This group seems free-wheeling enough that you might enjoy hearing what I have been working on for two days (although I will likely bore some of you into hitting the trash can icon). It is a stage prop made using the guts of a Vivitar 283 flash.
Before any of you start screaming and cussing at me for cannibalizing a 283, hear me out. This play needed a prop consisting of a small metal bowl on the end of a short pole, with a strobe lamp inside the bowl rigged so that it would fire when the actor pushes a button on the side of the pole. The metal bowl will reflect the light outwards and upwards. One of the adults (this is a local children's theatre company) asked at the only electronic parts distributor left in town (30 years ago we had four distributors plus several Radio Shacks) if they could do the job. They said that they could not, but suggested that they call me. I told them to see if they could get someone to donate some old camera flash units for the project. An out-of-town friend of one of the adults donated three Vivitar 283 flashes, all rather sad looking, all missing their light sensors, two missing their battery holders, and one even missing its hot shoe. Next comes some technical explanation that should be familiar to us senior citizens but may be new information to the young folks in the group. I expect that some of you have used a Vivitar 283. The original 283 from the late '70s and early '80s was one of the seven wonders of the world of photography with automatically controlled flash duration (controlled by the light sensor). Even one in top condition today would be useless with most DSLRs. Old-school film SLRs triggered the hot shoe by closing a switch connected to the shutter button. Flashes of the day put 200-300 volts on the hot shoe, needing a relatively stout switch to trigger them. That also meant that if you were stupid enough to pull the flash off the SLR without discharging it you could get a nasty shock from the flash. In any case the 283 does not support TTL (through-the-lens) flash control they way that the better current speedlights do. Today's DSLRs are generally designed for a much lower trigger voltage in the 5 to 24 volt range. Some models of DSLR may be able to handle trigger voltages up to 250 volts, but you had better be darn sure that yours will before tying to use a 30-40 year old flash, as many cameras can sustain electronic damage if you try to make them handle 200-300 volts on the hot shoe. All in all those three donated 283s are useless for current use unless you are using an old-school 35mm SLR, and even then none would control the flash automatically since all three are missing the light sensors. It took me an entire working day yesterday to 1) show that all three properly worked in manual mode (fortunately I had one battery holder), 2) find and download the service manual (well worth the $4.99 I paid) and read it thoroughly to familiarize myself with the circuitry (it is a complex beast), 3) go out and buy some parts and components that I needed, and 4) do most of the disassembly of my candidate, the saddest looking one which was missing the hot shoe. Today I finished the disassembly and started removing bits and pieces that I don't need, such as the automatic flash duration control circuit and other gewgaws (if they had room they would probably have included a kitchen sink in the design). I have been building the prop with some parts from my extensive electronic scrapyard (I've been collecting electronics of various sorts for nearly sixty years), a couple of parts bought at the electronic parts distributor, and some physical components from the home center. I expect to have it ready to demonstrate at tomorrow afternoon's rehearsal. It will not be in finished form - it will be in what we radio engineers formally call "proof of concept" stage. It will be ugly but will demonstrate how well it works. Informally some call that the "chewing gum and paper clip stage," or as I prefer to call it, the "baling wire and duct tape" stage. Note that tomorrow some parts will, in fact, be held together with duct tape (but probably no baling wire). It will be in its final aesthetically pleasing form in time for the first dress rehearsal in a couple of weeks. My total investment will be about twenty hours of labor. At my going labor rate for my most favored customers (I still work a little for some small locally owned radio stations) that would amount to 10 Benjamins, and I am donating the labor. The out-of-pocket cost for parts and materials is another matter as they have no budget. Fortunately they have three of those Vivitar 283s, so they will have a complete parts junker to keep the prop working and I will get one as compensation for my out of pocket expenses. I will modify it for a much lower contemporary trigger voltage (so I won't fry one of my wireless triggers). The missing light sensor is no problem as I will add a control to manually set the flash duration and I will use it as an off-camera flash for fill or highlighting. It is a 2900 BCPS 5500 Kelvin unit which should work well for me as a supplementary flash, and my mod will allow me to manually select flash duration from 1/1000 to 1/30,000 of a second. Dale H. Cook, 50+ years as an SLR photographer, Pentax K-70 w/ Pentax-DA 18-270mm lens, using colored filters for B&W gravestone photography -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
