Wireless trigger and PC sync

Hallsy

Hallsy

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Andy
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I've done a little reading on this, but would rather be put right by those in the know!!

I've bought a Sunpak 30DX to use for off camera flash, I haven't got it yet so haven't measured the trigger voltage, but either way I gather that something like Cactus V2s or V4 transmitter/receiver kit would do the job for wireless stuff?

But, if I wanted to use the flash on camera (I think it's a Pentax module on the flash, I use a Canon 20D), to get it to trigger and also be safe for the 20D, would I have to use a hotshoe to PC sync adaptor?

Are there any wireless options where the transmitter also has a hotshoe mount and PC sync socket so I could use the flash on camera that way?

Oh, one other thing, I have read that the 422D has an auto off feature (30DX is same so I assume this has it too), but will be woken up by a radio transmitter, but not an optical one (not sure why). The CTR-301 receivers are optical right? Are the cactus's radio or optical?
 
Well, I've had a look around and can't say I've found anything yet that will do both jobs.

So, I reckon I'll go for the CTR-301P set from ebay to cover the wireless duties.

Then I'll just get a generic hotshoe with pc cable for using the flash on camera. Although, if the trigger voltage of my Sunpak is too high, does triggering it using a PC sync protect the camera, or is it no different to triggering it through the hotshoe?
 
I'm not so sure now.

Thinking about it, the sync voltage will still put across the ps sync connection when using a pc sync/hot shoe adaptor, and so will still risk damaging the camera.

I can't see why the manufacturers don't make the hotshoe/sync port safe to high trigger voltage, they'd only need to use an opto isolator.

Anyway, looks like if my 30DX voltage reads too high I'll have to use something like a Wein safe sync, but they're quite pricey. Might be worth just saving up for something like a 550EX or EF-500 super to use on camera if necessary.
 
You may well be OK.

If you look here: http://www.botzilla.com/photo/strobeVolts.html you can see the 30DX being given consistently less than 12v. Readings between 4.5 and 10 show a fair amount of variation but nothing frightening like 200v.
What is the limit on your camera?
I cant see that you are going to go through differnt circuits on the hotshoe and PC.
 
Hallsy said:
I can't see why the manufacturers don't make the hotshoe/sync port safe to high trigger voltage, they'd only need to use an opto isolator.
Click to expand...

In most cases they do. Check your manual. Most cameras are o.k. to about 250v.

Sometimes manufacturers put warnings on to stop you putting a high voltage flash onto the hotshoe. Not because the high voltage could damage the sync. connection but because of the possibility of accidently touching the sync. connection of the flash onto one of the other communication pins on the hotshoe.

I agree, it's really bad design to make a camera which is not compatible with existing flashes when an opto-isolator costing a few pence would have done the job.

Either that or it's a marketing thing to get you to buy a new flash!


Steve.
 
I meant I wouldnt expect different levels of protection to the trigger circuits.
 
Got the flash today, I'm getting a peak of 6.5V DC once full charged, which gradually goes back down to 5.5V DC. I'm measuring with my Fluke 177 meter, which should be pretty accurate, but I'm not sure of it's impedance, so may just get out the oscilloscope to check again.

Reading around it seems that the 20D is safe to sync up to 250V, so I reckon I'll be safe to use it on the hotshoe :)

It has a Pentax adaptor on it, is it worth disconnecting the other two pins, just leaving the centre pin - to be sure it couldn't cause any problems making contact with the TTL pins?
 
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