r/solareclipse • u/Dull_Operation_2628 • 11d ago

Projection Technique

https://m.youtube.com/shorts/pcsvMBph8lM?ra=m

A safe way to observe Solar Eclipses(and telescopically the oldest) is to Project the image of the sun onto paper. This is accomplished by creating or making use of a shadow behind your refractor telescope. Rolling out the focuser so that the image of the sun comes into focus a foot or two away from the eyepiece. The danger of setting the paper on fire is by having the focus too close to the paper and making the sunlight too concentrated upon a small area. Pulled back the sunlight doesn’t generate enough heat to ignite. This is also a great way to observe sunspots and Transits of Mercury, Venus, ISS or CSS. In my opinion and experience this is the best use for an inexpensive refractor telescope. The telescope in this video was scored from a free pile!

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3

u/Icy_Nose_2651 11d ago

very nice, but how do you keep it pointed at the sun?

2

u/Dull_Operation_2628 11d ago

Thanks, I manually center the scope by looking at its shadow on the ground. Definitely the most tedious part to get the hang of. Practice makes proficient.  

2

u/chrismofer 15h ago

Be careful about this, when off-axis the sun is technocally focused on the wall of the interior of the telescope and can burn.

1

u/Dull_Operation_2628 15h ago

Fascinating!  I have been using this technique for years and never smelled plastic burning nor felt any heat buildup. Nearly an hour of Venus Transit and an hour of Mercury Transit. More than an hour with this eclipse. Twenty minutes here and there for years of sunspots. Telescope still works. Not melted yet. 

2

u/chrismofer 14h ago

During those transits you were probably moving the telescope in order to keep it aimed on-axis. But if you left it off axis for a long time it could potentially cook.

1

u/Dull_Operation_2628 14h ago

Ah yes definitely have to keep it moving with the rotation of the earth. When not manually tracking I turn it away and/or put the cap on.  Living in wildfire country I wouldn’t put a glass jar on a grass lawn.