Digital Pro Flash + Shutter Speed

[xyrandomyx]

I have a DC 1400 with the Digital Pro Flash. I've been having trouble with overexposed/ washed out images, so I decided to experiment a little with the flash and exposure settings on dry land.


I turned the external flash's brightness setting down as far as it would go. I set the Scene Mode to ExtFlashMNL. I set ISO to 100, aperture to F7.9 and shutter speed to 1/60. I took a test shot from about 1 metre.


I then changed the shutter speed to 1/125. I took another test shot -- it came out brighter/ more exposed. I set the shutter speed up further to 1/250 -- the shot was even brighter.


How does this work? My understanding (I'm a complete beginner, so I could be entirely mistaken) is that the shutter speed only affects ambient light, not the flash. So I was expecting to either see no difference or a less exposed shot (due to ambient light).

 

[xyrandomyx]

No replies here, so I started another thread: http://www.scubaboard.com/forums/underwater-photography/443460-external-flash-shutter-speed.html. The replies there and some more fiddling have led to two new questions:

- In ExtFlashMNL Scene Mode, is everything in manual mode or is there something else I'd need to switch off to get to a full manual mode?
- Does the power setting on the external flash adjust the power entirely, or does it just fine-tune automatic power adjustments?

 

[SeaLife Cameras]

Thanks for inquiry. We are in the process of researching the issue and will reply ASAP.

 

[xyrandomyx]

Thanks for inquiry. We are in the process of researching the issue and will reply ASAP.

Thank you very much. I also posted a similar question in the general UW photography forum:

www.scubaboard.com/forums/underwater-photography/443460-external-flash-shutter-speed.html

I mentioned in that thread that after some more experimentation (and ruling out a few possibilities), it seemed to me as if the camera is automatically setting the ISO (even though it's been manually set 100). I can't be 100% certain, but the increase in digital noise as the shutter speed is increased makes it seem quite likely to me. Thought I'd just mention that in case it helps.