Off-brand flashes on Nikon cameras?

Discussion in 'Lighting' started by Erik Petersson, Jan 2, 2010.

  1. Erik Petersson

    Erik Petersson Subscriber

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    A couple of times I have stumbled upon a statement that Nikons, such as F3, can be destroyed by the use off off-brand flashes, as the voltage of some flashes would be too high for the camera.

    I wonder if anyone could comment on this, and explain what the case is.

    Thank you in ahead.
     
  2. PeteZ8

    PeteZ8 Member

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    Any camera that uses solid state switching for the flash (all DSLR's, most if not all AF bodies, and perhaps some manual bodies with auto exposure) can and will be destroyed by a flash with a high sync voltage.

    Back in the early days, the camera sync'd the flash with a mechanical contact attached to the shutter. The mechanical contact did not care if the signal voltage coming though the flash was 1 volt or 1,000 volts. As cameras advanced, the switching duties were assigned to a transistor for better accuracy, and more flexibility, such as rear curtain sync, FP sync, advanced TTL modes, etc. The problem is the transistors are not capable of handling more than 5 or 6 volts, or they can get nailed.

    Since for a hundred years cameras and shutters were all mechanical, the flash manufactures often paid little attention to how much power was being fed to the hot shoe or PC terminal. I have heard in some cases, although I cannot confirm, the voltage being up to 600vdc. More realistically, you are likely to encounter flashes with 10-50 volts from time to time. The older Vivitar 283/285's, for example, were fairly high I believe.

    If you're using a flash with unknown hot shoe voltage, it's often advised to use a "safe sync" adapter, or optical slave, or radio trigger. Unfortunately all of the above generally cost more than a more modern flash so it's pretty much a wash.
     
  3. Erik Petersson

    Erik Petersson Subscriber

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    This explains the problem. Thanks!
    /Erik
     
  4. Mick Fagan

    Mick Fagan Subscriber

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    I run F3 and FE2 Nikon bodies and use a Metz CT32 with the G15 handle and the correct Metz adaptor.

    With the same adaptors I have used both the Metz CT60 and CT45 in the past, various models of both flashes from a basic one through to full TTL models of flash and what have you.

    The F3 adaptor is called the SCA 341 for the standard Metz CT32 whilst I also have the SCA 344 for the CT45 units. I haven't used a Metz flash on the F3 for about 10 years now, so I'm a bit rusty with them.

    Mick.
     
  5. eddym

    eddym Member

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  6. Erik Petersson

    Erik Petersson Subscriber

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    Thanks Eddy. I think I will restrict the use of my Sunpak B3000 to my Zenit. The chart is excellent, but I managed to pick up a flash that does not show on it (the Sunpak B3000), so I don't want to take a chance. Well, maybe it could be used with my Nikon FM2, which is a manual camera... Hmm
     
    Last edited by a moderator: Jan 3, 2010
  7. epatsellis

    epatsellis Member

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  8. PeteZ8

    PeteZ8 Member

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  9. RalphLambrecht

    RalphLambrecht Subscriber

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    This must be a typo on their part. They must mean 25V. Hardly any flash has a trigger voltage as high as 250V, but 250V will definitely fry your digital SLR. According to ISO 10330, all cameras must accept trigger voltages of up to 24V. Unfortunately, not all cameras manufacturers stick to that, and flash manufacturers exceed it.
     
  10. eddym

    eddym Member

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    I think that somewhere on that same link he explains how to measure the firing voltage of your own flash. It's really easy if you have a voltmeter; just measure across the contacts of the flash as you trigger it. I've tested all of mine, just to be sure.
     
  11. Erik Petersson

    Erik Petersson Subscriber

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    You are right Eddy. However, I do not plan to spend money on a voltmeter for which I will not have other use. Better instead to save them for a TTL-flash for my F3, when I stumble upon one.
     
  12. RalphLambrecht

    RalphLambrecht Subscriber

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    Just wait until you get the bill for all these suggestions! :smile:
     
  13. Erik Petersson

    Erik Petersson Subscriber

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    I thought I paid that already. Or was that the heating bill? :wink:
     
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  15. Steve Smith

    Steve Smith Subscriber

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    I think 250 volts is correct as most flashes in the Nikon F3/4 era would have had sync. voltages a lot higher than 25 volts.

    Most DSLRs are o.k. up to 250 volts (my D100 was and I think all subsequent Nikons are rated at 250V too) and many flashes have sync. voltages in the 100 - 200 range.

    Before digital appeared, no one even thought about it. They bought a flash and connected it to their camera and used it with no problems.

    There is currently some thinking that some DSLRs are only safe up to 6 volts. I think this is largely a myth for two reasons.

    First, any competent camera designer would include an opto-triac or thyristor in the sync. circuit. These do not exist with such a low maximum voltage.

    Secondly, some people have stated that a high voltage flash is o.k. on a PC connector but not the hotshoe (of the same camera). I think this is nonesense too as they would both either be wired together or have similarly specified circuits.

    My thinking is that the manufacturers are dissuading people from using high sync. voltage flashes on hot shoes due to a fear of the centre pin touching one of the other communication pins when sliding a charged flash onto a hot shoe and damaging some other part of the circuit rather than the sync circuit itself being damaged.

    It could also be a bit of sales propaganda to get people to buy new 'safe' flashes when they buy a new camera.


    Steve.
     
    Last edited by a moderator: Jan 4, 2010
  16. Steve Smith

    Steve Smith Subscriber

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    Don't fire it - Just let it charge until the ready light is on and measure it. At the point of firing, the voltage will be (close to) zero as the sync. contacts short out.

    Most flashes have a circuit consisting of a high resistance (about 1M) charging a low value capacitor (about 10nF) from the main HV supply. The sync. contacts short this charge into the trigger transformer which produces a high voltage pulse which ionises the xenon in the flash tube causing it to conduct. Unless it is stopped by another circuit (auto/TTL/etc.) it will continue conducting until the main HV capacitor is empty. At this point it will stop drawing current and the HV supply will start to charge the main capacitor again closely followed by the little capacitor in the sync. circuit.


    Steve.
     
  17. RalphLambrecht

    RalphLambrecht Subscriber

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    Steve

    I really don't know but a couple of things don't seem to add up:

    1. This website lists a lot of trigger voltages and I can't find a single one at or above 250V. http://www.botzilla.com/photo/strobeVolts.html

    2. I'm looking at ISO 10330:1992. It limits electronic flash trigger voltages to 24 V and sets this value as the camera minimum.

    Any thoughts?
     
  18. eddym

    eddym Member

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    Come to think of it, you're right. What I'm remembering is that it's hard to touch the probes to the pc connectors for a reading without firing the flash. With a shoe mount it's easier. I was checking the pc's on my Sunpak 622 and my Calumet Travellites, and they were always firing accidentally.
     
  19. RalphLambrecht

    RalphLambrecht Subscriber

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    Steve

    Would it help to connect the voltage meter to the flash contacts with, let's say, crocodile clamps, and then, give the flash time to charge up before taking a reading?
     
  20. MattKing

    MattKing Subscriber

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    FWIW, I had some work done in 2006 on one of my Olympus flashes (3 foot drop on to tile floor = broken shoe) and the repair technician was saying then that they were doing a thriving business repairing digital and newer film cameras that had suffered damage when an older, higher voltage flash was connected.

    I had a Metz 202 flash until recently, and the 200+ volt trigger voltage is one I wouldn't even consider using with my Mamiya 645 Pro (my newest camera with a flash shoe or synch socket).

    Matt
     
  21. John Koehrer

    John Koehrer Subscriber

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    Older studio flash could hit that 250V threshold no problem.
     
  22. Steve Smith

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    If you connect a meter up then turn it on, you will see the sync. voltage rise as the main HV supply charges as it is usually derived from this supply.

    Another thing to keep in mind is the internal resistance of the meter you are using will have some effect.

    e.g. if the circuit is as I have already described with a 1M resistor supplying the current to charge the sync. capacitor then if you had a meter which had an internal resistance of 1M, it would show a reading of half the actual voltage.

    Modern meters have higher internal resistance and one with a value of 10M would show 90% of the actual voltage.

    My old AVO 7 moving coil meter however has quite a low resistance. I don't know what it is but it is enough to fire the flash! (Vivitar 285).


    Steve.
     
    Last edited by a moderator: Jan 5, 2010
  23. Steve Smith

    Steve Smith Subscriber

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    Lots of flashes were made before 1992 and in my opinion, a camera designer should take account of that and make sure his product is compatible.

    As far as ISO 10330 is concerned. The logical way to handle it is to set all flash voltages low but make the camera compatible with a much higher voltage - just in case.


    Steve.
     
  24. RalphLambrecht

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    Which one? There are none on this exhaustive list. My old Speedotron has a trigger Voltage of 68 Volts, and I would not hook it up to any of my cameras, analog or digital. Carl Zeiss told me that their Hasselblad lenses can live with that Voltage for some time but will wear over time. Nikon in Germany told me to stay below 5 Volts for their digital SLRs.
     
  25. Mike Wilde

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    I tend to play it safe, and order little hot shoe optical slaves with a PC socket on the side off the *bay from Hong Kong for use with some of my older potatoe masher type flash units with pc synch leads. They cost no more than $15 including shipping and taxes, and tend to last about a year before the high voltages I plug into them tend to cook them off and they stop working.

    I trigger these slaves with a small low synch voltage flash on the senstitive camera, with a piece of black e6 film taped across the flash window on the camera, since this film passes the IR that the slaves need to trigger, but not the on camera optical output that I am usually trying to suppress when shooting with multiple flashes for portraits etc.

    I run an old Metz 60CT2 that synchs at about 380 V per measurement with a 10Mohm digital VOM, and a Braun Hobby EF300 that synchs the same at half power, and closer to 580V at full power. Both these head and pack flash sets offer a guide number that is 180 in feet, so they are useful for firing into umbrellas and soft boxes and still have worthwhile amounts of light coming out of the modifier for shooting meduim format portraits at the likes of 160iso and f/8.

    If I need more light and there is AC on the location I haul out the Speedotron Blackline pack fitted with a Wein HSS, and its associated heads.

    But it is nice to be able to do on site work with 'just' a case for the camera, another for the pack flashes and trigger flash and flash meter, and a case for the light stands, modifiers and tripod. This can fit into the back of my wife's compact car. The Blackline set comes closer to filling the back of my pickup truck, but then I have enough light to fill a whole theatre if need be.
     
  26. John Koehrer

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    How's about the old Ascors from the '70's?