Cur­tains of light

NPhoto - - Special Feature -

What’s the ef­fect? This time seg­ment is prob­a­bly my favourite as the im­ages cre­ated at these shut­ter speeds are the stuff that Doc­tor Who is made of. Cap­tur­ing the psy­che­delic skies of an aurora bo­re­alis is some­thing that ev­ery pho­tog­ra­pher should ex­pe­ri­ence.

I’m lucky to ex­pe­ri­ence this spec­ta­cle ev­ery year when I lead work­shops in the Lo­foten Is­lands in Nor­way. It’s never a sure thing as it re­lies on the amount of so­lar ac­tiv­ity and clear skies. Check­ing the aurora forecast tells me if there is a chance of a de­cent show. The Kp-in­dex is a global geo­met­ric storm in­dex with a scale of 0 to 9. The higher the num­ber, the bet­ter the aurora. You don’t have to travel to the Arc­tic to see an aurora, though, as they are be­com­ing fre­quent as far south as north­ern Europe.

What’s the time? There is a par­tic­u­lar pro­ce­dure for cap­tur­ing auro­ras. The nor­mal ex­po­sure times are around 15 secs to 30 secs. The shapes of the auro­ras change quickly, so they would blend to­gether and the stars would start to elon­gate dur­ing longer ex­po­sures.

There is also a for­mula for fig­ur­ing out how long an ex­po­sure you can make be­fore the stars start to trail due to the Earth’s ro­ta­tion. It’s called the 500 rule, and ba­si­cally you di­vide 500 by the fo­cal length of your lens. For ex­am­ple, if you’re us­ing a fo­cal length of 24mm on a full-frame cam­era, di­vide 500 by 24 and you’ll get 21, mean­ing that go­ing no longer than 21 secs will en­sure the stars will be sharp points of light.

Use a wide-an­gle lens with the aper­ture set to its widest aper­ture. Fo­cus man­u­ally and set it to in­fin­ity. The hash mark should be set to the mid­dle of the in­fin­ity mark on the lens. I al­ways make an ex­po­sure then check the fo­cus at 100 per cent on the LCD. The ISO set­ting can be any­thing from ISO400 to ISO4000 or more, depend­ing on the amount of moon­light. I’ve used ISO400 with a full moon where it lights the land­scape. No moon will al­low the aurora to show up bet­ter, but I like to have some de­tail in the land­scape. The usual go-to ISOs are ISO1600 to ISO3200. These give a short enough ex­po­sure time to cap­ture the aurora.

When de­cid­ing where to pho­to­graph your aurora, look for a land­scape fea­ture that will com­ple­ment them. I shot this im­age from a beach; the wet sand cap­tured the re­flec­tions of the moun­tain and aurora per­fectly.

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