Can someone explain what a PC synch cable is?

[NathanO]

I've been interested in doing some photography with my flash located off the camera body. One thing I've seen around are some $60-70 coiled cords that would attach to the hot shoe on the camera, then to the flash. What I can't understand is the difference between that and using a PC synch chord. Can't I just use one of those PC cables directly? Does that just trigger a flash signal to where I need to adjust my flash manually? Do I loose E-TTL? I'm going to be using this in a slow paced environment so I actually have time for manual settings....

My equipment is a Canon 50D and I have the Canon 580EX-II.

My debate is to experiment with off camera flash using the PC-Sync OR with the Cactus V4 setup. Eventually I'd upgrade, by my concern now is just to learn how off camera flash affects what the picture looks like.

Thanks for your help!!

-Nathan

[zona5101]

There are some pc cords that are TTL, meaning they will communicate all the same data between the flash and camera just like if the flash was mounted on the camera. These will be manufacturer brand specific...in your case for Canon.

The plain pc sync cord only communcates the fire signal from the camera to the flash. Some cameras do not have a dedicated pc sync connector port and to use a pc cord these owners have to use a hot shot to pc adapter. Same goes with flashes, some do not have a port to plug into so ownwers of these have to use a pc to hot adapter.

If you are using a 'regular pc' cable and not a Canon ttl cable, then you will need to shoot in manual. If you use radio triggers like the Catus, you will shoot in manual as these only communicate the "fire" command. There are some radio triggers that retain the TTL functionality but they are pretty pricey.

[sybren]

Originally Posted by zona5101

There are some pc cords that are TTL

PC cords do dumb sync only, and TTL do actual data communication. How do you combine the two in one cable?

With PC (and Cactus) you only get get the sync signal, so indeed you'll have to go manual. If you want to retain ETTL-II functionality, there are a few other options:

• Canon's IR-based system. Works very well, but you either need an EOS 7D, a ST-E2 or a 580EX(-II) on the camera as a master.
• PocketWizard FlexTL system. Only do TTL, so no manual, and expensive but reliable
• TTL cord
• Radio Poppers, no experience with them but also need a master like Canon's IR-based system.

[inkista]

Originally Posted by NathanO

What I can't understand is the difference between that and using a PC synch chord. Can't I just use one of those PC cables directly? Does that just trigger a flash signal to where I need to adjust my flash manually? Do I loose E-TTL? I'm going to be using this in a slow paced environment so I actually have time for manual settings....

Those coiled cables are typically used for connecting the flash to the hotshoe when the flash is on a bracket. You'll note that the hotshoe connector has all five contacts for communication. This is how eTTL, high-speed sync, rear-curtain sync, setting the flash power from the camera back, and the Canon proprietary wireless communication is done. You need those extra pins/contacts so that the camera and flash can "talk" to each other. That's why some folks buy them (or their eBay imitations), slice them in half, and extend them with CAT-5 cable or the like: to get that extra functionality.

If you use a PC cable (or most cheap radio triggers), you basically only have a two-part connection: ground and the signal. The only communication that can be done between the camera and the flash is the camera telling the flash to fire. That's it. That's why you have to work with the flash in Manual mode if you want to control the flash power level.

My debate is to experiment with off camera flash using the PC-Sync OR with the Cactus V4 setup. Eventually I'd upgrade, by my concern now is just to learn how off camera flash affects what the picture looks like.

Most people will tell you to go for the eBay triggers, particularly if you're on a low budget. They don't cost much more than a PC cable, and you'll have the convenience of wireless, and as you say, chances are good you were going to upgrade, anyway.

If you're on a high budget and using off-camera flash indoors, you may want to consider just getting another Canon EX speedlight (or an ST-E2), and using the Canon proprietary signaling system. You'll have all the eTTL goodies, but unlike radio, you'll be range and line-of-sight limited. If you're on an astronomical budget , you could always add RadioPoppers to remove those limitations.

One more word. Cactus V4s are terrific, but you may also want to consider the Yongnuo RF-602 triggers. They cost the same as the Cactus V4s, but can also work as a shutter remote and can wake up your flash, and they're at the 2.4GHz frequency the Cybersyncs use, rather than the 433MHz of the Cactus V4s. This basically means they don't need external antennas, and they're legal in more parts of the world . Also, radio interference seems to be less common. You run the same build quality risks as with the V4s, though. I decided to go for the YN RF602s, rather than the V4s, since I needed a new shutter release remote anyway when I moved to a 50D, and I've been pretty happy with 'em.

[reactin6]

excuse me, but where can I find those Yongnuo? tried amazon, ebay and nothing

[inkista]

Do an ebay search on (RF602,RF-602). That pretty much nets the ones being listed. Or you can just go to the eBay store for hkyongnuophotoequipment.

I would recommend researching anything on the Strobist Flickr group discussions, first, before buying so you'll know what you're getting into. The one big drawback of the RF-602s is that they can't take a sync voltage over 12V. So, they're ok with most Canon EXs and Nikon SBs, but older or manual flashes might fry 'em. The V4s, as I understand it, can withstand much higher trigger voltages on the hotshoe.