What are the settings for your photos? Shutter speed; aperture; strobe settings; ISO setting(s); RAW or jpeg; processing program?
My rule of (all) thumbs settings: ISO about 200; ƒ stop, one or two back from the smallest aperture; shutter speed set to adjust for desired overall background hue; strobes adjusted for exposure of subject; images saved in RAW. This is the gospel according to Cathy Church.
This is for a fiber optic triggered strobe system. I have a new TTL strobe, so next season will be devoted to figuring this out all over again.
With the camera info somebody may be able to help resolve the things you consider errors. Though for erroneous images they are quite good.
Generally, for shots with my Nikon 60mm lens I set ISO to 320, f/8 and 1/160 sec, then make adjustments from there depending on what I saw on the historgram.
Generally, for shots with my Tokina 10-17mm lens I set ISO to 320, f/4.5 and 1/200 sec, then make adjustments from there depending on what I saw on the historgram, and the tone of the background.
I need bifocals in my dive mask to even see the camera's screen, so I was really using the histograms to make my exposure decisions. I have been burned in the past by judging exposure based on what I saw on the camera's playback screen.
If I'm using the strobe, it's in TTL mode. However, in the caves I started shooting at ISO 400, f/3.5 and 1/80 sec., but the images were so dark that I ended up shooting at ISO 600 and strobes on FULL in order to get a decent shutter speed (>1/60 sec) to prevent motion blur. But I was at f/3.5 as a result.
Everything is in RAW, with some post-processing in Photoshop CS4, primarily color correction and spot removal. And maybe a bit of cropping.
The whole setup is new to me, including the lenses, so I'm still trying to sort out how to get a good depth of field with my macro shots. I can't shoot at f/22 and 1/30 sec. now can I? The hermit crab shot was nice, but it's out of focus.
I was also having trouble getting my strobes positioned correctly. I kept getting flat, shadowless photos that lacked depth. It is an art, figuring out how to get the best effect of shades and shadows.
Here's an example. This guy let me get right into his face. I shot a bunch of shots with strobes to either side of the port, but the light was so flat. I moved the strobes around a bit and came up with this, the best shot in the series. But I'm still not happy with the light and shadows.