Contrast and resolution of different telescopes
The following telescopes designs have been simulated to derive data about their relative levels of contrast and resolution. The method is described in a previous post, Calculating diffraction patterns. However, in summary, the closer the resolution figure is to zero, the better, and the closer contrast figures are to one, the better!
- Resolution is calculated as the radius of the first minimum of the diffraction pattern.
- Contrast is calculated as the ratio of light in a 1 arcsec radius of the focal point to the light in a larger circle (figures are given for 10 and 30 arcsecs). A perfect telescope would have a contrast of 1.0 in this scheme.
UPDATED (2015-05-05): The sampling has been greatly increased (9x) as has the resolution of the spot diagrams (2x), in comparison to the first set of data originally posted. In addition a number of bugs in the calculation methods have been resolved. I am reposting the data in batches, starting primarily with refractors.
| Telescope | Resolution (arcsec) | 10 arcsec Contrast | 30 arcsec Contrast | 
|---|---|---|---|
| Schmidt Cassegrain 150mm 37% Obstruction | 0.755 | 0.676 | 0.667 | 
| Schmidt Cassegrain 200mm 34% Obstruction | 0.575 | 0.867 | 0.858 | 
| Schmidt Cassegrain 280mm 34% Obstruction | 0.410 | 0.913 | 0.906 | 
| Maksutov Cassegrain 102mm 33% Obstruction | 1.130 | 0.675 | 0.661 | 
| Refractor 60mm 0% Obstruction | 2.140 | 0.563 | 0.549 | 
| Refractor 80mm 0% Obstruction | 1.605 | 0.748 | 0.735 | 
| Refractor 100mm 0% Obstruction | 1.285 | 0.836 | 0.825 | 
| Refractor 120mm 0% Obstruction | 1.070 | 0.854 | 0.845 | 
| Refractor 150mm 0% Obstruction | 0.855 | 0.858 | 0.850 | 
| Refractor 180mm 0% Obstruction | 0.715 | 0.891 | 0.884 | 
| Refractor 200mm 0% Obstruction | 0.640 | 0.912 | 0.906 | 
| Newtonian 150mm 0.5mm Spider 25% Obstruction | 0.800 | 0.761 | 0.751 | 
| Newtonian 150mm 1mm Spider 25% Obstruction | 0.800 | 0.759 | 0.746 | 
| Newtonian 150mm 2mm Spider 25% Obstruction | 0.795 | 0.752 | 0.734 | 
| Newtonian 150mm 0.5mm Spider 20% Obstruction | 0.815 | 0.792 | 0.782 | 
| Newtonian 150mm 0.5mm Spider 30% Obstruction | 0.780 | 0.726 | 0.716 | 
| Newtonian 200mm 0.5mm Spider 25% Obstruction | 0.600 | 0.881 | 0.872 | 
| Newtonian 300mm 0.5mm Spider 25% Obstruction | 0.400 | 0.915 | 0.908 | 
| Newtonian 400mm 0.5mm Spider 25% Obstruction | 0.300 | 0.939 | 0.933 | 

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