Simplified Astrophotography

(Philip van Heerden)

Digital astrophotograpy is no longer the sole domain of the privileged. Not anymore is sophisticated equipment needed to obtain decent enough images to make a night out with a relatively inexpensive telescope, a pleasurable experience. The afocal technique for acquiring images with an ordinary run of the mill digital camera has made a big difference. By simply holding the camera up to the eyepiece of the telescope and then clicking away, quite acceptable pictures of the moon and inner solar system planets can be obtained. Of course, if you have a shaky  hand like I have, a clamp to hold the camera still against the eyepiece is a must. Not only does it prevent movement of the camera, it also ensures that the orientation of all images are constant especially when stacking of a series of pictures is needed to improve the quality of the shots. 

I am using a Fujifilm Finepix 2600 camera with a maximum resolution of only 2 Megapixels and a 3x optical zoom, on a homemade 9" Dobsonian reflector (F 8) with a Plossl 25 mm or an 18 mm Celestron wide angle eyepiece. Image stacking of planetary images is done by means of Registax, Image Stacker or by hand using Microsoft Picture-It. A cut-out of the first image is made whereupon a second image is positioned exactly over the first image. A 50% transparency setting is used and the second image appropriately enlarged. A cutout of the combined images is now made and the entire process repeated with a third image until all the images have been stacked. The brightness and contrast of the final cut-out is then digitally optimized.

I use the following method to take pictures of the moon, planets and other bright bodies. My camera is always on Auto which means that the flash goes off with every shot. This keeps the shutter speed of the camara fixed and minimizes motion artifacts. I focus by pressing the shutter button in halfway with the object to image in the viewfinder. As soon as the object is well focused I press the shutter button way down. The flash goes off but does not have any effect on the image. When the object like a planet is not in the middle of the brackets in the view finder, I receive an autofocus warning.

Although there is a good clamp for a camera available commercially at  http://www.have2have.co.za/viewimage.php?ID=828 , I use a home made model. (see pictures below)

Click on the small images to enlarge

The "Spider"- a 9" Dobsonian used for all the images on this web Page.

Contact: Philip van Heerden