A reflecting telescope (Fig. 25–22b) has a radius of curvature of 3.00 m for its objective mirror and a radius of curvature of -1.50 m for its eyepiece mirror. If the distance between the two mirrors is 0.90 m, how far in front of the eyepiece should you place the electronic sensor to record the image of a star?
Figure 25-22 (b) the Cassegrainian focus.
Source: Giancoli, Douglas C., Physics: Principles with Applications, 7th Edition, 2014.