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Message: <blockquote data-quote="jring" data-source="post: 3598106" data-attributes="member: 133897">Hi,but please note that the author is writing about naked eye observing and also states that while the quite fast (few tenths of a second) heating effect is negligible then, it might be quite different when using optics due to the fact that when a larger area is heated by a magnified image, there is less heat transport due to temperature gradient.The photochemical damage by blue light seems indeed to be in the one second to a few seconds range (depending on latitude) for maximum safe observation time, so an accidental glimpse of the sun will probably not be disastrous due to that effect. As Binastro wrote, there is ample evidence of permanently damaged eyes due to insufficient protection while observing the sun with astronomical telescopes - at least one case instantaneous. Also things get quite hot with Herschel wedges or the terrible eyepiece sun filters which crack due to heat and should be destroyed on sight.The question remains if this heat induced damage is also happening with binoculars and at what time. If you have access to science journals, it might be interesting to have a look at the two articles on heat damage cited - hopefully more information is found in there:Vos, J. J. 1962 A theory of retinal burn. Bull. Math. Biophys. 24, 115±128.White,T.J., Mainster,M.S., Wilson,P.W. and Tips,J.H. 1971  Chorio-retinal temperature increase from solar observation. Bull. Math. Biophys. 33, 1±17.Joachim</blockquote>

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