Seafrogs ST-100 Pro Underwater strobe - need your openion

Hi

has any one tested the Seafrogs ST-100 Pro Underwater strobe ? I am looking for reviews to decide whether to buy or not but I couldn't find any.

https://seafrogs.com.hk/collections/uw-strobe/products/st-100-underwater-strobe

Dealers say that this is Meikon company product.

https://meikon.com.hk/products/st-100-underwater-strobe

thanks, yes it is. they produce it under the " seafrogs" brand.

so, has anyone here actually used it ?

I tested the strobe recycle time, but have not had it underwater. Min power, 3.16fps. Full power 7 sec recycle time.

This is odd - I just received a pair of ST-100 Pros, popped in fresh-out-of-a-package, pre-charged Panasonic Eneloop Pros, hooked up the bundled fibers to my Sony A6300, and the recharge time is about 1.7-1.8sec (measured in 'full' mode, 'M' mode with power knob on maximum and 'S-TTL' mode with housing port covered), going by the extremely sophisticated method of a stopwatch app on my phone. Maybe it's different between wired and fiber optic sync? When I tested it in S-TTL mode with the housing port open, the recycle time was a fraction of a second, indicating that the camera dictated a much lower flash power (i.e. optical TTL does indeed work).

That is odd, but in a good way. In my setup, I used an AR7II and 5 pin Sea&Sea wired connection. Optical TTL was not available.

I'm not fond of the wired connection - two more O-rings to worry about and there's a lot of friction in the plastic threads of the retaining

nut at the strobe end.

You have an RX100 as well, right? Have you tried measuring recycle time when using optical sync with it?

Also, what batteries are you using? Strobe specs say 4s recycle time with NiMH and 5s with alkaline, but maybe yours have a particularly low discharge current?

I did experiment with my RX100iv, but the recycle time with its internal flash was so long, that I gave up that approach.

I'm using alkalines in my ST-100, but in my web searches, it didn't appear that the max current draw was significantly

different from the rechargeable types.

My comments about the cost of the Turtle notwithstanding, I was getting close to buying one based on email exchanges

with Balazs Kurucz at Turtle; but I couldn't verify that it would work with the ST-100 so gave up on that approach. It didn't

seem worth the $400 risk to get TTL considering that manual strobe could be more desirable.

In the meantime, I'm toying with the idea of getting a backup system based on the Meikon housing and A6300 (fo TTL) for a relatively

expensive, once only trip to Palau and Yap.

Ah, so it's quite possible that the batteries - particularly if they weren't quite fresh - were limiting your cycle rate. You might want to repeat your testing with fully-charged NiCD cells built for high-current applications.

If you want TTL, a Turtle trigger is a much less expensive (and compact! don't forget luggage space!) solution than an entire second rig. Meikon housing with 6" dome, A6300 and 10-18mm lens weighs 2.3kg without any accessories, and total cost, even if you buy used, is in the $1500-2000 range. As for backups, you already have an RX100 IV, which is a perfectly adequate backup camera - or a primary one, for that matter..

You're right, that Fantasea/RX100iv system is nicely compact and has served very well on two long trips.

I'm still reluctant to commit the a7RII ($3000 original cost) to underwater use, so was thinking of making a Meikon/a6300 the primary; and I could devote the $400 I would have spent on the Turtle to that system, giving me optical TTL in the bargain. Then too, the a6300 with 10-18 mm zoom would give me wide angle 15-27 mm equivalent; whereas, I'm stuck with 24 mm on the a7RII.

I saw some gorgeous large prints in Cozumel taken with an a6300, which may obviate the need for a large sensor with high pixel count. But then, the a7RII will continue to sit in a drawer.

I don't know how long the RX100 IV internal flash takes to cycle, but A6300 is not particularly fast in that regard - you won't get anything like 3.16fps you got with A7RII and wired sync, that's for sure. It also has an annoying quirk of slowing down to something like once in three seconds after firing off a series at maximum rate, and staying like that until the camera is turned off and then back on, however briefly.

If you're worried about taking an expensive camera underwater in a housing without a vacuum test system, you could probably sell your A7R II body and buy an A7R III body (about $1k difference), then add Meikon's new A7R III housing ($600), vacuum test system ($150) and 8" dome ($288). Assuming you already have a 16-35mm lens, this is in the same ballpark price as an A6300 + 10-18mm setup (that 10-18mm lens is expensive!) and will give you the best IQ that Sony has to offer while the vacuum test system adds a safety factor.

Very interesting. Thank you.

But has anyone actually dived with it?

But has anyone actually dived with it?

I received the product: SeaFrogs submarine strobe.

To start, I want to say that I am an expert in underwater photography. I have written numerous articles in the press and on French specialized websites and in particular on underwater strobes. I know particularly well the Inon strobes which this product is very similar.

The product is not at all according to its description.

The three main buttons have no function.

The main button turns on the strobe but does not allow to switch to different modes: TTL, manual, full.

The power adjustment knob has no effect in manual nor in TTL mode.

The mode button gives no function: it should cancel the pre-flashes in manual mode.

The flash fires well, but always with the same power without anything can be set.

To summarize, all functions are fake.

I received the product: SeaFrogs submarine strobe.

 

To start, I want to say that I am an expert in underwater photography. I have written numerous articles in the press and on French specialized websites and in particular on underwater strobes. I know particularly well the Inon strobes which this product is very similar.

 

The product is not at all according to its description.

 

The three main buttons have no function.

 

The main button turns on the strobe but does not allow to switch to different modes: TTL, manual, full.

i

The power adjustment knob has no effect in manual nor in TTL mode.

 

The mode button gives no function: it should cancel the pre-flashes in manual mode.

 

The flash fires well, but always with the same power without anything can be set.

 

To summarize, all functions are fake.

I'm on a Red Sea liveaboard right now, shooting a Sony A6300 with a pair of ST-100 Pros. I can't speak for manual mode, as diving with eight other people, I don't have much time to play with the settings, and this is my first time using strobes rather that LED lights, but its TTL cancellation circuit definitely works. It is horribly mislabeled as a 'memory recall' function, but with the right-side magnetic switch depressed, I see the characteristic double-flash of the TTL function executed, while with it pushed in and locked, there is only a single flash - which, with the Sony cameras having hard-coded TTL on the built-in flash, results in mis-sync, as it should.

Okay, so now that I'm back, and on a decent connection, I can summarize my experience, good and bad, from a dozen dives with a pair of ST-100s.

The good part is that they work, after a fashion, and that they're comparably inexpensive, though at $460 for the pair, still not exactly throwaway money. For my first run at using strobes, rather than natural light or constant LED beams, I got some photos that I'm reasonably happy with, for instance:

The bad parts are, unfortunately, quite numerous.

1. The initial pair of strobes that I received died after a few test fires on land - one stopped charging (the ready light stayed red), while the other had a green light, and the pilot LED would turn off upon triggering, but the strobe wouldn't fire. After an exchange of messages with the Aliexpress seller (Cameraman's Store), they instructed me to ship the faulty strobes back to Meikon in Hong Kong (cost me about $30) and sent me a replacement pair via EMS, with the shipping taking about a week in each direction.
2. While on land, both strobes appeared to fire, on the first dive I ended up with a bunch of images lit only from the right - the left strobe either wasn't firing at all, or out of sync with the camera. After fiddling with knobs and buttons, I somehow got both of them to work in TTL mode - facing the camera and pulling the trigger, I could see the double flash of TTL from either strobe (was testing them one at a time), but for whatever reason, the left strobe was still firing a single flash while on land - and sometimes this single flash would sync with the shutter, and sometimes it wouldn't.
3. I'm not sure that the TTL compensation works - I was getting some overexposed shots, and I tried to dial it down to -1EV, and it may have helped, but I couldn't do a controlled environment test, so it may also have been me changing the composition or the camera metering settings.
4. The manual mode does not work. Whatever I did, at least with the right strobe, I was getting a double flash of TTL. Pushing in the right-side magnetic switch, releasing which helped to activate TTL on the left strobe, did not deactivate TTL on the right strobe.
5. The YS-mount attachment bolts have large, easy to use handles to turn them - unfortunately, this causes one side to bump into the tray handle when I tuck the strobes in for a CFWA shot, or when I mounted them together with my video lights on triple clamps for night dives. I only had a leatherman with a bit set with me, so I couldn't get at the hex head screws holding the mount adapter, but I think with a longer allen wrench I can flip it around so that both bolts face outwards.
6. Both mode knobs, regardless of their utility or lack thereof, have tiny black arrows indicating where they're pointing. My eyesight is perfectly adequate, but at depth, these indicators are almost impossible to see without pulling the strobe right under the mask. I suppose a dab of white paint will help with that.
7. This may be a case of excessive expectations, but I kind of expected to have more power. Trying to light up a fan coral a couple of meters across, at around 20m depth, there just wasn't enough output to kill the natural sunlight - I had to fix the white balance in post and ended up with purple water, to wit:
   
   
   Yes, I know that the water color can be fixed too, and the shot isn't framed right, and I should've shot at closer range using 10mm focal length rather than 13mm (there was some current and I was afraid of getting too close) but that's not the point. To be sure, it may be a limitation of my camera - I saw a post today, by Pavel Kolpakov, claiming that built-in camera flashes tend to have a maximum burn time of about 1ms, while powerful UW flashes pulse for as long as 4ms, so triggering with the built-in flash may be incapable of extracting the full output of the flash in TTL mode. BM davec13o2 tested it with wired sync, and I understand that for him, the manual mode worked, including the variable power, but I don't have a wired sync bulkhead option on my housing, and I'm kind of reluctant to spend $500+ on a TRT Electronics LED trigger, which might not work with ST-100 to begin with.

Bottom line, while I'm not a particularly angry customer, I'm not a satisfied one either. I expected the same value deal from Meikon strobes that I got from my Meikon housings, and I did not get one. I will be having words with the seller again, but I don't expect much to come of it. I imagine I will use these strobes for a few more trips, then relegate them to backup status when I convince myself to part with the cash for a pair of Z-330s or YS-D2Js. In hindsight, I likely would've been better off paying a couple hundred dollars more for a pair of used YS-D1s or Z-240s.

 

..., but its TTL cancellation circuit definitely works. It is horribly mislabeled as a 'memory recall' function, but with the right-side magnetic switch depressed, I see the characteristic double-flash of the TTL function executed, while with it pushed in and locked, there is only a single flash - which, with the Sony cameras having hard-coded TTL on the built-in flash, results in mis-sync, as it should.

Hello Barmaglot.

I do not see this behavior on three differents SeaFrogs strobes. My test on Youtube in a few hours.

You're right, I'm not sure what it was, but one of my strobes was always firing in TTL, regardless of anything, while the other was sometimes doing a single flash instead of double, resulting in a lopsided exposure, and the right magnetic switch sometimes had an effect on it, and sometimes not - and it seemed different between on land and at depth, and sometimes turning it off and back on fixed it. Weird, although once I recognized the issue, I was able to deal with it. Regardless, davec13o2 has tested his sample with an oscilloscope and results are conclusive - when triggering off fiber optics, it always follows the trigger, and the right knob (EV adjustment) has no effect whatsoever. What does have an effect is flash compensation setting on the camera - I tested it with an A6300, while davec13o2 tested with an RX100 IV, and we got similar results. On the other hand, when using wired triggering, manual mode power adjustment does work - see his post here: https://www.dpreview.com/forums/post/61659150- and this also confirms my suspicions that my on-camera flash can't drive the strobe to its full power output. If level 8 pulse takes 1ms, then level 32 pulse should take 4ms, and if the on-camera flash is limited to 1ms pulse duration, then it can't drive the strobe to more than quarter power.

I'm considering getting an s-TURTLE trigger at some point - it still won't give me manual mode, but at least it should unlock the full power range of these strobes.

It's done the video is online :

https://youtu.be/mrlFmtkTGbM

davec13o2 has tested his sample with an oscilloscope and results are conclusive - when triggering off fiber optics, it always follows the trigger, and the right knob (EV adjustment) has no effect whatsoever.

The, I agree.

What does have an effect is flash compensation setting on the camera -

I also say it in conclusion of my Youtube video.