Problem with strobe and Nikon z7 II

Hello

I have one Nikon z7II on isotta housing, with manual/TTL trigger I use two strobes, sea and sea ysd2 and 3, connected by fiber optic. I shoot fully manual.

My problem is:

in exactly the same conditions, when I take photos, the strobes fires, but I see the light of the strobes 50% of the time, in alternative. First photo will show the light, the one after no, then yes, no etc... The strobes fire everytime, but the camera seems not sync with them half the time.

Before photo that end up with strobe light on it, I see adapted exposure in the evf.So if I underexpose, I will have the dark screen. After shooting i can see the strobe light.

Before the photo that end up without the strobe light on it, image exposure is balanced to be correct, and I see a little orange thunder on the right bottom of the screen. So even if I totally underexposed, the screen will show me correct exposure image. I shoot, the strobe fire, but then on the photo, the image is fully dark, no strobe light on it.

And this alternate every photo

I made tests, try to change everything I can't find solutions. The strobes do fire, but exactly half of the photos are without it on it. It is like they are not synchronised with the camera. I made what is recommended in the notice for the strobes, they fire well

Any idea or suggestion ?

My first thought is that the strobes are not recycling fast enough. 

They may still pre-flash, but may not have recharged the capacitor enough to then provide greater power. How quickly are you cycling the camera?

Adam

Thanks Adam for your answer.

I thought of that in the beginning. But this doesn't change the problem. If I wait one hour that is the same

The strobes say that they are ready to fire, and they do

I think this comes from the camera or trigger 

The camera behaviour change, alternate with two modes, one with real exposure, no flash logo on it and other mode not rela exposure and flash logo on.

The flash light will be seen on the first mode, not on the second

What happen when you fire the strobes in manual mode?

Camera/strobe and flashes all set to manual...

Remember flash sync speed in 1/200

The strobes are in Manual mode and they fire 

I fully shot manual

Yes I changed from 1/200 and under, doesn't change

Here are some quick photos of the screen, to show the two "différents modes" the camera produce, without I touch anything 

It always alternate between this two.

So first it will be like on the first photo, with exposure correction, and you can see a orange thunder on the bottom right. With this mode, even if the strobe fire, it will not be seen on the photo 

Then after I took the first photo, it will alternate with the second photo, where the screen doesn't compensate low exposure. The orange thunder is not on the bottom right. I shoot the photo and the light will be seen on the photo

Then it will come back to the previous mode and etc...

The screen shows you are using rear curtain sync,  your trigger/strobes  may not support this, so maybe try without that turned on - instead try fill flash .    What modes are you using on your flashes - I believe there is manual with and without pre flash - try both of them.

Also assume you have set flash to manual? 

Which trigger are you using?

Hello 

Thank you for answering

I tried without rear mode, that is exactly the same.

I have TTL/ manual trigger provided with the housing.

Strobe I tried on TTL and manual that doesn't change anything. Pre flash mode doesn't work. The strobes strike every time on manual or TTL mode, but like is seen only half of the time on the photo

What I don't understand is why the camera change behaviour every photo like on the photos?

Wow, annoying. Is it possible your hot shoe sync cable is faulty or not firmly plugged into the hot shoe? Or trigger?

If it is doing the exact same thing every single time it seems to me that there is a problem with how the trigger is interpreting the signals from the camera.  Loose connections and other problems like that should not be able to produce such perfectly repeatable phenomena.

Just to clarify your rear screen shot 1 shows the flash ready orange lightning bolt.  When you press the shutter release, the image has no flash illumination.  You say even if the strobe will fire - does the flash fire everytime or only sometimes?   I also assume if they fire both strobes fire?

Screen shot 2 with no flash ready - the screen is dark when you take an image the strobes fire and the strobes sync correctly.

Some things to check:

• set the shutter speed to a low speed maybe about 1/2 sec and use rear curtain sync and manual flash set in camera
• observe the LED in each case above to see if it lights once or twice - this checks if the camera is emitting any pre-flash
• If you have a Nikon speedlite set it up in manual flash mode at minimum power and hold the fibre optic to the flash and try again to see if it triggers all the time or every other time like you are seeing with the flash trigger.  Use manual flash  in fill flash mode.

If you can get normal triggering with the speedlite to me this means the problem is in the trigger.  If you can't get it to work with the speedlite the problem is in camera settings or the external strobes.

It seems you have the strobes configured for preflashes. They only fire on the second flash. 

Hello 

Thanks you all for trying

Couldn't answer before because I was in the sea. 

Isotta called be by video to find solution. 

The problem was coming from the fiber optical wires that were only mono canal 

So we fixed the problem on the TTL 

Thanks Isotta, incredible service, it is rare, such a company