Slave Q&A: Your Questions from Last Week

After the two posts on slaves last week, there were lots of tips being shared in the comments -- and some good questions, too.

Answers to the latter, after the jump.
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‪Diego‬ (and several others) asked:


David, I've had some problems in the past with pre-flashes fooling the optical slaves causing the flashes to fire before exposure. Have you experienced any of that?

Yep, sure have. Especially when using my Canon G11 to sync with slaved SB-800's. The trick is to use the triggering flash in manual mode to eliminate the pre-flashes that are setting off your slaved flash too early. And if you do not want the triggering flash to contribute to the photo, turn it down as much as possible and/or block the light in a way that will allow your other flash to see it -- but not the area inside your frame.



‪Scott‬ asked:

I bought two high-end Wein optical slaves (the ones with the integrated hot shoe) two years ago and now they do not work. I suspect user error, but I am not sure what it is I am doing wrong. Could the level of the batteries in the flash affect the trip point of the slave? Does the optical device age and sensitivity drop over time?


Scott, I have never heard of that kind of aging, and at two years I would not expect it. And I am almost positive the batts in the flash would not affect the slave. I would contact Wein about your slaves. They have a very good reputation for quality gear, and I would bet they will run down and/or fix the problem for you.



Moishe at Midwest Photo noted and asked (echoing the woes of many Canon users):

Finding a slave that is compatible with YOUR flash can be very very tricky. This is one of those areas where you will be very well served to search the discussion groups on Flickr to find actual user experiences. You can NOT rely on compatibility published by the various slave manufacturers / distributors.



I am yet to find an optical slave that works reliably with Canon flashes. I've tried Fotodiox, several styles of Wein, Dot-line, Nisha and a couple others I can't think of right now.

Some of those work some of the time. Some work with some flashes but not with another identical model. If anyone has any recommendations on slaves that work with modern Canon flashes, please email me. Would love to carry them in our store!




Suggestions? Email him at moishe at mpex dot com.



‪Charles Verghese‬ asked:

I wonder if these optical slaves can be DIY'ed into functioning as a Lightning trigger? Without thinking it out through, I am of the opinion that it could be soldered onto a camera trigger cable. Reason I am asking is because I am trying to avoid having to pay the big bucks for a traditional lightning trigger.


Well, Charles, there is good news and bad news.

First, the bad news: I have never been able to get a slave to remote trigger a camera, and I have tried several models. I am not absolutely sure, but I think that the devices that will remote fire a camera both use relays and complete the circuit for longer than a slave does. Whatever it is, it does not work.

The good news, from someone who has shot a lot of lightning: You do not need a lightning trigger. First, lightning exists for longer than you think. Use a tripod and a cable release and you can do pretty well if you are fast on the draw when you see the lightning. Better yet: Use long exposures and cast a bigger net (time-wise) for catching the strikes.

You can also keep the shutter open (as long as your camera stays below the noise/time threshold) and block ambient with a black card held in front of the lens. That's very quick to move when lighting strikes, and you won't jar the camera, either.



E‪do‬ asked:

Is it ok to use PW in master flash & trigger the slave using the master? Are we going to have synch issues?


Edo, that depends on your flash and, more likely, your camera. The good news is that slaves add almost zero latency to the process. They are very fast circuits. That said, I have run into problems specifically with Canon 5D's and slaved flashes. The problem is that as slow as the 5D sync already is, they cut it awfully close on the second curtain. I am convinced that many 5Ds (Mk 1 and II) cannot reliably get a full, off-camera sync until you open them up to 160th.



‪Outofnapkins‬ asked:

I have run across the "standard" H-prong connector on the Wein slaves before, back in my old medium format film days. I had inherited a sync cord for it but didn't know what it went to until today.

For the life of me, I can't figure out when you could use one of those today without that dang cord. Would you mind including a section on the various slave connectors?


Actually, many big flashes used to use the HH sync cord plug. Even my old Vivitar 283's had aftermarket "Holly Flash Foot 1" metal feet that converted them to household sync. It is a cheap and rock-solid method, but pretty over-engineered.

There are way too many connectors to go down the road of listing them all, and to very little benefit. My suggestion is to get on the 1/8" (3.5mm) Sync Jack Bus. It's air conditioned, with comfy seats, wi-fi and a big screen TV. You'll love it.



‪Laird‬ asked:

I love the convenience of Wein Peanuts, being small and plugging right into Vivitars, but have a unusual problem. I use PW to trigger a SB800, and slave other flashes off that. Sometimes, the Vivitar slave doesn't sync at 1/250 and I have to drop down to 1/160 or slower. Other times they're fine.

I use Nikon D300 in manual (not TTL) and no rear-curtain sync. Seems to be unique to Peanuts, as I've not had this happen with "off brand" slaves that slide on the hot shoe. Any ideas?


Wow. I dunno. For one thing I would suggest PW'ing the Vivitar and slaving the SB-800 via its excellent, built-in slave. That will get you two reliable lights firing at full sync, at least.



‪Ad‬ offers the following tip:

When shooting with optical slaves or CLS in cavernous environments which are tricky to get the slaves to fire (gymnasiums, theatre) I aim the flash forward on the light standard and place an umbrella behind it to act as a surface to bounce the PW'ed flash master off. The umbrella is not used to soften the light, its simply used to catch and reflect back the master onto the slaved light.


Yep. Looks like the parabolic antenna on the Death Star and works great. You can also use sheets of paper or aluminum foil to do the same thing in a pinch.



‪Catherine‬ asked:

I recently bought a Canon 580 EX II and have learned from the comments in this thread that it doesn't have a built in slave. I'd intended to get the Canon 430 EX II in future to use as a second flash, and some Pocket Wizards Plus IIs to trigger them.

If I attach one PW+2 to my hotshoe, and the other to either of the Canon flashes, does this mean that I'd need another PW to attach to the other flash, because the two flashes can't 'talk' to each other?


Catherine, in theory you should be able to slave the 430 (using a slave with hot shoe adapter cord) but as you may have read above some Canon flashes can be really picky with slaves. I would call Midwest and/or Flash Zebra for help with that.

On a broader note I would say that as a Nikon shooter, I have frequently been jealous of many of the Canon digital bodies over the years. That jealousy has never extended to the Canon flashes, for a variety of reasons. Several people have asked for specific advice about the Canon eTTL system, and how to set up master and "slave" flashes with that optically based system.

Alas, I am so in-the-dark on Canon's light-based off-camera light system that I would be doing a disservice if I tried to explain it. There is a new book by photographer N.K. Guy, entitled "Mastering Canon Flash Photography," which is a sort-of lighting compendium told from the Canon flash perspective that may be of more specific help to you.

It is not a purely Canon book, but rather as small-flash lighting book with a strong Canon orientation. If you are in the dark on your system's capabilities, it may be of help to you.