Astronomy Stack Exchange is a question and answer site for astronomers and astrophysicists. It only takes a minute to sign up.
Sign up to join this community
August 21 is going to see a total eclipse across most of the US, and I'm planning a trip to what I hope is an ideal viewing location.
What are good ways to safely view the eclipse?
I don't want to make a big trip out of it, only to be looking into a poor quality pin-hole shoebox, or $2 mirrored cardboard glasses. How can get I get a good, detailed clear view of it while staying safe? What about ways to photograph it effectively?
Projection is a safe way to view the partial phase of the eclipse.
A pinhole produces a small image of the sun, but doesn't require any special equipment. A larger image can be obtained by projecting through a telescope:
Point the scope at the sun, but never look down a scope that is pointing anywhere near the sun, neither look along the tube. Use its shadow to line it up with the sun. Hold a white card half a metre or so behind the eyepiece, and focus the telescope to make a sharp image of the sun. You will want to provide some shade for the image.
Image from Bakersfield College
This works well with binoculars, you need some way to mount, or prop up the binoculars, and you will need to cover up one of the lenses (or you will get two overlapping images.
If you have a larger telescope, you will want to cut down the aperture, to prevent overheating.
You will be able to see sunspots on the disc of the sun and the growing bite of the sun hidden behind the moon (which will be otherwise unseen). You can practice on any sunny day, You should be able to see some sunspots, and perhaps faculae on any day.
Other alternatives are specially designed solar viewing glasses. They must be unscratched and meet ISO 12312-2:2015 standard. Welders glass is also possible if rated "14" (the darkest possible).
It is not possible to use any form of glasses with a telescope. It is possible to get an aperture filter, which may be useful if you have the right telescope, but the projection method is better if you want more than one person to view at the same time.
Any kind of improvised solar filter is unsafe. This includes: stacks of sunglasses, pop-tarts wrappers, exposed film and viewing reflections in water.
During totality, the sun is hidden by the moon, and so it is not dangerous to look at the solar corona during totality with the naked eye. If you had been wearing solar viewing glasses, be ready to replace them. You MUST put them back on before totality ends.
Photography is hard. The images of the solar eclipse are made with professional telephoto lenses and good deal of skill. Instead you can photograph the scene. A timelapse of the eclipse can be a very effective way to record the event, especially if you have some interesting foreground and background. The eclipse itself will be a tiny dot you can still document how the scenery and shadows change during the event.
I don't think you can get much better safety instructions for viewing than from NASA. Welder's classes are a pretty good choice. As for photography, I think Nikon would be a knowledgeable source, and they recommend a solar filter.
Astro solar filter is good. Baader Planetarium make this:
http://www.baader-planetarium.com/en/solar-viewer-astrosolar-silver-gold-(1pc-10pc-25pc-100pc).html
I have used this filter in front of a 4 inch refractor with no adverse effects.
I don't know where you are based but this product should be easily obtainable in the UK, USA and Germany. I have no affiliation with the company.
