My NA6400 is equipped with the UWT board that has the Retra strobe with HSS selected at position 9 (I think it is from memory). But, I am (wanting to) shooting a Marelux Apollo with HSS. My initial experiment seems to indicate I am getting sync at least to 1/500.

I really do not understand the UWT board in regards HSS. I assume it is manual exposure when using HSS? I have an admitted knowledge gap here, actually, it is a chasm.

Yes, I have a UWT board and use HSS quite a lot but with Retra strobes.

The HSS setting is indeed Manual but that’s a setting on the strobe not the UWT board. The board needs to be set on whatever the correct setting is for Marelux. You then use the strobe controls to select HSS.

22 minutes ago, TimG said:

Yes, I have a UWT board and use HSS quite a lot but with Retra strobes.

The HSS setting is indeed Manual but that’s a setting on the strobe not the UWT board. The board needs to be set on whatever the correct setting is for Marelux. You then use the strobe controls to select HSS.

Thanks for confirming manual, that is what I thought but the instructions for the board are sometimes confusing. My UWT board has no setting for Marelux HSS. The only setting that supports the HSS is the Retra setting. The way my board works (?) is that when the A6400 camera shutter speed exceeds the native sync of 1/160 it goes to HSS mode. Yes, at that point the strobe must be selected then to HSS, this is a switch position on the Marelux. I understand the strobe must be set to HSS. Five years ago when I bought the NA6400 and the UWT board the Marelux did not exist ;). I am just trying to make do with what I have and play with HSS on a five year old rig for which I do not want to spend $$ on yet another trigger.

I do seem to be getting sync but I do not want to work the strobes but a few shots on my kitchen table. I think I am seeing a dark top above 1/500. I am just going to have to get it in the water. I do not want to risk damage to the strobes dry firing enough to prove or disprove functionality of the Retra board setting with the Marelux set to HSS. :)

A curious thing, leaving HSS behind just for a moment, UWT board set to 0 (position for manual), by turning my A6400 off, turning it back on and then selecting WL off and set shutter speed to 1/160 and then selecting WL to on the shutter then defaults to 1/200 and syncs just fine and it sticks even if I turn the camera off and back on. But, if I change the shutter speed to another value my maximum speed with flash is then only 1/125 (yep, not 1/160), so I have to reboot, select WL off, set shutter speed to 1/160 and then go WL to on and voila, 1/200. Weird but useful to help control bright background, gains about a 1/3 stop I guess. I do not know if that little bit of extra shutter speed trick works with other Sony cameras and the UWT board but it does with mine. And yes, the photo data confirms 1/200 speed.

James

Edited August 29Aug 29 by Nemrod

Hi Nemrod

I'm no camera sync expert - Pavel is The Man (the UWT Man) - and I'm sure will chip-in.

Agreed on not kitchen table-testing, but if you have a bath or even a decent size sink or tub you can fill with water, you can always try the strobes in that. That said, if you are getting that dark band above 1/500 that does sound like a sync issue. I can fire at 1/2000 with HSS and have no problem.

Pavel?

I guess my question is, congealed down, what differs between HSS on a Marelux or HF1 or any other HSS capable strobe that is different from a Retra strobe such that using the Retra position on the UWT board (that does not have a HF1 or Marelux position) would not work and sync?

I can guess that the output profile/curve is different but that should affect TTL only and the HSS as confirmed by Tim is manual. Is it the number of flashes or the sequence of flashes that may differ between a Marelux HSS, HF-1 HSS and Retra HSS? That could explain why I might be seeing a dark band (unconfirmed at this point) above 1/500.

I am not complaining about the trigger or the strobes, I am trying to understand how it works and why different brand specific profiles are needed on the trigger?

Edited August 29Aug 29 by Nemrod

Hey @Nemrod

Regarding the UWT and HF-1s, yes they are HSS compatible…kind of. (I use this setup)

Yes, HF-1s do HSS, but there is no real on-strobe power control to dial them up or down while doing HSS. They will sync with high shutter speeds, but the overall amount of light in the scene must be controlled via camera settings. (ISO, shutter, aperture) Adjusting the power knob in HSS has no impact on the light power.

So far, only the Backscatter trigger will allow power control on the HF-1s in HSS. It’s a little quirk with an otherwise solid package.

Retras appear to consistently have the best experience with UWT triggers, but there is the price delta.

Hope this helps,

Chip

Edited August 30Aug 30 by ChipBPhoto

Hey Chip

Sounds like you don't have that dark band issue that Nemrod is getting?

Tim

Admittedly, I don’t use HSS very often due my camera’s 1/400 ability. But the times I’ve used it, no I have not noticed it.

On 8/29/2025 at 4:40 AM, Nemrod said:

I guess my question is, congealed down, what differs between HSS on a Marelux or HF1 or any other HSS capable strobe that is different from a Retra strobe such that using the Retra position on the UWT board (that does not have a HF1 or Marelux position) would not work and sync?

I can guess that the output profile/curve is different but that should affect TTL only and the HSS as confirmed by Tim is manual. Is it the number of flashes or the sequence of flashes that may differ between a Marelux HSS, HF-1 HSS and Retra HSS? That could explain why I might be seeing a dark band (unconfirmed at this point) above 1/500.

I am not complaining about the trigger or the strobes, I am trying to understand how it works and why different brand specific profiles are needed on the trigger?

Agreed, the dark band is likely a sync issue. I’m HSS curious, too, and I’m slowwwwly working my way towards that as I have an UWT trigger and a slow-synching A7c and A6400s. I’m about to pull the trigger for Retras. Inon has been too slow to the game. And I wouldn’t mind the HF-1 but would have to change triggers.

How these triggers talk to strobes, and vice versa, seems a programming issue. Or a co-branding issue. Or a licensing issue. Or a money issue. Maybe all four? This falls into the Stuff That’s Good to Know, which we can switch off if it’s too painful to learn.

47 minutes ago, humu9679 said:

And I wouldn’t mind the HF-1 but would have to change triggers.

Probably misdirecting my thread as I oft do others, my apology in advance. But, this is kind of part of what I am asking. Why do you have to change triggers?

The Retra strobe HSS function is manual exposure only?

Are there any strobes and cameras that can perform HSS strobe in TTL? And thus use the internal camera strobe exposure compensation to control the strobe, where for example, the HF-1 (and possibly the Marelux?) have not functionality for exposure control on the strobe power knob in HSS and possibly in TTL?

I am half way smart technically, and apparently some of this is more than half way confusing, to me :(. I am I suppose making this too broad. But feel free to discuss manual/auto TTL :) with popular strobes.

(I feel you on the Inon, I give up. And since I have a new set of S220 strobes, I want to supplement the S220s with something GN36+ for big animals and reef scenics). HSS is not a requirement. I have three working camera rigs and only one is HSS capable, my NA6400, the NA-R50 is not and neither is my little Canon/FIX S90.)

I don't know how complicated it would be to enable TTL with HSS but I do wonder why you would bother. Manual exposure with strobes isn't difficult - far from it - and using HSS doesn't make a great deal of difference, if any.

5 minutes ago, TimG said:

I don't know how complicated it would be to enable TTL with HSS but I do wonder why you would bother. Manual exposure with strobes isn't difficult - far from it - and using HSS doesn't make a great deal of difference, if any.

Because many folks shoot TTL and it is useful sometimes if not all the time :). And because as discussed here, the HSS function with the HF1 (and possibly Marelux and others?) do not allow power adjustment via the power knob on the strobe in HSS or TTL ( @ChipBPhoto )? If that is true (?) then there is no way to control output in manual. But one could control output via the camera strobe exposure compensation if shooting in TTL. That is more of a question than a statement.

As well, many Sony cameras do not have a preflash cancel or a flash manual mode, they always fire a pre-flash. In manual strobe mode the strobe must be configured to ignore the preflash. Or use the preflash and run TTL. Or use a trigger like the UWT that has a manual position that via board software ignores the Sony preflash (0 on my board).

Edited August 30Aug 30 by Nemrod

LOL, please, nobody take this as a complaint on anything, camera, board, strobes. I am just trying to work with what I have. I have a five years old Sony A6400 in a NA-6400 Nauticam housing with a UWT board purchased at the same time and the only position on the switch board that does HSS is the one designated for Retra strobes. I have Marelux strobes available for my use and they have HSS capability.

I am not going to purchase another $$ expensive board that has other HSS support. I do not think I can afford Retra strobes. Therefore I was playing with the HSS Retra board position with the Marelux strobes in HSS mode.

What I have found and currently think is with very limited use on my table and will not be able to verify further until I can get in the water (so as not to damage these super nice Marelux strobes :).

1. I am using the UWT board in the Retra position. I do seem to get sync, at least to 1/500 above which I think I see a band or dark top edge on the test image.

2. I do not think the power knob is functional in HSS mode or TTL mode. The strobe power knob is functional in Manual non HSS mode. The Sony A6400 seems capable of controlling the Marelux strobes in TTL mode and I can vary strobe power via the camera flash exposure compensation but the Retra HSS (?being manual only?) I cannot control output either on the strobe or in the camera menu.

3. I think this would be similar to the HF-1 having the same issues. (Yes Backscatter has a HF-1 specific trigger which I am not going to purchase and I am using Marelux strobes for the moment).

4. I assume, perhaps wrongly, that current UWT and other triggers do have positions for Marelux, BS HF-1 and other similar strobes in addition to the Retra and support HSS function and strobe output if only via the camera?

Edited August 30Aug 30 by Nemrod

There are lots of position on the dial on your UWT trigger as there are lots of ways to do TTL and each camera manufacturer has it's own way of doing it and requires a different trigger board and each strobe manufacturer has adopted different timing etc for their TTL as there are a number of ways to do this and each style of TTL has its own position on the dial.. Pavel had a post on this a while back. This is just on getting TTL to work before worrying about implementing HSS. This is made more difficult as in general it is done of fibre optics and with the possible exception of Olympus RC1 there is no dedicated handshake like you would get with a Nikon camera communicating to a Nikon strobe. Add to this, the TTL protocols are reverse engineered to work over fibre optics.

Your specific question I think is best answered by Pavel, I would send him a PM.

On your question, a black band means it is not syncing properly, there could be any number of reasons for this. If you look at the instructions for the latest current UWT trigger here:

Google Docs

#11071-HSS-SONY-A7-June2024.pdf

you will see that Marelux has a separate dial position including HSS, so it appears it uses different protocols. I would suggest that given you can use up to 1/400 it would seem, that this is better than your camera's 1/160 and just work within that limitation. Controlling output in HSS can be done by changing shutter speed, aperture and ISO. so to get your exposure right you can juggle all three of these. As you increase shutter speed the exposure from HSS will reduce as it acts like a continuous light source.

Probably the best way to proceed is to start with your current settings and adjust the shutter speed up and ISO up to keep the background exposure constant and do some test shots.

Hah! Maybe he can reprogram my trigger board ;).

Please, I am not being serious, I would not expect to be able to reprogram an old board :).

Also the new products need to be send back to make software updates if needed.... :(

6 hours ago, Nemrod said:

Hah! Maybe he can reprogram my trigger board ;).

Please, I am not being serious, I would not expect to be able to reprogram an old board :).

I wouldn't necessarily rule that out. As Chris suggested, drop Pavel a PM and explain the issue. He's really helpful.

22 hours ago, Nemrod said:

Probably misdirecting my thread as I oft do others, my apology in advance. But, this is kind of part of what I am asking. Why do you have to change triggers?

The Retra strobe HSS function is manual exposure only?

Are there any strobes and cameras that can perform HSS strobe in TTL? And thus use the internal camera strobe exposure compensation to control the strobe, where for example, the HF-1 (and possibly the Marelux?) have not functionality for exposure control on the strobe power knob in HSS and possibly in TTL?

I am half way smart technically, and apparently some of this is more than half way confusing, to me :(. I am I suppose making this too broad. But feel free to discuss manual/auto TTL :) with popular strobes.

(I feel you on the Inon, I give up. And since I have a new set of S220 strobes, I want to supplement the S220s with something GN36+ for big animals and reef scenics). HSS is not a requirement. I have three working camera rigs and only one is HSS capable, my NA6400, the NA-R50 is not and neither is my little Canon/FIX S90.)

I did have an HF-1 in my hands briefly to try out HSS with my UWT trigger a couple of years ago. And we know now how that was going to turn out. Only after looking more closely at a solution for my Sony’s sync speed issues did it become clear that each manufacturer creates its own mating protocols, etc. (some of us are to the left of bell curve). Anyhow, it’s also clear that trying to create protocols for TTL creates more complexity which can be tackled at a later date.

As Chris suggests, if you can get a 1/400th of a second sync speed with your current kit, I think I’d take the point and remain undefeated in the table.

On 8/29/2025 at 3:49 AM, Nemrod said:

My NA6400 is equipped with the UWT board that has the Retra strobe with HSS selected at position 9 (I think it is from memory). But, I am (wanting to) shooting a Marelux Apollo with HSS. My initial experiment seems to indicate I am getting sync at least to 1/500.

I really do not understand the UWT board in regards HSS. I assume it is manual exposure when using HSS? I have an admitted knowledge gap here, actually, it is a chasm.

I must admit that I used MARELUX Apollo III strobes with the UWT Retra dip switch position successfully in TTL and HSS before a converter appeared that had a dedicated Apollo protocol. You may want to get your hands on an Apollo S or Apollo III for that reason, maybe?

4 hours ago, Adventurer said:

I must admit that I used MARELUX Apollo III strobes with the UWT Retra dip switch position successfully in TTL and HSS before a converter appeared that had a dedicated Apollo protocol. You may want to get your hands on an Apollo S or Apollo III for that reason, maybe?

Thanks, I am just going to try it in a couple of weeks in Roatan and see what goes.

I am using (borrowing) Apollo S strobes. They are impressive kit for sure. How did you control the Apollo S strobe output in HSS?

On 9/9/2025 at 3:25 AM, Nemrod said:

How did you control the Apollo S strobe output in HSS?

It‘s called M-HSS for a reason 😉

But you will find leaving the HSS power dial on full for most of your shots, I suppose.

1 hour ago, Adventurer said:

But you will find leaving the HSS power dial on full for most of your shots, I suppose.

Yeah, I agree. I don't think I've ever turned down the HSS output. Usually it's shooting into the sun and you need as much power as possible to overcome the sunlight and illuminate something that's in the shady side.

The reason I am asking about power control in HSS is that I do not see any change between full and minimum settings. From that I concluded that the power knob is not functional in HSS mode on the Apollo S strobe? In a couple of weeks I can get in the water and play with HSS. Thanks.

40 minutes ago, Nemrod said:

The reason I am asking about power control in HSS is that I do not see any change between full and minimum settings. From that I concluded that the power knob is not functional in HSS mode on the Apollo S strobe? In a couple of weeks I can get in the water and play with HSS. Thanks.

I could be wrong, but wouldn’t the power control dial on the right would allow for output changes, even in HSS?

11 hours ago, humu9679 said:

I could be wrong, but wouldn’t the power control dial on the right would allow for output changes, even in HSS?

I do not know. I do not see any difference in my limited trials turning that power knob in HSS using the Retra board switch position. I do see that the Backscatter HF-1 only has one power setting in HSS and I suspect the same here with the Apollo S, excerpt from HF-1 manual attached. I have the Apollo manual and I do not see this addressed therein. I think I am beginning to understand HSS.

Edited September 12Sep 12 by Nemrod