[rollei_list] Re: Rolleiflash Disaster

  • From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
  • To: <rollei_list@xxxxxxxxxxxxx>
  • Date: Mon, 7 Dec 2009 17:50:08 -0800


----- Original Message ----- From: <aghalide@xxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Monday, December 07, 2009 4:49 PM
Subject: [rollei_list] Re: Rolleiflash Disaster


Harold Edgerton used flash to produce a stroboscopic effect. He was famous for his high-speed stop action photos. The high-speed photography was instantaneous. Flash bulbs are not instantaneous. They require what was called m or f synchronization. Camera shutters used to offer either x for instantaneous for electronic flash, or m or f delay which represented the time between when the shutter was fired and when the flash went off. You have the possibility of 3 delays for the flash when you click the shutter on older cameras. Only x has been retained, and they don't even call it x.

Ed Farber brought the electronic flash to the populace. He used a 510V battery to obtain enough voltage to produce the flash. The studio units utilizing low voltage battery packs were often very large and heavy and not practical. Eventually with the advent of the transistor to produce enought voltage the units were smaller and more practical. In some cases too small. He invented a high speed electronic flash in a company called Strobo Research in Rochester, NY. Which was bought by Graflex and permitted him to retire at an early age. rather than use a very large electronic flash to produce high speed result, Ed Farber (I edited his column about flash) used what I think was a rectifier to take the low voltage from the batteries and make it a high voltage. These rectifiers were very large. With the advent of the transister in 1959, Multiblitz in Germany did away with the rectifier and used transisters to increase the voltage from the battery pack to produce a practical hand-held electronic flash unit.

Ed Meyers

Harold Edgerton was one of the inventors of strobe flash. Early strobe units were for motion study and used low intensity Neon lamps. The famous General Radio Strobotac is an example. AFAIK the first studio strobes were made by Kodak under the name Kodatron. These came out sometime around the late 1930s. They were very large and heavy lamps which ran on AC. The early ones were designed to produce the fastest flash time. They were very noisy due to the mechanical stress on the capacitors and other parts by the sudden change in energy state. I remember them sounding like pistol shots. Later Kodatrons had a resistor in series with the lamp to increase the flash time. They still stopped most motion but were quieter and had less problem with reciprocity failure effects, a major problem when the exposure times were on the order of 1/10,000 sec or less. I remember the name Strobo Research but not the trade-name they used. The use of high voltage batteries was made necessary by the lack of the kind of circuitry needed to generated it from a low voltage source without being large and heavy. Some early strobe flashes had built in delays to account for the M delay in many cameras. One could switch from X (instantaneous) to M as required. I believe most of the flash lamps were made by General Electric. Edgerton, Germeshousen, and Grier was the name of the company who controlled the strobe patents.

--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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