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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
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