He used a 5in refracting telescope equipped with a hydrogen-alpha solar filter as he tracked the 'smile', known as a filament, for five days.
Times, Sunday Times
The photographer has a solar filter to take the pictures, she said.
Times, Sunday Times
He made 44 exposures on a single frame of film all taken from the same location with a solar filter.
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People used special eclipse glasses or solar filters on telescopes to witness the event.
The Sun
Once you remove the solar filters, the binoculars will operate like a normal pair.
Smithsonian Mag