How far off-axis does my strobe NEED to be?

[tursiops]

Most people taking pictures u/w want either a good picture, or are happy with a crappy picture. Both solutions exist, but not in the same package.

 

[sea_ledford]

Just as a thought exercise, I suppose I'd define what I'm looking for as

• an attachable external strobe,
• preferably supporting TTL,
• on a foldable arrangement so it could be used folded or unfolded,
• and the folded arrangement fits a drysuit pocket.

(I'm either looking for something the market doesn't desire; wouldn't be the first time -- or there's an unmet need here and quite a few smart people missing it.)

You are all good until the last requirement. Unless you've got REALLY big drysuit pockets!
You are asking for an F-150 that is the size of a mini. It's not the market that is the problem, it's physics.

What might work better for you would be a small camera system and a video light that you just use as a hand held dive light. Get a camera with great low light capabilities, and a Light and Motion Sola video light and you would be good to go.

 

[Chris Ross]

It all depends on what quality you'd like to accept - you can dive with a camera with no lights, doing a custom white balance down to about 10m and get pretty decent results and that you can put in your pocket. If you want lighting you need arms and the size of the rig automatically multiplies. You can go with the short arm solutions but they are limited - you need to get the strobe away from the lens by a decent amount or you'll get a hotspot from close in particles.

It also depends on what shooting arrangements you are using and where - a fisheye with CFWA shots where you are right on top of your subjects in clean tropical waters you can attach your strobes directly to your tray handles with a long clamp and it'll work. There is a reason people use the arrangement of two arms/three clamps for each strobe and that is because it works. Convenience and UW photography generally don't go together.

I have a friend who bought the ikelite DS-51 and that arm arrangement to use with their compact and frankly it was terrible very clunky to use - to the point they don't take their camera with them any longer. It's night and day to my setup using two INON strobes on the standard two arm/three clamp arrangement. With my setup you just move the strobe where you want it and it stays there.