At What Distance Can the Human Eye Detect a Candle Flame?

June 2, 2024 5:30 AM

"Nevertheless, we have shown that a candle flame at roughly 2.6 km would have an apparent brightness comparable to a 6th magnitude star. Could the keenest human eyes on the planet see a candle flame at 10 miles? We have provided strong evidence that the answer is No, for it would be as faint as a star of apparent magnitude 10, and that would require a pair of 7 X 50 binoculars mounted on a tripod, even for experienced observers with good night vision."

I'm sharing this article after encountering it this morning while trying to figure out how far away a character in a story could see a flame. If this has ever been published outside of arXiv, I couldn't find it on a quick search.

CITATION

Krisciunas, Kevin, and Don Carona. "At what distance can the human eye detect a candle flame?." arXiv preprint arXiv:1507.06270 (2015).

posted by cupcakeninja (9 comments total)

(wiki) fresnel though
posted by HearHere at 5:35 AM on June 2

I love it when scientists just unload a pile of pedantry to correct a minor point that no one really cares about (I'm not being sarcastic - this is some next-level pedantry and worthy of applause).
posted by JustSayNoDawg at 5:45 AM on June 2 [6 favorites]

it is debunking false advertising, to be fair
posted by HearHere at 5:47 AM on June 2

This recent episode of Veritasium exploring different types of night vision technology might be of interest.
posted by gwint at 5:51 AM on June 2 [3 favorites]

i also appreciated learning A shift from phototopic to scotopic vision makes a significant difference in the results, thanks!
posted by HearHere at 6:29 AM on June 2 [1 favorite]

One of my favorite facts is that until the year 1600 or so there were only five thousand stars. It's a lot but in theory you could enumerate them all (and plenty of early scientists tried).
posted by Nelson at 7:55 AM on June 2 [2 favorites]

One of my favorite facts is that until the year 1600 or so there were only five thousand stars. It's a lot but in theory you could enumerate them all (and plenty of early scientists tried).

I’m reminded of Calvin’s (not that one!) dad’s explanation that the world used to be in black and white prior to the 1930’s. I know that’s not how you meant it, but any excuse to mention a classic strip is a good one. The paper was quite the tour de force (however you spell that…).

Reddit link to a copy of the strip in question.
posted by Gilgamesh's Chauffeur at 8:15 AM on June 2 [2 favorites]

It is better to move a candle closer than to curse your visual acuity.
posted by fairmettle at 9:45 AM on June 2 [4 favorites]

Well you can't hold a candle to that.
posted by y2karl at 5:31 PM on June 2