An Optics Demonstration in the Sauna

Earlier this evening I took my first sauna of the season. The temperature reached 149 degrees Fahrenheit an I don’t wear my glasses under such circumstances. The sauna does have a timer in the control panel and I knew the length of the playlist on my iPhone playing on my Bose on the wooden bench outside the glass doors (better than the built-in speakers). But now and then I wanted to check the remaining time on the control panel, less than six feet away. There’s no way I could do that with my naked eyes. So what I did was create a pinhole effect with my right index finger curled to its maximum almost and then resting against the palm of my hand and my outstretched thumb. That way, I could see perfectly clearly what the temperature was, and how much time was remaining on the timer.

This pinhole effect, as it is called, can overcome nearsightedness and farsightedness, even to fairly extreme degrees, because the small hole only allows the straight light beams to go through, not the ones that come from further away from the center. Early cameras did not have a lens. They just had a pinhole, for example.

I love optics and ophthalmology and briefly considered becoming an eye doctor myself, but I worried that an extremely nearsighted eye doctor might have trouble doing his job, and I was also worried that I might be at risk for retinal detachment because of my nearsightedness so I became a family doctor interested in eye diseases. I’ve written about that a few times before.

Altered Vision

Low Tech Medicine

A Bad Case of Congestion

Not On Call

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