“This is an old style doublet Fluorite Apo, where the Fluorite is the inside lens. The remaining color is what you will find when starttest at very high powers. The defocused images do show nearly identical patterns. The lens is smoothly polished and has an outstanding spherical correction. I have tested maybe 10 pieces of this type of telescope during the past 10 years and this lens is one of the best I have seen thusfar.”.
Markus Ludes (APM-Telescopes)
Cut out effect
This image shows a small area cut from the image due to the secondary mirror of the Maksutov Newtonian collimator setup.