…And How To Do It
In this my latest blog, I have taken advantage of the recent clear nights for some astro photography, specifically shooting the moon. It’s true however, that as I sit typing this in my studio, there’s a howling gale, but at this time of year, if we do get those still clear nights, the night sky is there in all its sparkling, clear and starry glory.
What Moon Phases to Shoot?
When I shot the photographs of the moon shown here, it was the night of January 19th, a crisp and frosty minus four degrees with the moon yet to get to “full”. In fact the technical term for the phase of the moon I was shooting is Waxing Gibbous. Yep, I know, weird, but despite what you might think, it’s better to shoot the moon before it’s full, as I’ll explain. Starting from the New Moon, which is when the moon is completely in shadow, so it cannot (usually (or easily) be seen) the moon phases progress to Waxing Crescent and then First Quarter. Next you get Waxing Gibbous (my shots here) and then the Full Moon. Then comes the Waning Gibbous, the Third Quarter and then Waning Crescent and finally back to the New Moon. So, why not shoot the full moon?
The answer to this lies in the shadow across the moon’s surface or the penumbra or the edge of the shadow. A full moon has no shadows so details such as craters and mountain rages have no edge definition; some of the best details that are on offer are left in a very harsh flat lighting. By shooting the moon when there’s a partial shadow (the penumbra, as mentioned earlier) shadows are cast from crater edges and lunar mountain ranges so you get a better chance of capturing the all important finer details. And of course, no matter what your camera set up (see Equipment below) this is vital to a successful moon shot.
A camera is the first thing you’ll need here of course and one with a high-resolution sensor is best but absolutely essential, as you’ll see shortly. If you have a long telephoto lens than that helps too, or a telescope and adapter, which you can mount on your camera, then all good. But I’m concentrating on using non-telescope gear here as those with a telescope and fitting adapters for their cameras, probably already do astro photography.
I used my tripod-mounted Olympus OM-D EM-5 Mk II fitted with my Zuiko 35-100mm F/2 zoom lens and the EC20 2x tele-converter. Both of those were mounted on the MMF-3 lens adapter so that I could use my FourThirds optics on my Micro FourThirds body. That lens and camera combination means the camera provides a 2x crop factor on the lens’ displayed focal length, in effect making it a 70-200mm lens. The 2x converter doubled that to a 140-400mm lens, so pretty respectable but I can do even better. Because the EM-5 MkII also has a built-in digital tele-converter giving another 2x magnification; actually this is just a crop on the sensor but done in camera and so there’s nothing stopping you from shooting at whatever your optics give you in terms of focal length, then cropping in on the image later on PC, but I wanted to get as much sorted in camera as possible.
That all gave me the effective focal length of between 280mm and 800mm and while the camera’s native resolution of 16-megapixles is good the digital teleconverter mode I have used here reduces the effective resolution to about 6-megapixels, which while not massive, is more than enough for most purposes, plus that 800mm equivalent focal length gave me a good-sized moon image in the frame too. If your camera does not have a 2x teleconverter (or a digital zoom mode, which might be worth trying out) don’t worry. As I mentioned, there’s nothing wrong with a crop later on PC, but you just have to make sure you fill the frame as best you can, you used the best quality setting you can and the maximum resolution you can. The next step is to make sure you get a sharp image.
Expose to the Moon
Cheap laughs aside (expose to the moon indeed) the next step is vital. You’ll need a tripod, the sturdier the better, to help keep your camera as still as possible. Also, the greater the magnification you use (so the longer the focal length) then the faster the moon will cross the frame as the Earth rotates. In fact, at my 800mm focal length, I could see it move. Incidentally, to those wondering (or with the same camera as me) I tried the 40-megapixel high-resolution mode, which combines eight images together inside one second to give the enhanced resolution. But even that one second allowed the moon to move enough in the frame to lose all the moon’s finer details. I could not use my camera’s high-resolution mode.
Back to the exposure information. You might be surprised that photographing the moon needs a faster exposure than you might think. First I Aperture Priority mode where I can control the aperture settings, the camera controls the shutter speed. I then set my metering to spot metering, to measure only the light from the moon’s surface. At ISO 200 that gave me a shutter speed of 1/640th-second at F/5.6, a much faster shutter speed than you might expect, but one that helps you to keep the vagaries of any movement to a minimum as you take the shot. If you can your camera to use its self timer or use a remote release, that helps reduce vibrations too and if you can lock up the mirror (or in my cameras case, use the vibration reduction setting) then activate those too. If you’re able to use a shutter speed faster than your focal length (so in my case here, it would be one faster than 1/800th-second) this helps reduce camera shake too, but you’d need change the ISO (make it higher) to gain the extra shutter speed. That’s great, but the downside of using higher ISOs is it can introduce unwanted image noise that reduces the finer details.
Take the Shot
Then all that is left to do is take the shot. I used the camera’s self timer and the display to check things; I took around 80-shots, but the ones shown here are about the best balance between detail and noise and exposure. I tried an HDR shot (I took four exposures at F/4, F/11, F/14 and F/20), combined them in Photomatix Pro and that image is below here. But it does not really offer up anything new in terms of detail and if I’m honest, it looks worse than the straight shot shown above.
And that’s it. I hope you like the shots and found this little tutorial useful. Winter nights really are the best to take moon photos (well the crisp and clear ones anyway) so get out there and get snapping.
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