How far away are "really good" tiny cameras for still/video?

Scott G wrote:

You do have a point.
At the moment I have a really small but very powerful video light on a tiny tray that has been "good enough" for the cold-water, somewhat murky diving I do (with the old GoPro). To really freeze action for quality photos I'd have to add one strobe at the very least and then, as you reminded me, the whole setup really does get bigger.
But lights and arms are fairly robust and foldable. the camera housing is a big lump (at least 6X size of GoPro housing, with multiple, large O-rings etc) and I'm not sure how robust. Certainly any dome port and O-rings need serious care and attention.
Ha ha - there's no silver bullet out there yet...

I dive with a Sony A6300 in a fairly substantial SeaFrogs polycarbonate housing with a tray and a pair of strobes, and while this is highly subjective, I feel that most of the bulk - even accounting for an 8" dome on the housing - comes from the arms and strobes. Even folded up, the four 20cm arms with strobes hanging off them are quite unwieldy and add substantial underwater drag.

As for the 'really small but very powerful' video lights, they are several orders of magnitude less powerful that strobes. Comparative testing indicates that it will take about a million lumens of constant output to match the prompt brightness of a Sea & Sea YS-D2. Consider this: a typical strobe running off 4xAA batteries is rated to about 300 full-power flashes, give or take a bit. Each flash is about 3ms long. This means that if you were to run it constantly (physically impossible; it would literally explode if you were to try something crazy like that, but this is just a thought experiment) , the batteries capable of running a regular light for a couple hours would be drained in less than a second.

Regarding the advances in smartphone photography, keep two things in mind. One: phones have a much, much lower starting point - the chasm between the capabilities of phones and digital cameras of early 2000s has certainly shrunk, it's not going away anytime soon - you can't cheat basic physics, and the actual resolution of the camera's sensor is limited by factors such as the airy disk. Two: the huge advances in phone camera image quality have largely come from computational photography - increasingly sophisticated software in the phones interpreting and processing the camera output. This is achieved by huge multinational companies pouring literally billions of dollars into R&D on this - but underwater, the camera output is highly, let's say peculiar, and all that R&D has little relevance. There is the 'Dive+' app that processes underwater images on smartphones, but don't expect miracles.

Finally, keep in mind that no currently available camera sensor is capable of syncing with strobes without the aid of a mechanical shutter. This isn't physically impossible, but currently available electronics - even in extremely expensive cameras such as Sony A9 - are far too slow to read out the sensor output within the duration of a flash pulse. This is something that will probably get solved in the future, but how long it's going to take is basically anybody's guess at the moment. Right now, no smartphone or action camera on the market can sync with xenon strobes, and LED flashes are far too weak to be useful underwater. There were a few smartphones with xenon flashes and mechanical shutters made in the past, but none of them are currently in production.