Light paint + Long Exposure Question

[A/Ox4]

I am planning on taking a star trail photo tomorrow, and I was wondering, if I have my friend step in frame and paint her with a light, will she be ghosted in the final image if she isn't there the whole time, or will she appear normal?

 

[Buckster]

If there's any light behind her at all, including stars, she'll be ghosted.

 

[A/Ox4]

That's what I thought.
Photoshop might be the answer

 

[jsecordphoto]

The only good way I've found to have a person in a star trails photo is layer mask them in. Take your star trails photo(s), and then take a frame with a person in the scene, then combine them in post.