Looking for a reliable optical slave

Rylee Isitt · Post by **Rylee Isitt** » Wed Jan 01, 2014 6:30 pm

I've been attempting to find a reliable optical slave. By this I mean the little "eyes" that fit to the hot-shoe of a flash, as opposed to the studio strobes. My idea of reliable in this situation (indoor multi-flash setup with focus stacking on a table-top) is 100%, not a single flash missed after hundreds of exposures.

At first I tried cheap imported units from eBay, which were very unreliable with about a 60% chance of firing. Then I tried the Optex branded ones, which I thought would be good, but as far as I can tell they are no better. I know the flash units are properly charged because firing them at mid to low power allows for a very rapid flash frequency, yet I wait many seconds between exposures (plus, the charged indicator lights remain lit).

I am aware of the "SCR lockup" issue with Canon flashes, which I experienced as well. This alone can be a major issue for any Canon user, since the flashes will only fire once by optical slave - and must be decoupled or reset to allow the pair to work properly once more.

I migrated to manual Vivitar flashes after this, but was rather unhappy to find that while the SCR lockup issue went away, the optical slaves only worked 60% of the time, each.

A guy at one of my favorite camera stores said that Wein units are known to be good, but at this point - having tried two different brands and been rather unhappy with both - I am hesitant.

Anyone out there find something that works 100% of the time?

I suspect I will abandon the entire idea and start using PC sync cords for everything, at least for now.

Chris S. · Post by **Chris S.** » Thu Jan 02, 2014 2:10 am

Rylee,

I've never been a fan of optical slaving either. But neither am I a fan of running PC cords between camera and flashes.

What works well for me are inexpensive radio frequency (RF) triggers. The ones I use are Yongnuo RF-602 units, which cost very little. Having used these for tens of thousands of exposures, I don't think they have ever missed a shot. And they are dirt cheap. I do set the camera for a shutter speed of 1/160 second, a bit lower than its maximum flash sync. Doing this seems to avoid potential problems.

Radio triggers provide great freedom of flash placement with very little hassle. While such triggers used to be very expensive, at least some decent units are now very cost-effective.

Cheers,

--Chris

Rylee Isitt · Post by **Rylee Isitt** » Thu Jan 02, 2014 2:38 pm

Chris,

Thanks for your expertise here!

I was looking at the Pocket Wizard Plus X units the other day but don't like the fact that you have to still run a PC sync cord between transceiver and flash.

I have to admit I have a rather strong aversion to any cheap knock-off type product based on many bad experiences with such products, and Yongnuo's products seem to strike me as being a bit in that category. I've seen mixed reviews for their flash units, but this could just be that people with problems are more likely to leave reviews. But a good testimony from you after long-term use of presumably several of the units goes a long way to making me think I should give them an honest try. It still seems too good to be true, though... $40 seems a steal consider what Pocket Wizard charges for their offerings. There has to be a catch, right?

I notice the Yongnuo RF-602 units are made for specific cameras (for TTL metering compatibility, I suppose). If I get the Canon ones, will they still work with non-Canon standard hot shoe mount flashes fired in manual mode? I have four Sunpak 422D units with 12 V trigger and would love to use them, once I modify them to disable that annoying auto power off...

Rylee Isitt · Post by **Rylee Isitt** » Thu Jan 02, 2014 3:31 pm

Well a bit more research on my part and it seems like the answer is yes, the Yongnuo RF-602 should work with other flash units as long as I don't care about advanced features like wake-from-sleep, and various forms of TTL flash metering. Fine with me.

The trigger limit for them seem to be 12v. I've metered my Sunpaks at 11.7V to 11.8V depending on the unit. If they didn't mean for people to use 12 V trigger voltages, they'd have set their limit lower... so while I'm close to the limit, I think I'll be fine... I see people over in the flickr discussions have been pairing them with flash units that have 12 V trigger voltages with no issues.

They connect directly to the hot shoe. Great. They can fire my camera wirelessly too? Great.

Reviews are quite positive.

I think I'll give them a shot.

Thanks for the tip, Chris! This might be the winning solution.

Olympusman · Post by **Olympusman** » Thu Jan 02, 2014 3:50 pm

Optical slaves can be tricky. From the same manufacturer you may find some that work very well and others that are hopeless. Usually the issue is the trigger voltage of the flash. Most commonly, if the flash unit unit uses two batteries rather than four, the trigger voltage for the slave is insufficient. I had many customer interactions in which an Olympus FL-36 (two AA batteries) would not work with slaves but an FL-50 (which used four AA batteries) worked very well with the same slave.

Rylee Isitt · Post by **Rylee Isitt** » Thu Jan 02, 2014 4:24 pm

Hi Olympusman,

I'm using four-battery Vivitar and Sunpak units with 11-12 V trigger voltages. If anything that might be a bit high for the slaves? I don't know what their limits are.

I've got one flash unit with a 200V trigger voltage. Not sure if it would be any more reliable but I sort of stowed it away so that I don't accidentally connect it to stuff and go around damaging my camera gear!

I think Chris has fully convinced me to go with those radio triggers. They are cheaper (each) than the optical slaves!

Chris S. · Post by **Chris S.** » Thu Jan 02, 2014 5:20 pm

Rylee, sorry for the delay in responding.

As you’ve found, I don’t think the Yonguo RF-602 units are specific to a camera brand—at least in terms of triggering the flash. I haven’t used mine for remotely triggering the camera, but imagine that this function requires a different cord for Canon vs. other brands. Also as you’ve found, these units don’t support TTL or other advanced flash features. They just trigger the flashes to go off. They do perform this single task very reliably and inexpensively.

Before getting the Yonguo’s, I had a different set of cheap radio flash triggers that had no branding. They were about 98 percent reliable—meaning that for about 1 shot out of 100, the flash didn’t go off, and just about as often, the flash went off at some random time for no apparent reason. For my macro stacks, this was not a good thing. About one of every 100 frames would be black, with a similar number underexposed because a flash was not fully recycled from an uncalled-for triggering. But my Yonguo units have never had these problems.

You might want to lay in an extra CR2 lithium battery (which the transmitter uses), as it’s annoying to find it dead just when you want to shoot. These batteries last a long time in actual shooting, but if you leave your camera turned on after a shoot, you may come back a few days later to find the transmitter’s battery completely drained. (You can imagine how I know this.)

--Chris

Rylee Isitt · Post by **Rylee Isitt** » Thu Jan 02, 2014 5:58 pm

Chris,

That sounds fantastic.

I'd like to experiment with directional portait-style lighting for some subjects. So a key, fill, rim, and backdrop light. I can't imagine working with four flashes in stacks with anything less than 99.99% reliability.

I still don't understand how they are cheaper than optical slaves. Maybe because the optical slaves are more niche and so demand a higher price?

Chris S. · Post by **Chris S.** » Thu Jan 02, 2014 9:54 pm

Rylee Isitt wrote:I'd like to experiment with directional portait-style lighting for some subjects. So a key, fill, rim, and backdrop light.

Hear hear.

I can't imagine working with four flashes in stacks with anything less than 99.99% reliability.

Yep, multiple light sources--which I also use most of the time--do multiply the difficulty of any lack of reliability. This is one reason that I find myself relying on continuous light more and more for studio macro. Continuous light just works, with no surprises. (Assuming, of course, that vibration is not an issue--which is a big assumption.)

I still don't understand how they are cheaper than optical slaves. Maybe because the optical slaves are more niche and so demand a higher price?

Interesting question. Optical slaving is certainly an older, more entrenched approach, but it is inherently limited. For event photographers in situations where other photographers are on the scene, one's optically slaved flashes can fire whenever anybody sets off a flash, so RF triggers with selectable channels are pretty much the only way to go. And optical triggers operate on of sight, whereas RF triggers can work around corners and through flags and gobos--and at greater distances. The optical triggers I've worked with have gotten confused by bright sunlight, or even the light fluctuation caused by a person passing in front of the sun or window, or a hand thoughtlessly passed too near. With optical triggers, I needed to remember to keep the trigger pointing at the master flash. Yuck! To me, RF triggering is simply a more robust technology. So perhaps competition, in the past few years, has concentrated on it, and left optical triggering relatively unchanged?

--Chris

AndrewC · Post by **AndrewC** » Thu Jan 02, 2014 11:55 pm

Another vote for Yongnuos - at least on Nikon based. I don't use them per flash, as I use my own control electronics to set flash duration, but when I have used them to couple from the camera to the my flash driver I've never seen a problem.

Cost - probably because there are less "moving parts", though that is an outdated phrase. Most of the cost is in fabrication not raw material and an RF driver is very easy to manufacture.

Another system I've watched but not purchased are RadioPoppers which give full control but cost more.

Rylee Isitt · Post by **Rylee Isitt** » Wed Jan 08, 2014 3:12 pm

Chris,

Yup, I like the idea of continuous light as well. That Fostec FO illuminator works quite nicely and I have a four-way light guide for it. But I still like the idea of flash for some subjects - those that can handle the flash without moving about.

AndrewC,

Thanks for the second! I look forward to using them.

Not sure what to do with my optical slaves now, but I'm thinking of modifying one of them for use as a lightning trigger. I suspect all that's needed is to apply a specific voltage across the terminals and sense a voltage drop for triggering. In fact, since the shutter release port works the same way, depending on the voltage of the shutter release port of a camera it may be possible to almost directly wire the optical slave to the shutter release port.

SteveGreen1953 · Post by **SteveGreen1953** » Thu Jan 09, 2014 12:54 am

Personally, when working in a studio environment with stationary or slow moving subjects I much prefer studio strobes. They have considerably more power, consistent recycle rates, and there’s no worry about batteries dying. However, when capturing images of items being destroyed by my air-cannon the shorter burst of light provided by speedlites is required to stop movement. The shortest bursts of light are only accomplished at the lowest possible power setting of a speedlite, so typically multiple lights are required for an exposure with good DOF. If they are all the same make/model you might get away with “Y” splitter cables cascaded (I have fired four Canon 430exII’s wired in parallel hundreds of times with no problem.) But, a better solution (particularly if your strobes aren’t all identical) is something like this: http://www.dreamingrobots.com/store/ind ... he02zQtGN2.

I very much like radio triggers and the 602’s are fairly reliable at a great price. But, when I have only one chance to capture an image, a wired trigger is what I use.

The reason for specifying different flash manufacturers for the wireless triggers is the shutter half-press wakeup function. If your triggers won’t wakeup the flash with a half-press you might want to disable the sleep function (custom function 1 on Canon flashes if I remember correctly.)

You spoke about capturing lightning. The same guy mentioned above sells equipment for doing just that. A sensor is placed in the viewfinder of the camera, so the camera shutter only trips when lightning is in the frame.

Cheers! Steve

Rylee Isitt · Post by **Rylee Isitt** » Thu Jan 09, 2014 1:05 am

Hi SteveGreen1953,

Good info! I have built my own lightning triggers in the past using phototransistors and op-amps. Actually one of my first electronics projects was a lightning trigger. It works perfectly but looks suspicious and might raise concerns with airport security if I ever tried to travel with it. But it wouldn't be nearly as risky as trying to travel with the wired shutter release I built...

I'm usually more inclined to DIY than purchasing products like flash sync cable splitters and the Camera Axe. It's not usually any cheaper to DIY, but it's considerably more fun

But if I ever need to fly with this stuff, I'll probably find more professional looking products to avoid problems with airport security... as sad as that is it's a valid concern.