I have a Canon EOS 6D and a Canon 430EX III-RT flash. I want to sync my flash to my camera unmounted (which doesn't have a built in flash for me to use as a master). Yet I don't want to spend around $400 on a speedlite transmitter. Are any other options possible?
Well, you have basically few options:
- use other flash unit to sync with (which would have to be attached to your camera)
- use off-brand remote flash trigger which is cheaper
- use a cable cord to trigger your flash (something like this https://www.ebay.com/itm/DSLRKIT-3M-3-meter-E-TTL-Off-Camera-FLASH-sync-Cable-Cord-for-Canon/252337506581?hash=item3ac07cc915:g:ihEAAOSwxp9W-4Lk)
Unfortunately 6D can't trigger flashes remotely on its own.
The Canon 90EX is the smallest of the Canon Speedlights, and it can work as an optical master. It's so small that it easily fits in a pocket.
With a 90EX mounted on your 6D, you can set your 430EX III-RT to optical slave mode. When you take a shot, the 90EX will fire before the shutter opens to send the command to the slave, but it won't fire during the shot. (Other optical master units can send commands and also fire during the shot, but the 90EX is so small that it doesn't have enough power to do both.)
cheap: A new 90EX lists for $149 and generally sells for about $99, but you can find used ones available for $25 or so. Used as a flash, the 90EX is so underpowered and gets so few shots out of its AAA battery that I'll bet many users quickly decide to trade up.
works: Used as an optical master, the 90EX fires at lower power, so gets reasonable life out of its battery. It's a genuine Canon Speedlight, so there should be no compatibility issues between the 90EX and your other gear.
integrates nicely with the 6D: The only control on the 90EX itself is the power button, but the 6D gives you all the control you need. You can set up flash groups, change the power settings for each group separately, use High Speed Sync, etc.
optical: Triggering your flash optically works, but it doesn't work as well as radio, which is why Canon is switching to radio in the first place. Using the 90EX will work, but it brings the drawbacks of optical triggering with it: you need line of sight between master and slave, it works better indoors than outdoors, etc. It's nice that the 430EX III-RT can fall back to optical slave mode, but sort of a shame to not take advantage of radio triggering since you've got it.
turns off: The 90EX automatically turns off after about five minutes to save power. You're supposed to be able to disable that behavior with a custom setting, but I've had some trouble getting that to work.
The 90EX isn't a perfect solution, but it's not bad, and if you buy one used you've got a very inexpensive way to get into off-camera flash. And it's nice not to have to carry a long E-TTL cord around or have one hanging off your camera while you're shooting.
There are a lot of different options including cables, and add-on optical and radio triggers. (See: What should I look for in a wireless flash trigger for a home studio?).
But Canon has built in both a "smart" TTL optical and a radio-based triggering system into its "-RT" designated speedlites. So, using one of those two systems is likely to be the easiest way to go with the most features.
You could get an optical master unit to use with the 430EX III-RT in optical slave mode. (See a list of the possible master units here: Is there a Canon equivalent of the Nikon CLS?).
But optical slaving has a few drawbacks. It can be overpowered in sunlight, and it requires line-of-sight (the red panel on the front of the 430EX has to "see" the master light pulses). You can't, for example, put a solid object between the on-camera master and the slave flash. Which is why there is radio slaving.
To use a Canon -RT master, you need a master unit, and the Canon 600EX-RT speedlites and the ST-E3-RT are not your only options. There are quite a few 3rd party alternatives:
- Yongnuo YN-E3-RT transmitter
- Yongnuo YN-600EX-RT, and YN-600EX-RT II
- Yongnuo YN-686EX-RT (has a li-on battery pack)
- Phottix Laso transmitter
- Jinbei/Orlit TR-611 transceiver
Just keep in mind that if you use the Canon -RT system, that, unless you use the Jinbei/Orlit or Canon triggers, so you can set off a Jinbei/Orlit RT studio strobes, you will be limited to speedlights.