Date: September 23, 2010
Title: Howling at the Moon
Podcaster: Richard Wright
Links: Evening Show – http://www.eveningshow.org & Software Bisque – http://www.bisque.com
Description: Richard provides tips for observing the Moon.
Bio: Richard S. Wright Jr. is a Sr. Software Engineer for Software Bisque, and an avid amateur astronomer. When not moonlighting with one of his six telescopes, he also teaches a night class on computer graphics programming at Full Sail University near Orlando, FL, and is the lead author of the OpenGL SuperBible. He can be contacted at opengl@bellsouth.net.
Today’s sponsor: This episode of “365 Days of Astronomy” is dedicated to PARI, the Pisgah Astronomical Research Institute, home of “Smiley”, the worlds most beloved radio telescope. I’d also like to wish PARI’s education director, Christi Whitworth a happy birthday today. Keep up your good work there Christi!
Transcript:
Howling at the Moon
Photographing the full moon, without a telescope.
Welcome to the 365 Days of Astronomy pod cast for September 23rd, 2010. My name is Richard S. Wright Jr. I’m an amateur astronomer and photographer, and a software engineer for Software Bisque, where I get to help make some of the worlds best astronomy software products.
Today I’m going to talk about howling at the moon. Well, metaphorically that is. I would never admit to actually howling at the moon like some lone coyote or wolf, but I do love taking pictures of the moon, especially the full moon. A small web gallery of images taken using some of the techniques I’m gong to talk about is available at www.eveningshow.org.
Mankind has been fascinated and enthralled by the full moon for millennia. The sight of the full moon evokes a strong emotional response varying from foreboding, fear and mystery, to love and romance. Legends and stories about the full moon abound in folklore. We’ve kept time, planted our crops, and watched for werewolves, all around the cycles of the full moon.
While just about any camera can capture a nighttime scene that includes the full moon, I am going to restrict my discussions to modern digital cameras. Whether it’s a simple point and shoot hand held, or one of the more advanced DSLR’s.
Primarily, this podcast is going to be about taking a picture of an outdoor scene that includes the full moon. This is best done shortly after moonrise, or before moon set when the moon is low on the horizon and appears near or over some other interesting landmarks. Occasionally, a shot up through some trees showing the moon among some clouds can be interesting too.
Whether it’s a point and shoot camera or a full-blown DSLR, the single most important accessory you need for any kind of nighttime photography is a tripod. A steady camera is essential for crisp in focus images. A second, and often overlooked accessory is a remote release cable. Even with a tripod, when you press the button to open the shutter, you move the camera ever so slightly, which will cause even the most carefully focused image to appear soft or blurry.
What if your camera does not have an option for a cable release? Many point and shoot cameras for example do not, but what they do usually have is a timer feature. You know, so you can line up your friends, set a timer, and then go and run to get into that group shot before the timer goes off. If you can’t use a cable release, a timer works as well since you won’t be touching or moving the camera when the shutter fires.
For a point and shoot camera this is about the best you can do, and terrific shots can be had of well-lit nighttime venues, with the full moon featured prominently in the background. The moon itself is bright and will show up, even against a very bright foreground scene. You might even employ your camera’s flash to help light the foreground objects.
For the best results, you really need a camera that features a “manual” mode that allows you to override your exposure settings. A camera that “does everything for you” is not going to cope as well with a bright moonlit sky and a dark surrounding terrain.
The most important setting for nighttime photography is exposure time. The longer the shutter is open, the more light that is gathered for your image, and the brighter it will be. A moonlit landscape image of 30 seconds to one minute in length can appear almost like daylight, but with a surreal feel to the scene. Framing the moon in such a scene only adds to the effect. Bear in mind through, that exposing the moon for this long will overexpose it, and it will appear as a bright white light in the sky. Throw in some clouds, and again, this has a very artistic feel to it.
Most digital cameras have an image preview feature, which allows you to adjust the exposure time and check the results to suite your tastes. You could even take multiple pictures, one exposed for the moon, one exposed for the foreground objects, and then combine them with your favorite image editing software.
Another important and similar setting is the ISO. This setting determines how sensitive to light your film or camera sensor is. The higher the ISO number, the more sensitive to light your camera will be. The trade off for higher light sensitivity though is noise, and high ISO exposures at night often have an unpleasant grainy appearance. For best results, shoot for a longer exposure with a lower ISO rating rather than a shorter exposure with a high ISO rating.
Something else to consider though is that often things like trees, and people won’t hold perfectly still for a lengthy exposure. If the wind is blowing, or even if there is just a slight breeze, trees are going to sway and will blur. A good composition technique is for either the foreground or the background to be out of focus anyway, so sometimes this is not a problem when your goal is an in focus moon, with a defocused foreground.
The final manual setting that you may wish to adjust is the f/ratio. Big numbers mean a small opening in front of the shutter to let less light in. Smaller f/ratio numbers mean a larger opening, which lets in more light. This sounds great for low light conditions, but there is a trade off. When the aperture (the opening that allows light in) is very large, you get a very shallow depth of field. What this means is that only a portion of your scene will be in focus. The smaller the f/ratio (and smaller opening remember), the more of your scene will be in sharp focus. Typical landscape photographs are taken with very high f/ratios to make as much of the area as sharp as possible. This is of course counter to our goals at night when we need more light to get a good exposure. This is why a tripod is essential.
Another interesting, and sometimes desired effect of high f/ratios is it creates a starburst effect around bright light sources, such as the moon, or streetlights. With a high enough f/ratio, you can even get a good focus on the moon itself, and the surrounding landscape.
Remember though that the moon is very bright and a good exposure of the moon itself is going to take much less than a second. Other objects at night on the other hand will often take several seconds to capture unless they are very well lit. Most of the time it will not be possible to capture both a well-exposed moon, and a well-exposed foreground scene in a single exposure. Combining separate images of different exposures or focuses is not always necessary to get an interesting moonscape though. Dark foreground objects silhouetted against a moonlit sky are interesting and striking all on their own.
Many people are actually quite surprised at just how small the moon really is in the sky. A wide-angle view of a park or some rooftops with the full moon in sight often reveals just how small the moon actually is. A better composition can be had sometimes by zooming in on the moon as much as possible, while still capturing some foreground objects. With a modest telephoto lens in the range of 200 to 300mm, the disk of the moon shows a good bit of detail. The man in the moon, the various seas, many craters, and ray systems all become more apparent and make for an interesting composition.
One of my favorite compositional techniques is to catch the moon on a partly cloudy evening. A few nearby clouds, or a thin transparent cloud deck lit by the light of the full moon makes for a dramatic skyscape. Overexposing the moon slightly, to catch some foreground trees or buildings makes for a striking and mysterious scene. In these cases, I tend to focus the foreground objects, and let the over exposed moon be slightly out of focus.
When using a telephoto lens, I like to have a sharp and crisp lunar image, and slightly blurred foreground objects. This draws the eye to the object of interest, in this case the moon itself. Living in Florida, I have an abundance of such images with the silhouette of a palm tree nearby. Any far off, but distinctively shaped landmark will do however.
Occasionally, I resort to the ultimate cheat. I will set my camera on a tripod, and expose and focus for the moon itself. Then I’ll take a second picture with the exposure and focus optimized for the foreground objects. Using Photoshop, I’ll then combine the two pictures for a realistic view that can be captured by the human eye, but not with a single photographic exposure. The tricky part here is to not over expose the moon too much in the second shot, or it will bloom (get bigger) too much and make it difficult to mix the two pictures together.
Well, that’s all for this podcast. All you need is a digital camera, a tripod, and some imagination for your own lunar-imaging projects. I hope you’ve picked up some useful tips for your own adventures howling at… um, photographing the full moon.
End of podcast:
365 Days of Astronomy
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