Telescopes and Astrophotography
From SkyInsight
Contents |
Overview
Knowing what the abilities and limitations of a telescope are just as important as the abilities and limitations of the camera. One key is the telescopes focal length. In addition, each telescope design had it's advantages and disadvantages. There is no perfect telescope for imaging. You need to use the right kind of telescope for the type of image you plan on doing.
Focal Lengths
Different telescopes have different focal lengths. When it comes to imaging the focal length plays an important role. Telescopes with short focal length will have a wider field of view and thus tolerate minor alignment or tracking issues. Telescopes with long focal lengths narrow the field of view giving you a closer image of an object but at the expense of more accurate alignment and tracking. In addition, good seeing (or better) is required when imaging at longer focal lengths. Seeing has no effect on imaging with a short focal length.
Telescope Designs
- Small APO Refractors
- Advantages
- Very good optical quality
- Great for wide field imaging
- Very portable
- Sharp images with good contrast since there is no obstruction in the light path
- Disadvantages
- Wide field of view
- Smaller aperture means less light gathering power
- Advantages
- Achromatic
- Advantages
- More affordable then apochromatic telescopes
- Disadvantages
- Requires the use of filters for color correction and finer focus
- Requires refocusing with each filter wheel
- Advantages
- Large APO Refractors
- Advantages
- Nice balance of aperture (i.e. more light gathering), field of view and magnification
- Disadvantages
- More expensive
- Advantages
- Reflecting Telescopes
- Advantages
- Disadvantages
- Newtonian Telescopes
- Advantages
- Disadvantages
- Maksutov-Newtonians
- Advantages
- Disadvantages
- Schmidt-Cassegrains
- Advantages
- Disadvantages
- Maksutov-Cassegrains
- Advantages
- Disadvantages
- Ritchey-Chretien
- Advantages
- Disadvantages
