To be honest, this is one of those cases where I don’t think it’s possible to give a single brand or model the honor of being named “the” best astronomical red flashlight. This is largely going to be a matter of personal preference. But, that said, we can certainly discuss the features to look for in a red flashlight, as well as some particular models that may or may not meet your needs.
Why Do You Need One?
Without going into the details (because that’s something for a whole different article) red lights are important for astronomy because they are less likely to mess with the dark-adaption of our eyes.
When we are in the dark, the pupils in our eyes dilate and the photosensitive pigments in the cells of our retinas build up more, making our eyes more sensitive and able to see more and more with less and less light. The longer we stay in the dark, the better adapted our eyes get. Unfortunately, even a little stray light can completely wipe out that adaptation, putting us back to the beginning. If you turn on your phone while sky watching, you’re doing just that.
But our ...