Is this a warning from Mamiya or just passed on hearsay? The Mamiya probably has mechanical contacts (just my assumption, not fact).
Originally Posted by MattKing
I just find it strange that a manufacturer of a camera (film or digital) would design a product which cannot use existing flashes and which could be damaged by them.
There are a lot of threads on Photonet about this. Many of them are from people worried about high sync. voltages on their DSLRS who don't realise that their cameras are o.k. Most are specified up to 250v but they have heard somewhere that old flashes can damage new DSLRs so are worried about it.
Putting aside my carefree attitude for a minute and putting my cautious head on, I would double those figures.
Originally Posted by tim_walls
The reason being that the voltage measured is via a high value resistor (as I described earlier). The meter's internal resistance will act with this resistor to produce a voltage divider.
Simplistically, if the flash's resistor is 1M and the meter's internal resistance is also 1M then a 12v sync voltage will only read 6v.
The amount by which the meter will affect the reading is probably related to the quality and cost of the meter. My ITT meter which cost a fortune ten years ago reads just under 11v when measuring a 12v power supply via a 1M resistor. This implies an internal resistance of around 11M which is quite good. The cheaper meters likely to be owned by hobbyists, etc. are likely to be a lot worse than this. Unfortunately I can't find a crappy meter here at work to prove my theory!
Using a meter will determine if your voltage is a matter of tens or hundreds though.
My father also has a Mamiya 645 so I thought I would look into it.
Originally Posted by MattKing
You probably already have it but the Mamiya 645 Pro manual is here: http://www.mamiya.com/assets/pdfs/645/645_Pro_TL_v8.pdf
On page 34 it gives this warning:
When using the Hot-shoe,
be sure to put an appropriate
Safety Cover over the X-sync
terminal so that you won’t
receive a high voltage
electric shock if the terminal
is accidentally touched. (A
Safety Cover is put on the Xsync
terminal when the
camera leaves the factory
This implies that high voltages are fine but warn you not to get your fingers near them!
This manual also shows examples of the camera set up with various Metz flashes.
The warning came from a local repair facility who at the time was authorized to perform Mamiya warranty work.
The Bowens monolights and Metz 202s that I have are both 30+ years old, so they may be an extreme example.
If I understand it correctly, the issue is whether the synch switching is either completely mechanical, or almost completely electronic, or takes some middle ground, and that the ability to handle high voltages turns on how much the switching is mechanical, and how heavy duty those mechanical switches are.
Vivitar 285HV tried for the first time
I finally had a chance to give my Vivitar 285HV a try. I was very satisfied. Here's one of the results (sorry about the quality of the scan. Dealing with photos on scanners and computers really isn't my cup of tea).
I ended up using the Vivitar 285HV with the Bessa R3A despite the flash's big size. It really looks excessive on the relatively small Bessa, but the flash seems to be a joy to use. I got good results without much previous experience after all. I bounced the flash off a white board held by the kid's mother. Following the instructions on the manual was all I did to set the flash.
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All of the Differences Between Vivitar 283's & 285's
WOW ! It's hard to know where to begin. There's so much mistaken information, here. So let's try this;
1. There are 2 different 283's as there are 2 different 285's.
2. All of these models can use 6 volt low voltage Quantum 1's, or 1+. Any modules, that fit into the battery compartment are for the low voltage Quantum battery.
3. The L.V. 285's, CANNOT use a Turbo. They weren't designed to use the H.V. pack, so they can't use a Turbo.
4. Aside A., when they came out with 285 H.V., they redesigned the 283's to lower the flash synch voltage. Only older 283's have a high synch voltage. All 285's have a low flash synch voltage.
5. I don't believe that you need to install AA batteries, to use a Turbo. I still own 2, 1 of which still works fine. I remember, Vivitar telling me, that only the flashes, that used an LCD, display, require AA's.
6. Stay away from the Vivitar H.V. 1 pack. The 510 volt battery is hard to find. The turbo's were invented as a substitute for the Vivitar H.V. 1 pack. The Turbo puts out about 300 volts. www.qtm.com
7. Aside B., All 283's & 285 H.V.'s use the same AC adapter. Because when they redid both flashes, they made them both similar inside. All 283's & 285 H.V.'s se the same Turbo power cord. Only the 285 L.V., uses a different AC adapter, which Vivitar promptly discontinued, when they discontinued the 285 L.V..
But here's a secret, the 285 L.V., AC adapter was also used for the Vivitar Polaroid Instant Printer.
So the joke was on them.
8. I was always worried I would fry the camera circuitry, because of the single ball connector in the hot foot. If both, the camera & flash are switched on, dragging the ball across multiple contacts on the hot shoe, could short the camera. So to avoid that, I changed the foot to the one made by Lindahl. It uses a HouseHold synch cord, instead of the little pin & the metal foot, required me to use a flash bracket, the best thing I could have ever done.
9. You can tell the difference, between 285 L.V.'s & 285 H.V.'s by the front label. The L.V.'s used Black lettering, on a Silver background, the H.V.'s used Silver lettering on a Black background. While it does say H.V. on the front, it can be easy to miss & if your eBay, hunting, this may be a more reliable way to spot, what you want.
10.. You must power up all Vivitar flashes every once in a while or the capacitor goes dead. It's hard to fix now, due to a lack of parts from Vivitar.
11. I'm told that the Chinese one's are junk, ( no pun intended ). Here's a web site that explains all about the new models. But even he has some of the facts wrong, about the older models. I owned, both L.V. & H.V. 285's. I still have the H.V.'s as back up. www.AlJacobs.com
I think this is the main reason for some camera manufacturers putting out warnings about using high sync. voltage flashes.
Originally Posted by Vanishing Point Ent.
If an internal circuit uses (probably) an opto-triac to fire the flash then it is very unlikely that one only rated to 6 volts is used. In fact, I expect it would be impossible to find one rated that low.
I now personally think that the warning is to prevent the scenario you presented. i.e. switched on, fully charged flash inserted into hot shoe and centre pin connects momentarily to one of the other pins causing damage.
Due to the design with these pins being offset to the sides, I can't really see it happening but I think this is the reason for most of the advised caution.
Yes apparently the Vivitar 285 H.V. does require 3 batteries.
apparently B&H sells a dummy battery for the Vivitar 285 H.V.. So, it MUST require one. I'll have to try mine, as I just got my Turbo fixed, it's been a while. Heres the link:
So, now I stand corrected. But I'd rather sit.