DirtFarmer Loc: Escaped from the NYC area, back to MA

But it was triggered by the speed light

BebuLamar

Yes and the problem was because he had it on TTL.

ELNikkor

I'm with those who say you are not getting ANY flash on your subject at all, just the ambient or modeling lights. Easy to check, just take a shot without tripping the flashes and see if the exposures are the same as when the flashes fire; then you will know it is a synch problem. (Does your camera have a "FP" flash setting? That would have the flashes going off before the shutter opens to accommodate a flash-bulb.)

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

The speedlight emits preflashes to measure the light when in TTL mode - then it flashes the correct lighting - but the optical slave is very sensitive and will trigger the monolight before the exposure actually happens. As others Bebu, Thomas and others suggest - this is most likely the issue.

BebuLamar

The OP confirmed it here
"Yes I googled it and I had the speedlite on ETTL. The preflash was tripping the studio lights and then when the shutter opened the studio flashes had not yet recharged.

I put the speedlite on the hotshoe set to Manual and that solved the problem.

I knew it was something stupid. I've never tried to use a speedlite before. I always used a pocket wizard.

Thanks Thomas and all!!"

lamiaceae Loc: San Luis Obispo County, CA

I don't know your camera but the typical sync speed should be 1/125 s, 1/160 s, 1/180 s, 1/200 s, depending on model. My Pentax K-5 synchronization is max at 1/180 s. Slower than that and you add ambient light. I would also suggest setting camera and monolight to Manual as well.

amfoto1 Loc: San Jose, Calif. USA

You mention using a Speedlite as the trigger... with the monolights as slaves.

Do you have the Speedlite set to ETTL? (Auto exposure flash)

If so, that's probably the problem.

ETTL actually causes a portable flash to fire twice: First it fires a low powered (1/64) pop or "pre-flash" that the camera meters to determine the power needed for the second, full powered flash. These two flashes happen so quickly that it seems like a single pop to us.

What happens with optically slaved strobes in this situation is they fire in response to the first, low-power pre-flash, before the properly synced full power flash. In other words, the big strobes that are supposed to provide most of your lighting are going off too early, before the camera's shutter has even opened, and not contributing any light to the image. The result is massive under-exposure... only the on-camera flash "master" is providing any illumination to the subject.

There are at least two ways to solve this problem....

1. If you must use the Speedlite to trigger the strobes, take it out of ETTL mode. Switch it to Manual and turn the power way down (if you don't want it to contribute too much to the image). You'll have to experiment with the power level of the Speedlite. It needs to be enough to reliably trigger the slaved monolights, but not so much that the Speedlight becomes the primary light source (unless that's what you want).

2. Use something else to trigger the monolights and don't use the Speedlite at all. You can either use a PC sync cord or some sort of wireless trigger to trip one of the monolights, while leaving the other monolight(s) set to slave mode. They will be tripped when the first one fires. This is usually the better solution, because the Speedlite isn't on the camera contributing some light to the overall exposure (unless that's what you want).

The above assumes that there is no one else around you shooting. One problem using strobes or flash with an optical slave is when other photographers are firing flashes in the area, causing the slaved strobes to fire. Then you only get the primary strobe firing, the one that you're triggering either wired or wirelessly. The result is very lopsided "incomplete" lighting. (Don't ask me how I know!)

BTW, when I use my strobes I always try to set them all to 1/2 power so they will recycle much faster. To do this I need twice as many lights or twice as much exposure with the camera (one stop larger aperture). However, even doing this the recycling isn't fast enough for the strobes to be recharged and fire properly when ETTL makes that second, full-powered pop.

Sync speed with 5D Mark II for portable flash is 1/200. However, with most strobes it's slower. OP's 1/125 is sure to be fine. With my particular monolights I've used up to 1/180 with full frame Canon without problem (with APS-C and 1D-series that have 1/250 flash sync, I can use 1/200 with my monolights). The reason for this is that most strobes fire more slowly than portable flash do. Most strobes also do not work with "high speed sync", either (which allows Speedlights to be used with shutter speeds faster than the camera's flash sync speed, but at the cost of greatly reduced flash reach).

WOKE WARNING: We're not supposed to talk about "master" and "slave" flashes and strobes any more. Those terms irreparably traumatize some of the snowflakes living in our overly-sensitive society today. Canon, for example, has changed the terms to "sender" and "receiver" in all their flash and camera manuals produced since 2017.

bobfitz Loc: Kendall-Miami, Florida

Was your exposure compensation set to -5?

BebuLamar

He can set the exposure compensation to -5 and the exposure is still right. The flash doesn't care about what setting the EC is. The flash just fires before the shutter open due to the pre flash from the hot show flash used for triggering.

Randyfrieder Loc: Long Island, New York

Hi, most monolights, offer two slave modes, one is for responding to a trigger flash, that doesn’t have a “pre flash” the other, for if it does.
You may be set to the wrong slave mode, and the monolights, may not be firing at the correct time. That would make them look like they are firing, but the shutter will not be open at the right time to “see” the flash output.
You can try a different slave setting, slave 1 or slave 2.
Or even try a pc cable directly attached to the monolights, to see if this helps.

frangeo Loc: Texas

Studio lights, shoot manual. Flash meter would help.

fotoman150

Changing the flash to manual stopped the pre flash. All is well thank you.

bebop22 Loc: New York City

I agree - disable all automation. Do everything manual and you won't have problems.