reverse polarity , could 'fry' a digital .
in [UK Photography]
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From: Gabriel Murray on 17 Feb 2010 11:04 And now for a situation that could ' fry' a digital - anybody know anything about a Courtenay Colorflash 100 Studio flash ? Is it reverse polarity ? What is its voltage ? It is a fabulous piece of British engineering in the Midlands from circa 1976 , part of the stock that survived their Halesowen factory fire in 2001 , gleaming new , mint, with stand and broll but I have no instructions for it . I guess it was never used , it ended up in a private home in Sutton Coldfield, England . I would hazard a guess that it's 100 W , low-powered unit, it's absolutely gleaming mint since 1976, you couldn't say that about many products, it's stainless steel rear rear panel for instance is minty mint, Courtenay must have been using a special alloy . Outside of frying a digital because of reverse polarity, these older studio flash units could blast a Canon DSLR , for example, with its high voltage - Nikons do better here, they can take up to 250 volts from a flash . Some Canons can only take as little as 6 volts from a flash unit, so be careful :-) But this Courtenay is a tribute to British engineering, wonder where that all went wrong ? I believe that Patterson owned Courtenay in the end, a fab firm . .
From: Gabriel Murray on 17 Feb 2010 11:25 On 17 Feb, 16:04, Gabriel Murray <gabriellomorri...(a)gmail.com> wrote: > And now for a situation that could ' fry' a digital - anybody know > anything about a Courtenay Colorflash 100 Studio flash ? Is it reverse > polarity ? What is its voltage ? > > It is a fabulous piece of British engineering in the Midlands from > circa 1976 , part of the stock that survived their Halesowen factory > fire in 2001 , gleaming new , mint, with stand and broll but I have no > instructions for it . I guess it was never used , it ended up in a > private home in Sutton Coldfield, England . > > I would hazard a guess that it's 100 W , low-powered unit, it's > absolutely gleaming mint since 1976, you couldn't say that about many > products, it's stainless steel rear rear panel for instance is minty > mint, Courtenay must have been using a special alloy . > > Outside of frying a digital because of reverse polarity, these older > studio flash units could blast a Canon DSLR , for example, with its > high voltage - Nikons do better here, they can take up to 250 volts > from a flash . Some Canons can only take as little as 6 volts from a > flash unit, so be careful :-) > > But this Courtenay is a tribute to British engineering, wonder where > that all went wrong ? > > I believe that Patterson owned Courtenay in the end, a fab firm . . The Courtenay is 17.12 volts , working to perfection, but there is this polarity question hanging over it. At a 100 Watts, what would be the guide number - I don't even have that, but I'm guessing that it's about 100 ( ft) at ISO 100 , and about half that with the broll, so 50 effective at ISO 100 . Between f4 and f5.6 on a studio Hasselblad, that's my estimation . Note the spelling " Colorflash " - they were going for the U.S. export market, don't know how they did though I see Americans discussing them on the net . I hear that they were a top studio flash in their day .
From: spacecadet on 17 Feb 2010 12:56 Bart Bailey wrote: > In Message-ID:<f23d9373-a5ab-4d51-bcaa-3f105fba2922(a)15g2000yqi.googlegroups.com> > posted on Wed, 17 Feb 2010 08:04:35 -0800 (PST), Gabriel Murray wrote: Begin > >> Outside of frying a digital because of reverse polarity, these older >> studio flash units could blast a Canon DSLR , for example, with its >> high voltage - Nikons do better here, they can take up to 250 volts >>from a flash . Some Canons can only take as little as 6 volts from a >> flash unit, so be careful :-) > > http://www.carlmcmillan.com/Optoisolated_Adapter.htm The guide number may be rather less than 100, but no matter, I get about f8 from a 200Ws Minilite with Portra 160 for a family group. That's with a second fill flash with a brolly. You'll be pushed to get f4 with 100ISO.
From: Woody on 17 Feb 2010 18:21 "Bart Bailey" <me2(a)privacy.net> wrote in message news:4b7c2337.1632171(a)bart.spawar.mil... > In > Message-ID:<f23d9373-a5ab-4d51-bcaa-3f105fba2922(a)15g2000yqi.googlegroups.com> > posted on Wed, 17 Feb 2010 08:04:35 -0800 (PST), Gabriel Murray > wrote: Begin > >> >>Outside of frying a digital because of reverse polarity, these >>older >>studio flash units could blast a Canon DSLR , for example, with >>its >>high voltage - Nikons do better here, they can take up to 250 >>volts >>from a flash . Some Canons can only take as little as 6 volts >>from a >>flash unit, so be careful :-) > > http://www.carlmcmillan.com/Optoisolated_Adapter.htm > Good circuit, save I would add a resistor, say 10K, between G and K to ensure that leakage current through the opto device did not trigger the external SCR. A 1nF cap across that resistor will remove any tendency to react to nearby radio transmitters of any sort. -- Woody harrogate three at ntlworld dot com
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