Controlling exterior lighting in various environments

I am struggling to control light/shadow and reflections when rendering with environment backgrounds.
I am rendering a ship on the sea (watersurface is modeled), and if I apply a colored or image background the light changes significantly on my model without me having found out how to control it. I have played around with advanced background settings, without getting any understanding of how/why light changes. This is to me the least intuitive content of Flamingo nXt…
I have walked through all tutorials I have found on Flamingo nXt environment, but none of them are covering/explaining external light (sun) behavior with background environments.
Does anyone have a tip for a book/manual/tutorial that can help me understand and control this?
Or is this a weakness in Flamingo nXt that is best “solved” by moving to Brazil or V-ray?

This might help… http://nxt.flamingo3d.com/page/image-adjustment

nXt will “tone-map” the image to prevent an overly bright or dark render. You can adjust the settings explained in the link above to taste but there is no way to stop nXt from tone-mapping the result… to my knowledge. You can try using Lock Exposure and re-rendering but depending on what you’re trying to overcome, this may not help. Post a simple scene and some renders of what you’re trying to change if you need more help.

Brazil and Vray are excellent renderers but the learning curve will be longer than nXt.