Sync voltages for Nikon DSLRs + PocketWizards; sync cord polarity:

[studio460]

<p><em><strong>Sync-Trigger Voltage/Polarity Questions:</strong></em></p>

<p>1. Are the following strobes safe for hard-wire connection to: Nikon D3s/Nikon F6, hot-shoes/PC connectors?<br /> 2. Can having the wrong polarity on a sync cord damage anything?</p>

<p>Since I recently purchased a number of strobe units from different manufacturers, I now need to buy all of the appropriate sync cables, and the subject of sync voltage came to mind. After a some avid Googling, I found the following data (listed below) for the particular strobes I bought. First, I'd like to confirm/correct Thom Hogan's Nikon sync voltage figures he mentioned in another forum (cited for a Nikon D700), which was the source for the the Nikon data listed below (16V/250V).</p>

<p>Secondly, I have a Dynalite Uni400JR with a three-pronged, household-type (Edison) female sync input. I found the Quantum PC to three-prong cable at B+H, designed for their radio slaves. The B+H item description is listed here: <a href="http://www.bhphotovideo.com/c/product/43371-REG/Quantum_Instruments_536_Radio_Slave_4_4i_Cord.html">http://www.bhphotovideo.com/c/product/43371-REG/Quantum_Instruments_536_Radio_Slave_4_4i_Cord.html</a>. Will this work?</p>

<p>Thirdly, I also bought an old Quantum Qflash model T with a polarized household-style Edison sync input. Again, another Quantum slave cable seems to fit the bill, but the Quantum cable appears unpolarized. The B+H item description is listed here: <a href="http://www.bhphotovideo.com/c/product/43367-REG/Quantum_Instruments_534_Radio_Slave_4_4i_18.html">http://www.bhphotovideo.com/c/product/43367-REG/Quantum_Instruments_534_Radio_Slave_4_4i_18.html</a>. Will this work?</p>

<p>[Note: I'm currently using a Nikon AS-15 hot-shoe PC adapter on top of one of my FlexTT5s. I just think it's a nicer connection to work with, and more robust than having a mini cable sticking out of the back of the transceiver. I plan to buy AS-15 adapters for each of my TT5s, and connect each strobe with a male PC connector on that end].</p>

<p><strong><em>Maximum Nikon Sync-Trigger Voltages:</em></strong><br /> Nikon 2009+ DSLR maximum hot-shoe sync voltage = 16V<br /> [source: <a href="http://forums.dpreview.com/forums/read.asp?forum=1021&message=31839928">http://forums.dpreview.com/forums/read.asp?forum=1021&message=31839928</a>]<br /> Nikon 2009+ DSLR maximum PC-connector sync voltage = 250V<br /> [source: <a href="http://forums.dpreview.com/forums/read.asp?forum=1021&message=31839928">http://forums.dpreview.com/forums/read.asp?forum=1021&message=31839928</a>]</p>

<p><strong><em>Maximum PocketWizard Sync-Trigger Voltages:</em></strong><br /> PocketWizard MiniTT1 for Nikon maximum sync voltage = 50V [source: PocketWizard FAQ for Canon.]<br /> PocketWizard FlexTT5 for Nikon maximum sync voltage = 50V [source: none.]</p>

<p><strong><em>Sync-Trigger Voltages for Selected Flash Units:</em></strong><br /> Quantum Qflash model T = 8V<br /> [source: <a href="http://forums.dpreview.com/forums/readflat.asp?forum=1019&message=5823240&changemode=1">http://forums.dpreview.com/forums/readflat.asp?forum=1019&message=5823240&changemode=1</a>] <br /> Dynalite Uni400JR = 9.6V<br /> [source: <a href="http://photocamel.com/forum/lighting-technique/48125-flash-syncing-voltage-sony-a700-300w-strobe.html">http://photocamel.com/forum/lighting-technique/48125-flash-syncing-voltage-sony-a700-300w-strobe.html</a><br /> Speedotron Force 10 = 6V [source: Speedotron user manual]</p>

<p>Here's an older list of sync-trigger voltages for additional strobes here: <a href="http://www.botzilla.com/photo/strobeVolts.html">http://www.botzilla.com/photo/strobeVolts.html</a> One of the most-varied entries listed there are my old Vivitar 283s. Based on which vintage I own, they could be anywhere from 10V to 600V!</p>

<p>Any corrections or advice would be most appreciated!</p>

[steve m smith]

<p>Most Nikon DSLR manuals state a maximum of 250 volts. Not sure where the 16 volt figure comes from.</p>

[studio460]

<p>Yes, I just found two other online references (from other forums) which claim the Nikon hot-shoe is also rated for 250V. Will check camera manuals when I get a chance.</p>

[jcuknz]

<p>If you short out the pins of the 'three pin connector' in turn [ A-B,B-C,A-C etc] with a metal 'something' the flash will go off and those two pins are needed to trigger the flash. <br>

I think an essential tool for a photographer is a volt meter, doesn't have to be an expensive one, but invaluable for checking circuits and trigger voltages by holding one probe to the earth and the other to the pin of the flash connector/hot shoe mounting.<br>

If you want to use a high voltage gun there is the Wein adaptor which isolates the camera from the flash guns voltage. I believe there are other makes too.<br>

A less satisfactory way of using these high voltage guns, I have two Vivitars and other units, would be to get yourself an optical trigger* [ $18<$38 B&H ] to fire them and mount this on the camera hot shoe and mask [ perhaps] the camera's own flash so that it triggers the slave unit ... but you would only have the automatics in the flash unit to help you instead of TTL. A possible problem with this set-up is that the focusing weak flash may trigger the slaved unit. I masked off the camera flash in case this happened and only let a small amount of the camera's flash escape to trigger the slave. Experiments, trial and error :-)</p>

<p>*They come in various forms and for this purpose you would need the type with a 'hot shoe' base and top and also a plug hole to fit the flash's sync cable. If no cable then one which has a pin to trigger the flash in its top 'hotshoe' mounting. From memory I have one of each :-) [ and others with suction cups to stick to flash units with plug holes for sync cable connectors ] Mine came from Jessops in the UK but I couldn't see any last time I looked at their website.<br>

Polarity ... normally these units have a co-axil cable with a central 'hot' wire and wrapped around insulation is a mesh of wire which is the earth. But I have not met with your equipment.</p>

[studio460]

<p>Well, I just searched the Nikon D3s user manual PDF with the terms "sync voltage" with no results.</p>

[studio460]

<p>JC:</p>

<p>Thank you for your detailed post. However, I'm not looking at alternative ways to trigger my flashes. I already own PocketWizard TT1/TT5 RF triggers and a pile of old Wein optical triggers. I have a number of flashes I'm trying to test, and don't have all the sync cables handy, so I'm using whatever's available. I also own a Nikon AS-15, which means I can hard-wire trigger from any Nikon body. But since the AS-15 sits on the camera's (or PocketWizard's) hot-shoe, I was just wondering if there's any risk of using it with older strobes of varying sync-trigger voltages. Also, if I can just verify the "safe" Nikon voltages, there won't be any need to buy any expensive "voltage-protected" sync cables or adapters.</p>

[steve m smith]

<p>Manual: <a href="http://support.nikonusa.com/app/answers/detail/a_id/16624/~/user's-manual---d3s---guide-to-digital-photography">http://support.nikonusa.com/app/answers/detail/a_id/16624/~/user's-manual---d3s---guide-to-digital-photography</a></p>

<p>On page 191. Do not use negative voltage or voltage over 250v. </p>

[studio460]

<p>Thanks, Steve! I don't know why I couldn't find that. The complete reference indicates that this applies specifically to the hot-shoe. Now, since it says that any negative voltage could damage its circuits, does that mean that incorrect sync cord polarity <em>could</em> damage the camera?</p>

[steve m smith]

<p>It depends on the component they used to trigger with. If it is a triac, it will trigger either way. If it is a Thyristor, it will trigger one way and not the other but do no damage. If it is a transistor it will trigger one way and possibly damage it the other way round.</p>

<p>The trigger circuits of most high voltage sync. flashes consist of a very large resistor charging a small capacitor. When the shutter contacts or triggering circuit is activated, it discharges the capacitor into a small transformer to produce a high voltage pulse which ionises the tube and starts it conducting. The charge in the capacitor is very small and is unlikely to cause damage to a transistor but there is always a possibility which is why there is some caution.</p>

<p>The full power of the flash high voltage supply does not pass through the sync. contacts to power the tube as some people erroneously think.</p>

<p>The only item I have taken apart to check the triggering component of is a cheap Cactus radio trigger. The receiver uses an opto triac rated at 400 volts (and I think the manufacturer conservatively rates the product at 250 volts). I would be very surprised if camera manufacturers didn't use the same component as there is no reason not to, but without taking some cameras apart, I can't tell.</p>

[henryp]

<blockquote>

<p>I also own a Nikon AS-15, which means I can hard-wire trigger from any Nikon body. But since the AS-15 sits on the camera's (or PocketWizard's) hot-shoe, I was just wondering if there's any risk of using it with older strobes of varying sync-trigger voltages.</p>

</blockquote>

<p>The AS-15 is a hot shoe to PC adapter but not a voltage filter. A Speedotron or Wein Safe-Sync Hot Shoe High Voltage Sync Regulator will combine the functions of the AS-15 and a voltage filter.</p>

<p>Henry Posner<br /><strong>B&H Photo-Video</strong></p>

[studio460]

<p>Henry said:</p>

<blockquote>

<p>The AS-15 is a hot shoe to PC adapter but not a voltage filter. A Speedotron or Wein Safe-Sync Hot Shoe High Voltage Sync Regulator will combine the functions of the AS-15 and a voltage filter.</p>

</blockquote>

<p>Thanks, Henry. But since the Nikon D3s manual states up to a +250V trigger sync may be used with its hot-shoe (and, I assume, its PC connnector as well), high-voltage isn't a concern. It's negative voltage which can damage the camera's circuits (as the manual states), which reverts back to my original question: can reversing the polarity of a sync cable (i.e., an unpolarized Edison household cable) damage the camera?</p>

[steve m smith]

<blockquote>

<p>which reverts back to my original question: can reversing the polarity of a sync cable (i.e., an unpolarized Edison household cable) damage the camera?</p>

 

</blockquote>

<p>Possibly. I think it would be a fool of a designer who would create a camera trigger circuit which could be damaged by reverse polarity (and high voltage) when a robust, either way round circuit could easily be provided for minimal (or no extra) cost.</p>

<p>However, the manual states no reverse polarity so it's best to keep it all the same.</p>

<p>If you have a multimeter you can check using the resistance range or a continuity buzzer if it has one. As long as the outer at one end connects to the outer at the other end (and by default, the centre pins at each end are are connected together) then you will be o.k.</p>

<p>I personally wouldn't use the same connectors for a flash as are used for mains powered things as there is the obvious potential to plug your flash or your camera into the household power.</p>

[studio460]

<p>Steve:</p>

<p>Thank you for taking the time to post those technically detailed answers. I read somewhere that analog VOMs won't work--you need a digital multimeter. I believe I have one somewhere, but I have no idea where it is.</p>

<p>Steve said:</p>

<blockquote>

<p>I personally wouldn't use the same connectors for a flash as are used for mains powered things as there is the obvious potential to plug your flash or your camera into the household power.</p>

</blockquote>

<p>Well, therein lies the crux of the problem. My Quantum Qflash has a polarized, household-style, Edison sync input. I'm trying to find a short, coiled PC-to-Edison sync cable, and the only one I can find at B+H's site is the Quantum slave cable. Unfortunately, from the online photo, the Quantum cable appears to be unpolarized. I know, I could test, and use the cable only in one orientation, but when doing things quickly, I sometimes make mistakes. I would just hate to ruin a $5,200 camera someday by simply accidentally reversing a sync cable's polarity.</p>

[studio460]

<p>Steve said:</p>

<blockquote>

<p>It depends on the component they used to trigger with. If it is a triac, it will trigger either way. If it is a Thyristor, it will trigger one way and not the other but do no damage. If it is a transistor it will trigger one way and possibly damage it the other way round . . .</p>

</blockquote>

<p>Again, thank you for sharing that technical description. I only have three flashes to vet:</p>

<p>1. Quantum Qflash model T: Because this is a thyristor-based, "auto-flash," would this then be one of the "safe" flashes? (i.e., it will either work or it won't). The model T is, I believe, about a 15-year-old design (or older).</p>

<p>2. Dynalite Uni400JR: What's your best guess on this one?</p>

<p>3. Speedotron Force 10: And, this one?</p>

<p>Both the Dynalite and Speedotron products have been on the market for I think ten years or more, but I don't know if any of their internal electronics have ever been redesigned or "upgraded" (I think the Dynalite may have been at one time).</p>

<p>Schematics aren't generally available for these products, and the user manuals for monolight-style flash units tend to be awfully light on technical specifications. I guess a call to the manufacturer wouldn't hurt, but you so often get that standard, disclaimer-speak: "We haven't tested our product with brand 'Y' so we can't make any claims of 'compatibility.'"</p>

[studio460]

<p>Upon searching photo.net, I found an interesting, yet somewhat disturbing thread about the Wein Safe Sync product here: <a href="00FIHN">http://www.photo.net/photography-lighting-equipment-techniques-forum/00FIHN</a></p>

[steve m smith]

<p>I can't guess on any of those. A flash having a thyristor is not an indication of it's sync voltage. All flashes which have variable output power (manual and/or automatic) will have a thyristor - more likely two). It was just used for a while as an advertising buzzword when they first came out to differentiate them from the earlier, uncontrollable types.</p>

<p>The only way to tell reliably is to turn it on, wait for the ready light to come on and measure the voltage across the contacts.</p>

[studio460]

<p>Steve said:</p>

<blockquote>

<p>I can't guess on any of those. A flash having a thyristor is not an indication of it's sync voltage. All flashes which have variable output power (manual and/or automatic) will have a thyristor - more likely two.</p>

</blockquote>

<p>Thanks for your reply. I wasn't referring to the max sync voltage issue. All of my strobes' sync voltages are at 10V or below, and we've confirmed that the Nikon D3s' hot-shoe can handle +250V. I was referring to your triac/thyristor/transistor comment, vis-a-vis, whether reversed polarity can damage the camera's circuits or not, based on that particular component's design.</p>

[steve m smith]

<p>I wouldn't like to give any guarantees but based on a maximum voltage of 10v I wouldn't expect any damage to occur with reverse polarity. I would expect a good designer to put a protection diode across the trigger transistor (but if he used a transistor in the first place, I wouldn't consider him to be a good designer!).</p>

<p>My guess, based on the advice in the manual, is that there is either a transistor or a thyristor used which is likely to have a protection diode. This diode will protect against reverse polarity to a point but at high voltages, is likely to break down and then present the reverse voltage to the triggering component.</p>

<p>My best advice would be to connect the flash up to the lead but not connect to the camera. Measure the voltage at the hotshoe adaptor and if the voltage on the central pin is positive, then you are o.k.</p>

[studio460]

<p>Thanks again for your advice!</p>

[peter_poremba]

<p>The sync voltage on a Uni400 is 10 volts and the center blade has no function. It only prevents the cord from being plugged into a AC outlet.</p>

[studio460]

<p>Peter said:</p>

<blockquote>

<p>The sync voltage on a Uni400 is 10 volts and the center blade has no function. It only prevents the cord from being plugged into a AC outlet.</p>

</blockquote>

<p>Thanks, Peter! I actually just found the scanned user manual online at Dynalite's site, and it does say 10V. On my way home from work today, I picked up a house-brand, polarized PC-to-household sync cable at a local dealer for only $7.99. I thought I was all set, but now I realize that the three-pronged Dynalite sync socket is <em>not</em> polarized. I just connected the PC cable to a Nikon N90s film SLR, and the Dynalite will trigger when the sync cable is plugged in <em>either way</em>. I'm trying to prevent sending negative DC voltage to my D3s, as per the D3s' user manual intructions. So, now I'm going to look for my digital multimeter to try to determine its polarity . . .</p>

[studio460]

<p>Well, all I could find was a cheap Radio Shack analog multimeter. When I inserted the hot lead into the socket where the wide blade of a polarized plug would go (based solely on the orientation of sync cord's angled-down, molded-plastic, plug housing), the meter jumped to the right. When reversed, the voltmeter needle rose to one-third of the scale, and upon test-fire, the neeld would jump to the left. I assume "jumping right" indicates "correct" polarity, if choosing that socket as the "hot" side, and vice-versa.</p>

<p>Does this sound correct?</p>

[studio460]

<p>Try and figure this one out:</p>

<p>Metered everything. Center PC connector lead is the hot side. Hot side of polarized plug is plugged into hot side of Dynalite sync input ("top" slot). Everything checks out.</p>

<p>Condition 1: Three-prong, Dynalight-supplied, household-to-PC cable --> Nikon AS-15 --> FlexTT5<br /> Result: Pass--both TT5 "test" button and RF signal from TT1 triggers Dynalite to fire.</p>

<p>Condition 2: Two-prong household-to-PC cable --> Nikon AS-15 --> FlexTT5<br /> Result: <em><strong>FAIL</strong></em>--neither the TT5 "test" button, nor the RF signal sent from the TT1, triggers the Dynalite to fire. In this condition, merely inserting/removing the two-prong plug into the Dynalite's sync port causes the flash to fire (i.e., the FlexTT5 is somehow causing it to short upon insertion).</p>

<p>Condition 3: Two-prong household-to-PC cable --> Nikon AS-15 --> Nikon N90s hot-shoe<br /> Result: Pass--shutter release on N90s triggers Dynalite to fire.</p>

<p>Condition 4: Two-prong household-to-PC cable --> Nikon N90s PC sync input<br /> Result: Pass--shutter release on N90s triggers Dynalite to fire.</p>

<p> </p>

[studio460]

<p>An even weirder sync cord issue occurred with the Qflash:</p>

<p>When testing the two-prong, $7.99 household-to-PC cable with the Quantum Qflash, and inserting the cable's polarized, household end into the side of the Qflash's polarized sync input as shown below, the following results were achieved:</p>

<p>Condition 1: Qflash --> household-to-PC --> Nikon AS-15 --> TT5 hot-shoe<br /> Result: <strong><em>FAIL</em></strong>-- Qflash fired continuously (Qflash is in manual mode), without any signal being sent.</p>

<p>Condition 2: Qflash --> QF-12 --> TT5 hot-shoe<br /> Result: <strong><em>FAIL</em></strong>--The QF-12 is an old-school Quantum TTL cable which plugs into the multi-pin "accessory" jack on the back of the Qflash. In this condition, the TT5 fires only intermittently, requiring constant reboots to fire at all. Apparently the non-i-TTL circuit in the Quantum QF-12 TTL cable is sending an incompatible (i.e., irrelevant) signal to the TT5, confusing it.</p>

<p>Condition 3: Qflash --> QF-12 w/TTL contacts taped --> TT5 hot-shoe<br /> Result: Pass--the TT5 fires the Qflash reliably when sent an RF signal from the on-camera TT1.</p>

<p>[Note: In the above sync cord tests, multiple household-to-PC sync cords, and multiple Nikon AS-15 PC-to-hot-shoe adapters were tried with identical results.]</p>

[ian_casement]

<p>Nothing technical but.. I stick a red dot on my slave cells, HH plugs and on my flash units so that I can align them quickly. Mostly the dots are the all the same way around, but some items are oppositely polarised to expected, but the dots sort them out.</p>

<p>When I tried a T5D-r and TTL adapter with a TT5 with a TT1 controller, all I got was a pop,pop,pop,pop from the Qflash. It didn't work.</p>

<p>I'd take the AS-15 out of the equation and remove the QF-12w too. If you're going to use these combinations, just go with the cable connection to the TT5 sync. A simple HH adapter cable with a red dot indicator is as simple as it gets.</p>