I don't know Nebulosity but in the Envisage software try adjusting the histogram sliders so the top one (black point) is closer to the left and the bottom slider (white point) is closer to the right. Try it in small increments until it starts to look ok. What may be happening is as I mentioned above the software may be trying to automatically adjust the image to make the object visible (in its own mind) but you may not have enough signal for it to work properly and all you end up with is fuzz. Not being their I can only guess that this is the problem. Give it a go and see how you go.
Also have you tried using it during the daylight on a distant tree or something?
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