This column has already written about the need to avoid white light while you are observing so that you can preserve your ability to view faint objects in the sky.
Once lost, this so-called dark adaption can take several minutes to return as your shrunken pupils expand fully once more to soak in those photons that have spent such a long time beaming their way across the universe to your eyeball.
So what to do when you’re out there at the telescope and you suddenly realise you’ve left something vital indoors such as an eyepiece, star chart or cup of coffee? If you’ve family in there living a normal life, you can’t just turn off all the lights. Neither is it safe to walk around with your eyes closed.
Thanks therefore to Brian Livesey, from Lancashire, for reminding the SPA Forum of a handy tip suggested by J B Sidgwick in his classic guide Observational Astronomy For Amateurs. Buy a pair of swimming goggles from a sports shop and replace or cover the glass with red cellophane. That should help you to see your way, save your sight . . . and probably give the family a good laugh into the bargain.