Old equipment

Discussion in 'Lighting Equipment' started by alan_ellman|1, Mar 17, 2012.

  1. I have a Kodak DSLR which like most current cameras has a dedicated OEM hot shoe flash unit. I would like to use my old Vivitar 283 flash. The camera does fire the flash. What are the disadvantages of using this flash vs. the new Kodak model? Thanks!
     
  2. Hi Alan,
    Whatever the age of your Kodak I am sure that it is not supplying the voltage required for that flash. I would not recommend using a DSLR of any age with an older flash unless of course you have some sort of circuitry protection device.
     
  3. I believe the very old version of Vivitar 283 produces very high sync voltage, that could be dangerous to your camera. Best if you could measure that voltage with an ordinary DC voltmeter, and consult your camera specification for allowed sync voltages.
     
  4. All Kodak Dslr's were Kodak modified Nikon/Canon film cameras.
    If you give us the Kodak model number we might be able to translate it to the corresponding model.
     
  5. +1 what the other guys said. Those ancient Vivitar flashes had sync potentials up to 600V. I am not making this up.
    I believe they changed the design sometime to use a much lower voltage. If you can date your flash unit accurately, you might be able to find reliable information on the interweb, with the risk that unreliable information may smoke your camera. (Because the trigger voltage is transient, the experts say you can't measure it accurately with your regular $20 Radio Shack multimeter, so don't rely on that.)
    Either use a slave, and physically disconnect the flash from the camera (no cord), or buy one of these gadgets. Or just get a new flash. You can always use the Vivitar on a cheap optical slave, as a fill light or something.
     
  6. I gather you can get an optical trigger for around $20 from B&H and use the dedicated flash to trigger it. I wouldn't use any 'old' flash with a digital camera unless I knew for certain what its trigger voltage was and what the camera can handle.
     
  7. "Those ancient Vivitar flashes had sync potentials up to 600V"​
    That's an exaggeration. The maximum steady voltage found inside any hotshoe mounted flash is around 360 Volts, and the synch voltage usually maxes out at somewhere well under that. However that's probably still high enough to damage a DSLR's hotshoe circuitry, although it should be safe if plugged into the P-C socket of a Nikon/Canon/Kodak pro quality DSLR.
    Alan, firstly check the voltage between the hotshoe centre pin and its side contact using a high impedance (=>10 Megohm) digital multimeter, or get someone with some electrical knowledge to check it for you. If the voltage is more than about 12V, then don't use the flash in the hotshoe, but rather trigger it from the coaxial P-C socket of the camera via a synch cable.
    Apart from that, there's really no disadvantage to using these old non-dedicated flashes with a modern DSLR. You just have to use a bit of brainpower when setting the right exposure, instead of relying on dumb automated TTL metering.
    I'm not sure why old Vivitar units are still so popular with "strobists" though. They're not very powerful, and the manual power setting isn't at all precise. You're better off with units like Canon's 540EZ or Nikon's SB-25. These are reasonably cheap these days, and both have better manual control, are more powerful and recycle quicker than those old Vivitar popguns.
     
  8. I would take some of those linked readings with a pinch of salt. From the variability of reports of the same model of flash, it's obvious that some of those voltage readings have been taken using a low impedance or just plain inaccurate voltmeter. Most of them are actually on the low side because they take no account of the series resistance of the trigger circuit.
    It appears that this site is also the source of the Vivitar 600V trigger rumour, which I'd strongly suggest is just that - a rumour. I have extensive experience of repairing and modifying flash units to lower their trigger voltage, and of all the consumer battery-portable flashes I've come across, only one has had a capacitor voltage in excess of 360 volts. That was an ancient Braun Hobby, which has a separate powerpack and head design. The capacitor voltage in the powerpack reached 500 volts at full power. Nothing else I've seen has come even close to that voltage outside of a studio strobe. Besides, capacitors with a working voltage of over 400 V are large and expensive, so I very much doubt that a small and cheap unit like the Vivitar 283 would ever have used one.
    I should explain that older and simpler trigger circuits tap the main capacitor voltage through a high resistance in order to charge a small value trigger capacitor. Without going into too much detail, this means that the trigger voltage seen by the camera can never exceed the voltage across the main storage capacitor. Therefore if the storage capacitor voltage is limited to around 360 volts, then the maximum trigger voltage will be limited to that as well. More modern circuits interpose a thyristor or high-voltage transistor between the internal trigger circuit and the hotshoe contacts, such that the synch voltage falls below the ISO recommended standard of 12 volts maximum.
     
  9. "(Because the trigger voltage is transient, the experts say you can't measure it accurately with your regular $20 Radio Shack multimeter, so don't rely on that.)"
    Trigger voltage is a static level voltage and there is nothing trsansient about it. Camera shutter brings this voltage to zero value, making the short circuit that dumps to zero the sync voltage and any possible transient signal. Doing this by either by mechanical switches or by semiconductor switches. Any possibly higher voltage spike or higher frequency peak caused by clamping down the sync voltage should be fractional and minimal comparing to the voltage level of the sync circuit.
    As long as a DC Voltmeter has an internal resistance of at least some 10 KOhms / volt, your can masure the sync circuit voltage perfectly safe.
    You can certainly rely on sync voltage level measurement, with a $20 multimeter from Radio Shack.
     
  10. Frank, those old high-voltage trigger circuits usually have a series resistance of several megohms; sometimes as high as 20 megohms. Therefore measuring the voltage with a 10Kohm voltmeter will give a gross under indication of the true open-circuit voltage. By about minus 99.5% worst case! Even a high impedance digital meter will cause quite a bit of under measurement on such circuits.
    This can have drastic consequences for any semiconductor device (i.e. digital camera) plugged into such a high voltage/low current source. The high potential can puncture the barrier layer of CMOS or destroy the junctions of bipolar devices through voltage breakdown. It doesn't matter that the current is limited to a few microamps, the damage is done by the high potential. In the same way that static can damage electronics.
    So if you have a camera P-C socket that's rated for 250 volts and you stick 320 volts across it, there's a good chance of permanent damage. All this means it's essential to measure the trigger voltage properly at as close to its open-circuit potential as possible, and not with some crappy low impedance moving coil meter that takes 100 microamps to give an indication!
    Luckily, the price of digital multimeters has fallen drastically and it's possible to get a reasonable high-impedance meter for a few pounds or dollars. Certainly for less than the repair cost of a DSLR. Even so, I'd recommend putting a 100 megohm resistor in series with the meter and then applying an appropriate multiplication factor to the reading.
     
  11. So if you have a camera P-C socket that's rated for 250 volts and you stick 320 volts across it, there's a good chance of permanent damage.​
    Whilst I wouldn't suggest doing it, a rating of 250 volts (as most current DSLRs are now specified) probably means a component rated at 400 volts is being used.
    If the component is an opto thyristor (as I suspect is used in most cameras now) it is not possible to get one rated at 250 volts, 400 volts being the minimum.
    Also, I disagree with comments suggesting it is unsafe on the hot shoe but safe on the PC socket. Both will have the same circuit and are very likely to be wired in parallel. The only danger with using the hot shoe is in sliding on a fully charged flash and having the sync. contact temporarily touch one of the other control contacts and causing some damage there. I think this is the source of much paranoia and mis-information.
     
  12. "Frank, those old high-voltage trigger circuits usually have a series resistance of several megohms; sometimes as high as 20 megohms." - no such thing...
    From high capacity flash capacitor there is a ladder of multi megaOhms resistors feeding fractional voltage and limitting current to very small flash trigger circuit capacitor. Measuring sync voltage is measuring voltage level on the trigger capacitor, and there multi megaOhms resistors are not in series with the sync circuit. Not in any commercially made flash.
    Measuring sync voltage with a 10 KOhms/Volt DC voltmeter measures exact syc voltage on the trigger capacitor, and voltage dropout on any in series resistor does not exist.
     
  13. Measuring sync voltage with a 10 KOhms/Volt DC voltmeter measures exact syc voltage on the trigger capacitor, and voltage dropout on any in series resistor does not exist.​
    Not quite. A typical sync. circuit would comprise of a 10nF capacitor connected to the high voltage supply via a 1M ohm resistor (or thereabouts). If this is measured with a fairly ordinary voltmeter, then the resistance of the meter forms a potential divider with the sync. circuit's source resistor.
    If the meter's internal resistance is also 1M ohm then the indicated voltage is actually half that of the voltage which would be present if the meter were not connected.
     
  14. If the meter's internal resistance is also 1M ohm then the indicated voltage is actually half that of the voltage which would be present if the meter were not connected.​
    It's a little more complicated as the meter is in series with the primary coil of the trigger transformer which is connected across the trigger capacitor via the sync contacts on the flash. The charge on the trigger capacitor is going to mostly negate the effect of the voltage divider circuit formed by the meter. Although a low resistance voltmeter would show a decreasing voltage as the trigger capacitor discharges thru the meter and the trigger transformer.
     
  15. No because the internal resistance of the meter is going to quickly partially discharge the capacitor down to whatever level the potential divider it becomes part of sets it to. It will probably discharge quicker than the time it takes for the meter's display to stabilise.
    As far as working out the voltage, the capacitor might as well not be there. Having the bottom end of the capacitor connected to ground via the trigger transformer primary makes negligible difference.
    Not all flashes are configured like that. Some are like this: http://repairfaq.cis.upenn.edu/Misc/kflashm.gif
    Just add a resistor equivalent to the internal resistance of the meter to this diagram and you will be able to work out what the voltage will measure at the sync terminals (if you know the main HV supply voltage).
    Obviously, any flash with this type of circuit will have a sync. voltage equal to the HV supply when there is no meter connected to the sync. terminals.
     
  16. Guys, you're giving an advanced class in electronics theory to a guy who only asked where to find the light switch. Alan--All you need is a Wein Safe Sync, about $50. This slides into the hot shoe on your camera and the Vivitar can either slide into it or connect by PC cord. It has circuitry that drops the Vivitar voltage -- whatever it might be -- down to about 6 volts so it is safe for modern digital cameras. As for Strobist types (like me) loving Vivitar flash units it's because they are the most reliable flashes and most flash for the money that were ever made. I have worked in the news business for more than 30 years and until TTL became popular, almost every single news photographer at every paper or wire service where I ever worked used Vivitar 283s and later 285s. Newspaper photographers need simple dependable equipment that absolutely works on every single shot, with no excuses about missing the picture. If they were using Vivitars, you can bet the mortgage that they were hockey pucks that could take a beating and be depended on. As for power, I believe the ISO 100 guide number is around 120, just under a Nikon SB-900. I have a 283 and three 285s (in additon to an SB-900) and use them all the time with my Nikon D200.
     
  17. I don't think Kodak ever made flashes for their DSLRs. The normal choice would be either a Canon or a Nikon flash unit depending on what model you have.
     
  18. My old 283 (from the seventies) measures 260 volts and the newer 285HV measures 3.89 volts with my meter. I wouldn't take a chance with the 283. You can buy a new 285Hv for less than $90. My 283 is so old who knows when it will breakdown. It is built like a brick though compared to the newer Vivitars.
     
  19. Alan, The limit I use for flash trigger voltage is 12V. I fried a Yashica FX-3 film camera with a 283 and am leery of doing the same to a DSLR. The Wein transformer is an excellent safeguard but aftermarket flashes for your DSLR will have TTL exposure that the old flashes don't.
    Randyc
     
  20. Craig is right. Get the Wein adaptor and be done with it. For buy a Nikon SB-24, which fires with just about everything. Both are about the same price, but I suspect the SB-24 is slightly dimmer than the Vivitar that you already own.
    As far as PC cables vs. hot shoes ... I don't know enough to comment on voltages. I DO know that for dedicated units (which the Vivitar is not), using them on the wrong brand camera may prevent the flash from firing properly, and the sync cable fixes this. I also know several people that use 283s with digital cameras (A good friend uses one with a D90) without them exploding. I can't tell you what the meter readings mean though.
     
  21. I also know several people that use 283s with digital cameras (A good friend uses one with a D90) without them exploding. I can't tell you what the meter readings mean though.​
    283s and 285s that I have come across are either around 80 volts or 5.6 volts. The HV designation which some people think indicates the 285 as low voltage is irrelevant.
    And the D90 is specified up to 250 volts so no problem there.
    you're giving an advanced class in electronics theory to a guy who only asked where to find the light switch.​
    Good point. It's over there by the door.
     
  22. Position of lightswitch notwithstanding. Some misinformation has now crept into this thread that might mislead others in future.
    @ Frank. The trigger capacitor is usually only around 10 nanoFarads in value. Work out how long the voltage is going to last on that before a 10Kohm meter resistance discharges it. If you can take a meter reading in that few milliseconds, then good luck to you!
    You can believe what you like Frank, but the truth is that the only way to get a halfway accurate reading of those high trigger voltages is with a high impedance meter. Try it for yourself for goodness sake! Measure something like an old hammerhead Metz that has a trigger voltage in excess of 250 volts, using both a digital high impedance meter and a 10K moving-coil meter. Then come back to us and tell us what respective readings you got. Any money says they'll be nowhere near the same.
     
  23. Measure something like an old hammerhead Metz that has a trigger voltage in excess of 250 volts, using both a digital high impedance meter and a 10K moving-coil meter.​
    I once tried to measure the voltage on a flash (probably one of my higher voltage Vivitars) with my Avo 8 moving coil meter. It's internal resistance is so low that it fired the flash!
     
  24. Wow... thanks for all the great responses! Very helpful. I think I fried an older Kodak model by using this flash on it.
     
  25. Craig S, and John C have given good advice.
    Last I heard, Nikons were rated for 250v,Canon for about 6v. (subject for review by experts).
    But,why risk it? If you have an on-board flash,consider a slave unit...cheaper than the Wein $50 alternative.
     
  26. But,why risk it?​


    There's no need to risk it. just read the manual for your camera and measure your flash and try not to be swayed by the paranoia.
     
  27. I have successfully modified two old flashes I had lying around, to have low voltage triggers. I made a simple printed circuit board and ordered some components from DigiKey. The total cost for the assembled board is something like $5 (Express PCB charges $75 for 3 PCBs, but each PCB contains 12 low voltage adapter boards) . Of course, I put some time into designing it and building the boards, but I'm not counting that :) My point is that it's not impossible to do, and if you can get a bunch of friends together or do it as a club project, for many flashes, it can be cheaper than buying Safe Syncs for all of them.
    I wrote up the conversion process for one of my flashes, here:
    http://ka1axy.blogspot.com/2013/01/converting-old-photo-strobe-to-low.html
     

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