What is the reliability of slave systems?

I have been shooting with Alien Bees lights. I had a shoot the other week where a

series of photos came out underexposed and I think that it had to do with the slave

not firing. I was trying to creat strong side lighting and I had the key light directly to

the side of the model and perpendicular to the camera angle. The flll was an

umbrella set back by the camera and on its lowest setting. Judging from the

underexposed images, I must of had my sync cord plugged into the fill and was

depending on the slave unit in the key for its triggering. I think that the slave did not

trigger on the B800 key light some of the time, and that is the reason for the extreme

underexposure. The only thing that I can think of is that it was because the fill was

set so low, and possibly that the key was turned sideways with a very large softbox

on it, which might have blocked some of the flash comming from the key. Also, I was

using a black background, which I guess absorbed some of the fill as well. Does this

make sense? I was under the impression that the slave was VERY sensitive. The fill

was obviously bright enought or I would have noticed it not going off during the

shoot.

 

Can anybody offer any explanation? Should I run a wire to all of my lights? Can I

depend on the slaves?

if the light was firing intermittently than there are two possible culprits: the slave or

the flash units recycling time.<P>With the slave you have two potential problems: the

sensitivity and the possibility that the slave is 'blinded" by a previous flash for some

period of time, which might be dependent on the brightness of the flash that blinds

it, or some mechanical characteristics of the slave. Placement of the slave eye relative

to the light that does the triggering is also a crucial matter. A very sensitive slave

placed very close to a very bright light source (including the light emitted by the flash

to is attached to) may actually be blinded for longer than a slave "eye" with low

sensitivity. A good rule of them for overcoming these built in mechanical deficits is to

wait at least as long, but preferably 1.5x to 2x as long, as the unit takes to recharge

its capacitors when it is being used at full power.

It may also be the case that in some circumstances you are making images faster than

that flash can recharge and the flash simply isn't firing.<P>

As a rule I am not a fan of built-in slave eyes. One reason I cited above. Another is

lack of flexibility in positioning the slave, a third reason is modularity. I also don't like

hardwiring my cameras to lights and for that reason I use the wireless digital LPA

Designs Pocket Wizard system. This has several advantages , even in a small studio;

1.) the camera is now completely isolated from the pack or monolight in case

something goes horribly wrong and I get a big surge of voltage up the sync cord; I

can sync directly to my main (or "key") light for the set up, even if it is at a distance

from the camera;. it makes it easier for me to take accurate flash readings without

having to disconnect the sync cord for from the camera; and it is much more

mechanically reliable than hardwire sync cords (of course it is also a lot more

expensive, but for what I do time & concentration are money. I like the Pocket

Wizard's encoded digital system over infra-red triggering system because the IR

systems are just as prone to being blinded as a visible light system. I have also found

the Pocket Wizards to be far more reliable than the previous

radio remote triggering systems I owned.<P>In a studio

setting additional lights that need to be slaved are either triggered by additional PW

receivers or via high quality optical slaves from Wein, particularly the SS-XL series of

slaves. On location the "slaved" lights are always triggered via additional PW receivers

or transceivers.

Thanks Ellis. I guess I should hardwire all lights or spring for the PocketWizard.

I couldn't resist checking the range of the PW Multimaxs when I got two. I got reliable triggering and confirmations all the way down the block and through several houses and many walls, with the antennas mis-oriented (at 90 degrees to each other).

 

I'm wondering about your actual set-up and shooting style, tho'. If you're shooting so fast the key hasn't recycled when you fire the fill again, a PW or hard-wiring isn't going to solve that problem unless you can force a delay. The Max can do that, but I don't know about the other PW units.

 

I'd also suggest you check the ABs as they are with hard-wiring. You don't want to find out it's a problem with the AB after spending lots of $ on a solution to a non-problem. I haven't seen any rash of complaints about the AB's IR slave system being terribly insensitive, and indoors usually has IR bouncing around nicely. Were you shooting in a huge warehouse or some place like that?

Actually, I was in a small room, maybe 15x18. I think that it was the combination of:

 

1) the fill being on its lowest power

2) the key was turned perpendicular

3) the large softbox on the key, possibly blocking the sensor

4) the seamless black background absorbing the light

 

I should have plugged into the key light and not the fill. Maybe for the time being I will get the AB wired remote which will allow me to hard wire and control 4 lights from one location. I should be aware of these types of problems in the future and hard wire all lights if the situation looks like it might be necessary. I think I can rely on the optical slave for all but the odd situations. The remote will also come in handy for controlling lights that are out of my reach, such as high mounted hair lights, and background lights that might be difficult to reach. Monday I will call AB and see what they have to say.

 

Thanks for all of your help.

I like wireless radio slaves. But there is something robust about a Wein SSL, and it fits into small pockets, no problem. Simply put a 18" wire into the auxiliary slave connection, connect your slave--then point it line-of-sight to the triggering light. You can use sticky velcro to point it. Use only the sensivity you need, no more. A passing car with a chromed bumper in sunlight can trigger an SSL. So, have some XL's which are less sensitive than the SSL. Timber Borcherding timberborcherding