitary camera in its underwater housing as carry-on, my big heavy German Subtronic flashguns had previously been checked in along with spare kit.
I now simply take a pair of lightweight Japanese-made flashguns that will fit in my carried rucksack.
The Inon Z-240 flash is popular with many well-known British underwater photographers. This could be simply because it is imported by a popular underwater photographer equipment retailer, but then, he used to import Subtronic.
The product certainly looks a bit amateur, because it is made of polycarbonate and has flimsy-looking fittings. A pair weigh around 1kg. The latest incarnation is the Type 3.
I needed to mount the new flashguns on my old flashgun arms, and Inon wisely supplies
a range of optional fittings for this purpose.

Four AA ni-mh batteries, contained within their own watertight compartment, power the unit. They are protected by a screw-down cap and a big O-ring.
You need to ensure that this O-ring is lubricated and does not twist as the cap bears down, or new batteries will be needed. The cap allows visual inspection of this. Inon specifies Eneloop batteries, though the reason is unclear.

The Inon uses two small flash tubes at right angles to each other. This is said to give an even-lighting effect, but I found it too sharp, so elected to fit the 0.5 stop diffuser supplied.
There is also the option of a 1.5 stop diffuser, which will be more useful to owners of compact digital cameras that do not have the facility to set a small lens opening when doing close-ups. The lighting effect is the same, but less light is emitted.
The diffuser fits neatly, using one thumbscrew, and allows the built-in focusing light to shine through a hole. I would say that a diffuser is essential when using a wide-angle lens or fish-eye.

The instruction booklet is very comprehensive, and quite daunting, because the Inon flash is a marvel of electronic technology that comes at the price of complexity.
Let your dealer set up your flashgun to suit your camera, or visit index.phpaction=kb&article=7, where you will find a good explanation of the controls.
You need to establish the synchronising protocol for your digital camera (easily done, as you can instantly see the result) and once set you never need to reset it.
It accommodates synchronising with a pre-flashing on-board camera flash, but will trigger when the picture-taking flash fires.
I deactivated the advanced circuit switch and synchronised the main flash with my camera via a Sea & Sea synchro cord (not supplied). I used a second synchro cord via a Sea & Sea junction.
However, to limit the number of O-ring-protected connections, what I should have done was use a single cord and let the second flash be triggered by its photocell slave.
A blanking cap to stop it being triggered by the flashes of other photographers otherwise covers this. The importer has since sent me a blanking cap with a directional hole cut in it, and I just have to be sure that it faces the main flash to function properly.
The other way is to use a fibre-optic cable, and the flashguns are fitted to accept this.

A separate control allows you to choose whether you want STTL (also an option of low-output mode), auto exposure, TTL for Nikonos, variable manual or full power.
Although the electronics allow you to choose a setting that will dovetail neatly with the protocols of your digital camera, as I was using a semi-professional digital Nikon camera I used the Z-240 in manual mode.
You can set it to full power or set it to one of more than a dozen power settings.
A lot of the electronic features depend on the camera. If you find that it continually over-exposes with your compact, you can turn down the power setting, which it remembers and automatically adjusts to suit.
You can also set the LED focusing light to stay on, stay on for eight seconds, be off, or come on as soon as the flash has recycled, ready to go off when the camera release is pressed, so that there is no trace of it in your pictures.
A blue filter is supplied to match the light of this focus light to the flash, and a red filter is included for use when photographing macro subjects that might otherwise be disturbed by the light.

The light seemed similar to that produced by the Subtronic, and I put this down in part to the diffuser. The colour was the same as sunlight.
Recycling time between flashes at full power was rapid. The book says 1.7sec, and I rarely missed a shot when working quickly.
I found that I did not need to recharge the batteries before I had completed three dives - and that would be after, say, 180 exposures. The book promises 200 exposures with fully charged 2000mAH ni-mh batteries, or as many as 380 with lithium-ion. That meant that I needed to open the flashguns only each evening.
The two units produced less light than I was used to, but with a digital camera one simply ups the ISO setting to compensate.
With wide-angle pictures I was habitually using f/8 at ISO 200. With macro set-ups, I could use stops as small as f/22.
With three trips to the Far East and Australia so far this year, the cost of these flashguns has already been met by the excess-baggage charges saved. One Inon Z-240 costs 565, plus synch lead and mounting arm.

Ikelite DS125, £510
Sea & Sea YS110, £300
Sea & Sea YS250 Pro, £630

Divernet Divernet
BATTERIES 4 AA rechargeable
ACCESSORIES 1.5 and 0.5 diffusers
NOT INCLUDED Sea & Sea synchro lead. Mounting arm.
GUIDE NO (ISO 100) 24/metres
DIVER GUIDE width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100%