Thanks to each of you; your feedback is very much appreciated.
John, I understand what you're saying. I've gone through a lot of the same thoughts myself. There are many ways this image can be processed, and I've tried quite a few of them since I first took this shot several years ago. And there are a number of versions that I like. In fact, in my latest revisit to this image, I produced a few new ones that I thought had merit. My wife actually favored a different one than I decided to post here. In the end I think it's a matter of taste, and it's possible that the next time I come back to this, mine will change. But for what it's worth (probably not much), here are some of the thoughts that went into producing this one.
Though the wheel irrigator is the object in focus, I don't actually consider it to be the main subject of the picture. It's purpose is to provide context that the location is a farm, and some strong graphic elements for the composition. The real subject is the interplay of the first rays of sun through the fog and onto the irrigator, which struck me as quite extraordinary. (If there had been no fog, I don't think I would have taken this photo.) So though the irrigator obviously plays a critical role, I didn't want it to be overly dominant. Lightening the cog shifts too much visual attention there, I decided. But in the end, the main factor is that I just liked this particular arrangement of light and dark tones; it resonated with me, and so carried the day.
