My Vivitar 285 flashes over 4oo times instead of only 60.Take a six volt motorcycle battery, a block of wood and about four feet of wire, a couple of clips and Hey Presto, an external battery pack at a total cost of less than £30.
I successfully carried out similar adaptions to three of my caving flashguns back in the seventies, plus three video cameras during the nineties so I guess it follows suit that now it's the turn of my digital lighting equipment to be, shall we say personalised via a little cheap DIY.
I think the most complicated part was soldering the mid-wire joint together - these are commonly used for radio controlled car power leads as they are capable of carrying plenty of current, yet are quickly detachable in the event of smoke emerging that very first time you connect up your delicate electronics.Be Very Careful to get the polarity correct and use a multimeter frequently during this build.
I went to Maplins for the electrical bits such as a Maplin six volt - 4.2amp battery at £9-99, charger at £11-99, twin wire, HF10L spade terminals and FE65V plastic teminal covers, a two part snap joint with part numbers GZ99 and JG05 = £30 the lot.
Incidental extras consisted of block of wood, two pan-head screws, a soldering iron, saw, screwdriver - all of which I found in my shed.
As with any alterations to any photo equipment the warranty becomes void
if you go tampering within the guarantee period - that said then go for it!First off you have to figure out which are the positive and the negative contacts inside the battery compartment. Two of them merely carry the power from one battery to another and will show a dead short when both are touched with the two multimeter probes.
Set the multimeter on Ohms for this test and a reading of zero means there's a dead short, or a figure one in the digital display means open circuit, any other reading means there is something electrical or electronic component between the probes.If you're new to the use of a multimeter try testing a 100 watt household light bulb. First off try touching the two probes together and you'll get a reading of zero. Now touch the two blobs on the base of your bulb and you'll get a reading of approximately forty ohms as the filament is acting as a resistor between one terminal to the other, (think electric fire bar glowing red, that is one heck of a resistor, meanwhile the bulb filament glows white hot).
Let's test the terminals inside your flashgun. If it's a Vivitar 285HV like mine the two terminals closest to the front are linked and this shows up pretty clearly via bright shiny metal. The other pair of contacts are what carries the battery current into the flash unit, but which is neg and which is positive? The answer is to look at the battery assembly where each battery is clearly marked with a + sign, it's the pointy end. Of course most other flashguns have neg / pos diagrams marked in white paint inside the battery compartment.
Right, grab a piece of wood and make it the same size and shape as the interior of your battery compartment. For a Vivitar it's rounded on three corners and square on the fourth corner. There's a saw blade width groove running down one face of your block which will slide over the protruding plastic down the front facing side of the battery compartment.Fit two screws into the end of the wooden block which will be carrying your external power supply. These go towards the rear face of the compartment with positive terminal closest to the hotshoe. Check the polarity with a multimeter before inserting it that first time!
Go to either the battery assembly, or the battery + markings to figure out which screw on your wooden block is going to be positive.The length of wire for my setup has been kept long enough for the flash to be 8 feet up on a lighting stand and the battery on the floor, this way it can't fall any further and risk damage to my rather marvelous 285HV flashgun.
You can either leave the battery door open a little to allow entry of the wire or, for if yours is the hinged sort, file / drill a hole on the door edge. To facilitate this entry point you will have to drill a hole for the wire right down through the wooden block at an angle, from one edge nearest the door catch down to the centre being careful avoid the screws.
Recycling time for the flash on full power remains at 7 seconds for a couple hundred flashes and very gradually drops towards 15 seconds over the next two hundred. Compared to normal AA batteries this is a Godsend, a whole wedding without waiting an eternity for the damned flash to recycle!
One of these pictures shows a caving battery belt, actually an old car seatbelt on which I used for abseiling, caving and to carry a twelve volt burglar alarm battery for video cameras, (I try to save money where possible, but I must try to go get hold of one of those lightweight gardening belts for this flash battery setup).
The wide metal plate belt loop in the same shot is so I can be totally portable with my Vivitar 285HV and my DIY brolly bracket, (see a previous post for those details).
Before, with AA batteries, I was waiting thirty five seconds within twenty full power flashes and a whole minute after fifty flashes!
I do tend to use the Vivitar flashgun on 1/4 power for brolly photography and recycling time is just two seconds. Without the brolly I'd be using 1/16th power which means recycling time is virtually instant. I am far more than happy with this little bit of DIY.
