There are many factors affecting your decision as to what telescope and CCD camera to purchase.  This factor (especially when you are just beginning) should be one of the least important.

Resolution has two common meanings.  One meaning is the size of a CCD array (the number of pixels on the chip).  The other is the size of the smallest detail discernable by the telescope, or in this case by the telescope/CCD combination.

The resolution is limited by the size of the telescope, the steadiness of the atmosphere (the seeing conditions), and the size of the pixels on the CCD chip.  Assuming that most observing sites have approximately the same seeing conditions, the resolution is then a function of focal length and pixel size.  Choosing the right pixel size for a certain telescope can allow you to achieve the best possible resolution.

For the average imager, however, there are many more important factors.  Since most of us just want to take pretty pictures, the best resolution will not always yield the best field of view, etc.  Also, since you may already own a telescope that you will use for imaging the best CCD camera may be determined by a much simpler mathematical question:  how much can you spend?

For a detailed discussion of pixel size and focal length, why it matters (and why it doesn't), and other resolution-related issues, visit the CCD Theory Page.

Return to FAQs