REVEALING TOTALITY IN HDR

PHOTOGRAPHING SOLAR ECLIPSES is one of the most challenging forms of astroimaging. It requires a great amount of advanced planning, from organising the equipment you tow along on your voyage towards totality, to recording a series of exposures that capture the huge range of brightness displayed by the Sun’s ethereal corona. It’s even trickier if you hope to reveal complex magnetic loops that are hidden within the corona. Fortunately, digital photography has made this type of high-dynamic-range (HDR) imaging a bit easier. Here’s a technique I use with Adobe Photoshop that works on solar eclipse photographs taken through al=most any lens or telescope.

A good plan

Part of the trick for revealing the entire dynamic range of the solar corona is to shoot bracketed exposures. Because the corona spans an extremely wide range of brightness, it’s impossible to record all the coronal detail in a single exposure. Prominences visible along the eclipsed Sun’s limb are best captured in very short exposures of typically 1/500 second or less in an f/5 optical system, whereas photographing the outermost extent of the corona requires keeping the camera’s shutter open