Klaus

We do need that Waterpixels-branded fishing vest in the online store, don’t we? 😉

Totally agreed. There is a need for packable, light and sufficiently powered strobes for those who travel with maybe a pair of hiking boots or things like that in addition to the UW photography gear. Sure, 4x AA won‘t recycle very fast, but the longest recycling time is for the strobe that had to stay at home 😉 And for everyone else there‘s other brands that offer long-life Lithium-powered light sabers. It‘s good if we can still choose which compromises we want to make. And as far as I can tell the new Inon does not even „need“ to be stronger since the Z330 is not available any more? So there may be some ambitious marketing claims, but even if it is a down-to-earth Z330 remake it will have its niche in the reef.

From what I know of HSS in dry-land you will always want the maximum output - or more still. Turning it down may be technically feasible (Marelux?) but rarely useful. Back to the original question - backscatter: Since we agree that HSSis essentially the same as using an LED torch, does anyone have comparative experience between strobe and LED-light for the white thingies?

Let‘s not get worked up on this too much - those who are fully satisfied with their strobe might not even read this thread. On the other hand, is it possible for a UW photographer to be fully satisfied with ANY strobe? There are some fundamental laws, and one of them says that energy can only be transformed but not created. And another one says (more or less) that all energy transformations are associated with losses. So current to light and heat as loss. Inon makes a clear statement in the instructions that you should not fire flashes at full power repeatedly. Sea&Sea did not, but the D2 earned a reputation. I guess that there may be some differences between the brands, but 4x vs. 8x AA is DOUBLE. They simply cannot be that ignorant at Retra. It would require the very first generation of „auto“ strobe circuits, which just dumped the rest of the charge after switching off the tube. This was before 1970 or so. Can we get back to the Ionon Z-XXX that at least some of us find interesting? Any pictures that we LIT by one or two of those?

That certainly works when you are using a snoot, but HSS? Seems unlikely. There‘s just no difference between 1 and 10x 0.1 if summed up. And if 0.1 is below the detection threshold each time due to absorption, then that is the same for the subject. Commonly, we refer to this as underexposed. The only chance would be to have the particles move - then the subject may get 10x 0.1 but the particles will only leave a trail of, say, 2x 0.1 on each pixel. Waterpixel, to be precise 🙂 But is it true that backscatter manifests itself as streaks of lower intensity when one uses video lights to illuminate a still?

Maybe it helps to look at this from a different angle. What the HSS pulses achieve is in essence to turn a strobe into a constant light source like an LED torch. (This is a simplification but bottom line that‘s it for still photography.) Any BS reduction due to particle movement should thus be observable using video lights as well. For macro that is indeed a valid option - and the longer the shutter speed, the more pronounced the effect should be, provided the subject stays rock-still. So, has anyone observed less backscatter when using video lights for macro shots compared with strobes? I honestly don‘t know, I‘ve never read anything along those lines.

I've always wondered when looking at the pictures of the AOI strobes and Backscatter's MF - strobes whether these are actually more or less the same "under the hood"? At least the front view of the reflector and the LED's looks suspiciously similar, so I assume that coverage will be more or less identical. Factor in that Bacscatter works together with AOI for other pruducts... Of course, the electronics may differ (and that will make a difference for output) and certainly the design of the stobe overall. But I've read on other occasions that wide-angle shots CAN be done with a pair of MF's. It was never recommended as an ideal solution, but as a setup that can work if need be. It seems to me that the MF-2 is a bit better for macro due to the design and accessories (snoot), so perhaps 2x MF-2 is a bit more universal than 2x AOI? Just a tought.

Great shot, envy or not. 😉 So, @bvanant does that housing have the Pen size port mount? I know I’m hijacking the OP’s topic here (apologies) but for completeness sake: Does the AOI OM1 housing allow continued use of Pen-ports when upgrading to an OM1?

I once read that the AOI polycarbonate housing for the OM-1 uses the ports from the former Pen-series housings (better to check this yourself). In that case, the adapters mentioned above by @Griffer should indeed allow you to continue using your PT-EP08 ports. Rumor has it that the Olympus Polycarbonate housings were made by what is now(or already back then) AOI, hence the adapters for the EM-1 housings should fit. Maybe some of the seasoned members can comment on this - I would like to know more about that myself, too.

Noise in underexposed areas of my pictures is not « colored » unless the white balance is (purposefully) off. So I don’t believe that thresholding plays a role here. I think the quantum yield is in fact lowest for the GREEN pixels in the Bayer array, but did not look up any reference for that. I vaguely remember that’s why the square array has a 1xB /1x R /2xG geometry, but frankly one should look this up again to be sure. But in the end, why bother? As long as we’re satisfied with our 50 shades of blue, does it matter how we achieved it?

Sorry, hit it too fast. Lambert-Beer’s law describes the remaining light as a function of extinction coefficient AND distance (in the lab, that is the thickness of the cuvette).

I am afraid you are describing the effect of distance rather than exposure time.

But for a reef scene it would be 0.03 or even less - 0.3 is 1:3 so still a close-up, right? Whatever, those who can shall try but I seriously doubt it’s worth the effort.

I think you need to factor in the optics in the calculation - 11 um on the sensor is more in the water, unless you are shooting 1:1 macro. I would assume that the need for HSS occurs more frequently at the fish portait-to-reefscape scale, so then the particles need to be more like 10x these speeds? If this really made a difference, the forum would be full of examples and our GAS would be over and done with already…

Yes, but they are dimmer in absolute terms. What counts, though, is the relative intensity when the backscatter is compared with the subject. HSS compensates the fact that at faster exposure speeds, the shutter curtains move as an open stripe from top to bottom and multiple strobes (as in stroboscopic) illuminate the sensor as the curtains travel down. Thus: The backscatter-causing particles and the subject will receive the same amount (relative to each other) of light in both cases - HSS and « normal » strobe. If the backscattering particles move in an HSS relevant way, i.e. extremely fast (we’re talking about shutter speed above 1/250 nowadays), then there is too much current and you should get out of the water asap. It should also blur the particles in a similar way for the standard strobe, if not more (full dump is longer than the stroboscopic action). And apart from solid structures, your subject will likely experience the same ripping current. It’s unlikely to be a great shot… I think there are more important reasons to use HSS than backscatter reduction, but in the end it’s user experience than counts - and I cannot provide that for underwater. But top-side I can attest that HSS is not the solution for when it snows 😞

As far as I understand it the warmer strobe colors are a benefit if you (or your camera) adjust WB globally. If you apply a mask during post processing and adjust the WB separately for foreground and water, then I can imagine that the strobe color is not so important any more. I have never tried this, though, because I find making these masks tedious. but above all, I am already super-happy if I get the balance of strobed foreground and background water right for once…

I‘m so jealous- Flores Island is sooo nice! We‘ve been there last summer but didn‘t have enough time to go scuba-diving (just a bit of snorkeling). Scuba is also not very easy to find, or do you know a dive center on the island?

Since you have mentioned traveling - the Canon is APS-C format and hence the lenses will be a larger than micro 4/3 (EM-10). This makes the entire setup a bit larger on the port side. For the EM10, AOI has a polycarbonate housing which is compact and probably of decent quality (the AOI is maybe easier to get from within Europe than the backscatter octo design). This will be easier to pack & travel - whether the EM10 is as capable a camera I don‘t know. I have a Nikon D-3300 APSC SLR and an Olympus EPL-5 MFT. Honestly, with images printed up to 80x60 cm (or 90 x 60) I don‘t see a difference in quality with top-side pictures. This is old gear and I only take the MFT under water, but my guess is that autofocus is more important to worry about than image quality. Perhaps you can test these on dry land by lending them from a shop for a day or two? Lighting with torches can work well for macro, that’s how I started as well. But strobes will probably bring out significantly better quality from the TG4- sensor. Maybe you should start simply with e.g. an MF2 strobe added to your TG4? The strobe will be useful with any camera afterwards.

… and some of those aboard might even smoke 😮 Ok, that’s a completely different story but it nonetheless exists. lithium batteries are not unsafe per se - we might never have seen as many NiMH powered devices in circulation as we do for Li-Ion now. But they are certainly more sensitive to how they are treated, and that‘s where the parallel with smoking may be appropriate. As long as the companies offer a choice - all the better.

I use an epl-5 with the little add-on strobe (in the Olympus housing), this connects through the accessory port and is likely very comparable to the EM-10 pop-up. This syncs at 1/250, but any strobe on the „real“ hot-shoe will only sync at 1/160. The manual also states that rc mode with the little guy only works down to 1/160. I once tried an old strobe from the analog days (risky, as some of those can damage the electronics) and that worked at ANY speed. Thus, the hot-shoe gets a simple electric signal (contact closed) whenever the camera takes a pic. This is of course in manual mode (for speed and f-stop). I found that I could even go 1/320 with this and did not see any shadowing by the shutter curtains. That may not be 100% reliable, though, and perhaps in 1 out of 20 shots there will be some shadowing? Long story short: It is possible that the AOI „manual only“ trigger might even work at shorter than 1/250 shutter speeds. The simpler the device is, the shorter one could go I suppose. However, I think that TTL is worth more than that extra short sync speed, so this is not intended as a recommendation. But perhaps someone here owns the manual only trigger from AOI and could share the experience?

Possibly the 1/250 can only be used with the built-in pop-up flash of that camera. This would make the statement „formally correct“ with 1/250 sync speed, but it is a bit misleading indeed.

Thanks for the info. The owner is Tomos (likely Tommi), he also served as the captain and guided the whole group on one of the dives. I do not remember his father’s name.

If you place the 90 mm in a flat port with 67 mm thread, you could widen the perspective (and depth of field) with something like an Inon UWL-H100 wetlens? Without the glass dome, that makes about an 0.6x for the focal length, so should get you somewhere in between the 30 and the 90. It won‘t better the IQ, but it’s not too bad either. I have a hard time distinguishing afterwards which of my images were shot with that wetlens on. There may be a more recent version by now. However, it will make the rig even more nose-heavy… Not sure whether these air lenses (giving 0.7x) are of good enough for your purpose. The opposite strategy has been mentioned before (30 mm and cropping). Sounds like less hassle to me + AI upscaling can do small wonders these days.

Crossing over to "Critter Identification" now. You mentioned corals - which I am surprised to hear about for Croatia (except the Gorgonians). I have this picture: But that is not a coral - right? It was taken quite shallow, like 8 or 10 m if I remember right. Would anyone know what kind of a critter this is?

Indeed, this was the Vranjak II and it is now run by the son of the former captain. If fact, dad joined us on the trip as an additional hand because of the weather (see below). We went during the second week of September and a 7mm semi-dry was more than sufficient, I ended up diving without gloves down to, ahem, 40 m or so. The weather has been more extreme recently, the sea is warmer, more humidity in the air - we all know the story. This is most noticeable at the end of summer. During our trip there was one day where we couldn‘t dive at all because it was too risky to take the boat out of the harbor. Instead, they ordered cabs that took us to a regional park for a bit of hiking on the cliffs of Dugi Otok. We had nice weather for that, but there were other places really close-by that were hit by a Tornado and had cars washed down the village streets. In essence, I guess the captain took the right decision, plus he did not leave us with a simple deck of cards and this was smart. However, I think the best season may therefore be August nowadays. It might be fun to organize a tour with that boat, but it was really not conceived with photography in mind. I can‘t compare it with anything else, but some other guests said that the liveaboards are slightly more spacious elsewhere. Gut feeling: This is OK for anything ranging from a GoPro, housed smartphone etc. up to a small MFT rig (think Backscatter „Octo“ class). But the full-frame behemoths I have seen on other occasions might be challenging, especially if there‘s more than one aboard.