Dandelion

I thought I was going to miss blipping a dandelion clock this year, it keeps raining and they get spoilt. Then, because I really enjoyed the one I did last year I didn't think I wanted to do one again.

However a change of camera, a change of macro equipment and dedication to using a tripod made me have a go. This time no jiggery-pokery with filters in PS, just a stack of 6 photos.

Don't ask me where the rainbow effect came from, it just appeared when the images merged. Any ideas?

EDIT: The description of the process is given in the comments so that I can get back and edit it if I learn something more after this edit gets frozen!