Friday, 25 September 2015

Total Lunar Eclipse - camera selection briefing

Small telescope (1300mm)

So you want to take a picture of the lunar eclipse? One question any expert will ask is what type of camera you have available for the event. Another is just what you want to photograph.

To produce a nice close up of the eclipsed Moon, you will want a small telescope or telephoto lens. The Moon appears to be about half a degree in size (yes, even during a so called Super Moon it appears that large). Using that information, the next step is to determine the field of view of your lens system and camera, which is a bit technical. This can be done with a formula (explained at https://www.eclipse-chasers.com/photo/Photo4.shtml) involving the size of your camera image plane (chip size) and the effective focal length. Cutting to the chase, I recommend a lens with a focal length of 200mm and more to show the Moon best.

April 2015 Lunar eclipse - EFL of 100mm
A frequently asked question is whether or not a camera phone can be used. The answer is an emphatic yes, just don't expect the greatest detail of the Moon and you will want to try several times before you get a nice image. The small lens will not capture much detail of the Moon however you can get great images of people and the eclipse. Just don't use the flash without warning others first!

When using a telescope or long telephoto lens you will need to manually set the exposure. Eclipses confuse automatic camera settings. As the eclipse darkens, longer and longer exposures will be needed to reveal details as seen in the image below. Both images of the eclipse were taken at roughly the same time, just different exposure settings. Note that the longer exposure washed out the illuminated surface while bringing out the eclipsed side where the shorter exposure shows the lit surface and a completely blacked out eclipse area.


A very nice to have is a tripod or fixed base for a longer exposure. Hand held images will show some blurring since it is nearly impossible to hold the camera perfectly still that long. Bracing yourself agains a building or wall might work if you are lucky but I strongly recommend a tripod or set it on the ground facing the right way and hope for the best.

Another trick is to use the delay feature (if available) on your camera. Point the camera at the eclipse and start the exposure. After a brief count down, the camera will take the image. The delay allows vibrations to settle and will result in sharper looking images. Using this method you can take an image that includes both yourself and the eclipse!

So the bottom line? If you want to try taking an image of the lunar eclipse, a nice big camera and lens on a tripod is best. But don't let that dissuade you from trying! I have seen plenty of great images taken with small camera phones. You just need to take a lot of images and have a lot of luck!


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