by Bill Kramer, IAU WGSE, www.eclipse-chasers.com
Photographing a lunar eclipse, such as the one coming up on the 8th of October, is pretty easy if you have some basic photography equipment beyond a cell phone. Cell phone cameras are great at capturing people and scenery, but they do not have a good lens for longer focal length photography, and good lunar eclipse photography requires some focal length.
The good news is that you do not have to have a professional camera either. All you need is a camera with at least a focal length of 100mm (effective) and really no more than 1000mm. The longer the focal length, the better the mount you will require. For the 100mm variant a basic tripod will do the trick. As you get into the longer lengths a sturdier choice is best and as you go above 400mm the mount will need to track the movements of the Moon for longer exposures. For more details about mounting a camera for astrophotography, please visit http://www.eclipse-chasers.com/photo/Photo9.html
The camera settings need to be more than automatic. You will want to use manual settings for the lunar eclipse photography. The exposures needed to capture different aspects of the eclipse vary based on the focal ratio (or f/stop) and just what it is you are after. During totality much longer exposures are needed to catch the red brown color. Even longer exposures will turn the eclipsed Moon orange and expose stars in the background. Of course, the longer the exposure, the better the mount must be.
Here is a simple tip. Use the 10 second delay setting on the camera. Typically this setting is used when you use a tripod and you want to be in the picture. The ten seconds give you time to get from the camera to where you want to be in the resulting picture. When taking an image of totality with a modest camera of 100mm, set up an exposure of say 5 – 10 seconds. Next set the delayed image. Press the start and let the camera settle down on the tripod before taking the picture. The mount needs to be steady and not subject to a lot of vibration or swaying in the wind. Using this technique you can get great images of the eclipse and near by bright stars.
The image size is something to be considered for really striking lunar eclipse pictures. The longer the focal length, the more detail you can see in the lunar surface features. On the other side of the equation, the less focal length you use, the more scenery that can be incorporated. And during the total phase of the lunar eclipse, you can take a longer exposure to help capture that scenery under the eerie light of the lunar eclipse. Under 100mm the image of the eclipsed moon becomes an orange-brown dot in the final image. Enlarging it will not bring in much detail. However a landscape image that has lots of contrast could be very interesting in the light of a full lunar eclipse.
For more details related to lunar eclipse photography, please refer to http://www.eclipse-chasers.com/article/papers/tlePhoto.html