Saturday, June 22, 2013

Shooting the Supermoon

The so-called 'supermoon' was incredibly clear last night, so as my wife was heading off to bed and Cinderella's carriage was turning back into a pumpkin, I decided to grab my camera, zoom lens and tripod and venture out into the garden.

I thought it was going to be pretty straight forward - after all, with my Sigma 50-500mm last time, it was simple. But not with a shorter zoom lens - a 70-200mm lens with a 1.4x extender, giving me a 280mm reach.

When I first set up, got the tripod in the right place, lens at the right angle and the moon in focus, a massive band of thick cloud strafed in front of the moon, completely blocking it from view, and I thought the photo shoot would come to an abrupt end, but thankfully the cloud was moving pretty quickly.

I knew I had to consider a few things:
1.) The moon is really far away and I have only 280mm to play with, so whack the resolution up as far as it can go (22-ish megapixels on the 5D Mk III).  I can crop later on to see the detail.
2.) I need maximum clarity, so high ISOs are a no-no.  ISO50, 100, 200 are fine.  Stay away from 3200...
3.) Lock the tripod everywhere.  If this camera and lens tip over on the concrete patio, I will actually cry.
4.) Use a lens hood to stop streetlight, erm, light getting into the lens and creating weird and wonderful effects.
5.) Use mirror lockup and the 2-second timer facility to minimise any shaking, which would blur the moon.

The issue with shooting the moon is exposure.  Camera sensors are in no way as sophisticated as our eyes, so it's incredibly difficult in extreme lighting circumstances to capture what your eyes see.  The sensors in cameras try to pull colours towards middle grey, meaning that cameras try to overexpose for black (turning them grey) and underexpose for white (turning them grey).

(With that in mind, consider for a second what it is like to shoot a wedding, when many grooms choose black suits and most brides choose white dresses.  Nightmare.)

So when I pointed the lens at a mainly black sky with a moon the size of a pea, the camera just wanted to overexpose the entire shot.  This means that I might as well have created a black image and put a round circle of white in it somewhere, as the moon just goes completely saturated with no detail at all.

The answer to this dilemma is pretty simple - you underexpose the shot by about 3-4 stops or more to bring out the detail in the moon.  Don't worry about the sky being underexposed - it's black to start with!

There was a nice effect when light cloud around the moon was being illuminated, but it was almost impossible to get the moon correctly exposed while showing these clouds (and they were moving pretty quickly too, so the 0.4" shutter speed just blurred them across the frame):

1.) Ignore the camera's settings - it will give you a dark grey sky with a pure white moon.
2.) Underexpose by anywhere between 3 and 5 stops (or take a wild stab in the dark at the settings and go from there).
3.) Use a low ISO setting - high ISOs will prevent a really clear image.
4.) For stability, use a tripod, use the mirror lockup feature and set the 2-second timer.
5.) Set the camera to the highest resolution you have - then crop to see the detail.

1/60" at f/6.3, ISO50 at 280mm, cropped to a fraction of the original size

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