I try to take a long exposure of the stars, and then explain how I figured out the settings for that shot compensating for reciprocity failure.
A short video where I try to clarify the process of making long exposures with film. Remember that I wrote a whole book about this topic that you can download for free. I also have a few articles about Long Exposure Photography on this blog. Please don't hesitate to drop me a line if you still have any questions.