Shooting the moon - photography technique

The film American Werewolf in London was on TV again and on the same night I was out in the back garden shooting a full moon. I wasn't expecting to hear any wolves, although the sound of noise I made setting up the tripod was enough to set the next door neighbour's dog howling! I needed a tripod to keep the Ricoh i700 digital camera steady.

Anyone who's ever tried to take pictures of the moon may now be wondering how I expected to get a decent image of the moon using a digital camera, especially if you're aware that this Ricoh, like many digital cameras of its type, has a 3x zoom that is the equivalent to a 35-105mm zoom on a traditional camera. There is a digital 3.2x option that takes this up to 336mm, but again not enough to fill a frame with the moon. So why was I wasting my time?

The answer was a trial. There's currently a large amount of excitement throughout the Internet newsgroups about a technique known as Digiscoping. This technique is where you connect a spotting scope with a digital camera to create a super telephoto lens and there's an article by bird photographer, Jason Smalley, on the ePHOTOzine web site.

As I sat watching the film I had an idea and dug out my pair of compact binoculars. Unlike a spotting scope, that costs 400 to 500, these compact Olympus 10x25s cost about 120 and can be used for general viewing. But would they double up as a super-duper telephoto?

With the camera mounted and pointing at the moon I positioned the binocular eyepiece over the camera lens and found the answer...Yes! The moon appears on the i700's viewing screen as a decent sized white ball. The 10x power of the binoculars has converted the camera's 105mm into a 1050mm telephoto. Now all I needed to do was sort out the various technicalities to capture it on digital film.

Also because most digital cameras have LCD previews you can clearly see what will be recorded on the CCD and then review what was captured when you've taken the shot. This is a real benefit when shooting trick exposure such as the moon where the dark surrounding night sky can quite easily fool the exposure, and in the Ricoh's case it did. The first shot was a white blob in the centre of a black canvas. There are two way's round this. One is to use exposure compensation and the other is to take the camera of auto and use manual exposure. Some digital cameras have one or both of these options. I used the exposure compensation control, setting it to -2 to give two stops less light reaching the CCD.

Even with such magnification the moon still looked small in the frame so I had two options, use the camera's digital zoom or crop the image and magnify using the computer later. The 3.2x digital zoom on the Ricoh only works at the 640x480 setting so you gain the magnification, but lose resolution. Keeping the camera at the high 2048x1536 resolution setting creates a far larger file, which, once cropped to the same magnification as the digital zoom delivers a larger 788x564 pixel image.

Picture taken at 2048x1536 resolution.

Same image showing cropping area.

Cropped version is 788x564 pixels.

Now we need to get the focus right. Although the binoculars where focused on the moon using the naked eye the image doesn't appear sharp on the camera's viewfinder and that's because the CCD is at a different distance to the eye and you have to take into account the camera's optics. Once again the LCD proves perfect here. You can focus the binoculars as you view on the LCD. When the image appears at its sharpest stop. The camera's autofocusing will probably also need turning off. The Ricoh searched each time an image was taken, which becomes frustrating and is an extra drain on batteries, but if the camera doesn't have a manual focus you'll have to put up with this.

Moon with brightness and contrast adjusted.

Then apply a small amount of sharpening to bring out detail in the craters and contours of the moon. Again basic sharpening is available with all image editing programs or use the unsharp mask for finer control in more advanced packages.

Final shot has a small amount of sharpening to make the surface detail more refined.

The shots I took could have been better and will be next time. I've mentioned the tripod mounted camera, but the binoculars were hand held over the front of the camera. I will now work on developing a clamp support to allow them to be held in position removing any possibility of camera shake.