Pavel Kolpakov

Z240 performs just a mono flash, it cannot produce FP flicker 40 khz. Camera shutter window must be fully open at the moment of mono flash, to get uniform exposure along the shot. Nikon mechanical shutter fully opens window maximum at 1/250, not faster. That is why 1/250 is official "sync speed". If user sets 1/320 ... etc., the window never fully opens, it looks like an open strip going along the shot (rear curtain becomes visible on the picture), and it needs FP flicker long flash then. So, shooting by Nikon with underwater strobes, user must set only up to 1/250 speeds, to get uniformly lighted picture. Yes, 1/320 is threshold value, dark strip is slightly visible (or almost invisible) on some Nikons, but anyway, it is not recommended for common case.

This is truth, Inon FEC algorithm via Z240 / Z330 right dial switch is effective not for all cases. Synching by pop-up flash, the effect sometimes is small or invisible. But, if you use any Optoelectronic TTL-Converter for Z240 / Z330 synchronization, you see that Inon FEC (right dial switch) really adjusts +/- lighting. This is because of LED's clear square signal shape, Inon FEC algorithm process it much better than analog flash signal.

Yes, Retra new strobe is announced as HSS. We are waiting for it to make TTL tests. When HSS strobes appear on the market, TTL circuitry manufacturers can make HSS feature in firmware.

Thank you for kind words guys! I am happy to help when i can.

Thanks for the info guys!

Good job! And good idea! Please advice, where did you buy that transparent spare part? I also need it. By the way, UW Technics is developing now TTL converter for Seafrog A6xxx housings. It's LED board is purposed for installation on this transparent part (inside the housing). TTL converter has LED and Electric outputs, as usual. So, you could more easy use both type connectors (Optical/Electric) on your A7RIII housing, using that transparent part you has installed and Nikonos bulkhead simultaneously.

I sent you few suggestions by messenger. Please look.

The concrete strobe YS-D2 sample may be a problem, who knows. Try to change the strobe, just for test. Let's contact in Messenger, I think i know how to solve your setup problem anyway.

Hello Joss, Only Sony plays that game with sync speed (1/160 >> 1/250). Nikon D500 has fixed max sync speed 1/250. This is simply a speed of Nikon mechanical shutter. Impossible to improve it by this way, The only way to use high shutter speeds for D500 is to use HSS underwater strobes (if appear on the market), which can produce 40 khz flicker long flash.

Nauticam product is manual trigger, it does not use communication protocol with camera. Max sync speed must be 1/160 for this case. Yes, the 1/200 can be used as a threshold value, small gradient begins at the top of image. But for 1/250 sync speed, you need any TTL device connected to HotShoe.

Here is the video:

UWTechnics ships Sony TTL Converter for Nauticam A7...A9 housings since 31-July. Maximum sync speed is 1/250, tested, no dark strip on images.

Subal must supply VR3 board only with "left" type HotShoe cable (cable is pointed left). But looking to user setup picture, i saw the "right" type cable there. User has to reconnect cable now to mirror position (rotate 180 degrees) on the board. It will not be so comfortable as proper cable ("left type"), but it will work. Here is assembling for such case:

If you cannot sync the devices, it exactly means that something is wrong in setup or settings. Any small detail or defect, which you maybe don't see. Ok, i will make detailed video after few days. It will help you. Sorry i am out of city till the end of the week, so i can make the video only next week. If you have possibility, try to change the concrete parts of the system, - strobe (first of all), FO cable, camera, to recognize the problem part. This TTL board can work with all Nikon cameras and most of underwater strobes. Don't worry, you will solve the problem, anyway. Many people use #26308 with Z7/Z6 for today, and everything works fine.