Piggyback method of astrophotography
Posted: January 5th, 2008 by HrAstro
Piggyback photography is the easiest form of deep-sky astrophotography. It involves attaching your camera on your telescope and shooting through a camera lens while the scope tracks the stars. Everything here is easier. Polar alignment is less critical, focusing is (usually) easier...
For this method you will need:
- Motorized EQ (equatorial) mount
- Guide eyepiece (although there are much more advanced solutions, but more expensive)
- Camera with the possibility of longer exposure
All you need is to align the mount to the celestial pole, use some of the method to mount the camera to the telescope and point it to the desired object (those are usually the whole constellations and more). And find a bright star trough the guiding eyepiece. Now you just need to make sure that the whole setup is well balanced. Arrange the settings of the camera, take the mount controller and start the exposure.
For the whole time of the exposure we are hanging on the bright star that we previously found in the center of the guide eyepiece. This process of holding the bright star in the center of the guide eyepiece, using the mount controller, is called «manual guiding», and the precision depends on the focal length (zoom) of the camera lens. Sometimes with good celestial pole alignment and a shorter focal length of the camera lens (for example somewhere less than 70mm) there is no need for guiding because the mistake is too little to be noticed on the photo. So you should experiment with one or two exposures in order to make it easier for yourself.
One or two exposures? Why?
Not just one or two, you should use as much exposures you can because long exposures make so cold «noise» and all kinds of artifacts. In order to avoid that we take as much exposures as we can and do the process of stacking images, but more about that in the upcoming articles:
Why Stack So Many Frames?
How to stack images using IRIS softweare
Examples of images taken with piggyback method: