The risk is overall not worth it, and in any case, the image is an ugly green, and welder’s glass doesn’t always have a good optical quality which would result in a less-than-sharp image of the Sun anyway. Only certain types of welder’s glass absorb enough light to be used safely for solar viewing – others let in too many harmful UV rays (or just too much light altogether), and some can even provide a too-dim image. Hold the filter/glasses up to the Sun or a bright light and look at the ground to be sure there are no pinholes that can compromise your safety. Unless your solar filter is a solid glass design, it probably uses a thin, Mylar-like safety film. All that was salvageable were the mirrors and a few other parts, and there was a large scorched patch of ground next to where the scope was. I recall a story of a man whose shroud slipped off his 25” (yes, 25”) Dobsonian during a gust of wind and the scope proceeded to ignite both its wooden upper tube assembly as well as the area around it. Going blind is bad enough, but a large Dob could easily start a fire on a sunny, dry day if sunlight strikes the primary mirror, igniting its own wooden components or nearby grass. Don’t use a large Dobsonian telescope for solar observingĪ big Dob not only is pointless for solar observing (daytime seeing always limits a scope above 6-8 inches) it’s also dangerous.Even with a light shroud, all it takes is a slight breeze to potentially let sunlight in to hit the primary or secondary mirror and blind you. This seems obvious, but with the advent of low-cost collapsible-tube reflectors, people seem to be doing solar observing with them more and more. Don’t use truss/collapsible tube telescopes for solar observing.Always make sure your filter is securely attached to your telescopeĮven if sunlight is not directly shining into the objective lens or mirror of your telescope, it can easily bounce off the tube walls and find its way to the eyepiece. I have met folks who have had permanent eye damage from using these devices or ones who walked away from their telescope only to come back and find the filter cracked! Being so close to the focal plane of the telescope they are subjected to an intense, nearly focused pinpoint of light and heat which can crack them (and in turn let the unfiltered sun into your eyes) in under a second. Many older (particularly Japanese-made) refracting and reflecting telescopes come with these, as do (sadly) some cheap department-store telescopes.
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