Changing polarity should just be a matter of making a short adapter cord with the wires 'crossed over'. Older cameras used physical contacts to close the circuit so were not polarity dependent. With newer cameras it depends on what device they use, an SCR will be sensitive to polarity, a double SCR (Triac/Thyristor) won't.-
Don > -----Original Message----- > From: Jens Bladt [mailto:[EMAIL PROTECTED] > Sent: Saturday, December 18, 2004 12:06 PM > To: [EMAIL PROTECTED] > Subject: RE: Isolators_Was- "safe" Flash Sync Voltages > > > I think this is a great invention. > Would something like this be available with a device, that can > shift + and - > ? I know these (without the isolator) are necessary for some digital > cameras. I guess this is why my *ist D won't work with the studio strobe > outfit. > > Jens Bladt > mailto:[EMAIL PROTECTED] > http://hjem.get2net.dk/bladt > > > -----Oprindelig meddelelse----- > Fra: Don Sanderson [mailto:[EMAIL PROTECTED] > Sendt: 18. december 2004 16:49 > Til: [EMAIL PROTECTED] > Emne: Isolators_Was- "safe" Flash Sync Voltages > > > Here are the isolators I'm refering to: > > http://www.adorama.com/WNSSPC.html > http://www.adorama.com/WNSSHSHS.html > > Don > > > > -----Original Message----- > > From: Don Sanderson [mailto:[EMAIL PROTECTED] > > Sent: Saturday, December 18, 2004 9:32 AM > > To: PDML > > Subject: "safe" Flash Sync Voltages > > > > > > All the talk about 'safe' flashes to use on the D got > > me a little concerned. > > The last thing I want to do is damage the poor thing. :-( > > I took some measurements from various units that I use. > > > > Here are the sync pin voltages I measured from > > various flash units: > > > > Pentax 200T 4.65 > > Pentax 280T 7.18 > > Pentax AF-360FGZ 3.01 > > Pentax AF-500FTZ 3.55 > > Vivitar 285HV 5.80 > > Vivitar 285 6.24 > > Yake M-110 Studio Flash 8.09 > > > > I no longer have an O'Scope so I can't measure any > > 'spike' voltages present at the sync pin when fired. > > These spikes are what could do real damage. > > In a properly designed trigger circuit there should > > be no spikes but I can't prove their presence or > > absence on these units. > > > > As far as I can see the ist D manual only mentions these > > flash models: > > > > 240,330,360,400,500. > > > > The 360 and 500 I measured are the lowest sync pin voltage > > of the lot. This leads me to believe that the newer Pentax's > > are designed to operate at lower, (sub-TTL logic) levels. > > I'm reasonably OK with the 200T but the Yake and the 280T > > really scare me. > > > > There is such a thing as a "flash isolator" available. > > It fits in the hot shoe and protects the camera from > > overvoltage/spikes at the sync pin. > > > > I will be buying one very soon for the 285s and Yake! > > I will also not be using the 280T on the D anymore. > > > > > > Don > > > > >
