I looked around and perhaps missed it but does anyone shoot manual camera and manual strobes but use Auto ISO?

Same, manual camera settings, Auto ISO but with sTTL?

I would think the former would not work, since the ISO will be set based on some kind metering, which will probably happen before the strobes fire?

I think I used to do the latter fairly often when I had an sTTL setup. I can't claim the results were great, but there were many reasons for that (including me).

Edited July 4Jul 4 by d2b

36 minutes ago, d2b said:

would not work, since the ISO will be set based on some kind metering, which will probably happen before the strobes fire?

I have found this to be correct.

The only time I have found auto ISO super useful is if I’m on the surface and want to grab a quick frame of the approaching boat, etc. and don’t have time to readjust the manual settings for the bright ambient light.

The metering would be the same as would occur in Tv or Av? But those would be fixed so it is the ISO that is allowed to float if Auto ISO selected? Really, I have no idea, thus asking you folks with more camera knowledge?

Sure the metering is the same, but Tv and Av will have the same problem with stobes in manual mode: the camera will assume things are very dark, and once the strobes fire things will (most likely) be overexposed.

Your problem is the strobes don't know what the camera is doing, so if you have manual strobes the exposure is only correct at one ISO, but if the camera changes that the strobes still fire the same burst if they are on manual. Seems like a recipe for frustration.

sTTL may have a chance to work as the camera will vary the flash output to adjust exposure. The issue is going to be how well the camera interprets the UW scene and what it tries to do with it, so you are likely to need flash exposure compensation as well which may or may not be quick to get to and adjust. Put it another way if sTTL works for you with fixed ISO it should also work with variable ISO, within a small range. If the ISO moves too much you might run into problems and need to move SS or aperture to deal with it.

The other issue is going to be that at least for daylight reef photos you are often pushing up against your sync limit and it won't take much to reach it so the the range the ISO can move is probably boxed right in. So might as well use fixed ISO. For macro with black or dark backgrounds the auto ISO is going to try to make that neutral grey so I can't see auto ISO working that well, again depending on how well your camera's TTL reads a scene like that.

6 hours ago, Nemrod said:

I looked around and perhaps missed it but does anyone shoot manual camera and manual strobes but use Auto ISO?

Same, manual camera settings, Auto ISO but with sTTL?

Only accidentally. Quickly remedied.

Hi @Nemrod

I’ve had course guests get in touch with me with their compact cameras using this method but the exposures aren’t always correct, or the subject is blurred.

I’d always recommend choosing the correct ISO based on your subject choice to get the best results.

I've tried it with hard wired older Ikelite TTL and current sTTL (Inon) and a few other sTTL / TTL systems.

Unless in a bright almost surface condition like Chip and Chris refer to better to pick a fixed ISO then sTTL / TTL will do it's thing better. Of course this is based on f-stop, strobe to subject distance, individual subject reflectivity, etc.

It's also easier to change ISO on modern mirrorless cameras up or down a bit then continually changing shutter speed / f-stops once you've set up for depth of field, etc.

DH

Photo of me in Alexander Springs April, 2025 taken by my friend and PRO UW photographer Paul Rudin :)

Edited July 5Jul 5 by dhaas