Roger
Excellent test. The validity of additional lighting outdoors for augmenting the limited dynamic range of the camera is well demonstrated by your shot of the black bird with the really ugly head. (A condor? Sorry, I have no idea, city boy that I am!) The definition of the feathers make the shot.
On the locomotives, I suggest a 1:2 or 1:4 ratio in stead of a 1:1. I think it will look more natural. It would open up the shadows enough so you can see more details but avoid flattening the image contrast. Without the contrast, all those pipes become confusing. Also you need to avoid creating an additional, distracting shadow.
Thanks for posting!
Dennis
"Coal Smoke Is Good For You!"
Some of my rail pictures here:
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www.railpictures.net]