Hermes Posted January 9, 2021 Report Share Posted January 9, 2021 (edited) When I was able to get both planets in the same view with my telescopes, I drew proportional sketches of the conjunction. With a field-of-view, for example, of 2.42 degrees, I used circles of 2.4 and 4.8 cm. I developed a personal technique of being able to view with both eyes open so that I can hold a centimeter scale at a convenient distance to guage separations. I have used this for binary stars, also. ' Images are reversed right and left. Saturn was to the West (Left) of Jupiter. That is an artifact of the refracting telescopes. We correct that with prisms for binoculars ("field glasses"). With astronomical objects it is not that critical and we often just indicated N-W or whatever is convenient. On the night of closest conjunction, the sky was overcast. I could make out the planets because I knew what they were, but nothiing was distinct. I could not see the rings of Saturn or the moons of Jupiter that night. As for the annotations. Consider the notes added to the image directly above. 70mm is the diameter of the objective lens. F/10 means that the focal length is 700 mm. The viewing power is found from the focal length of the eyepiece (17 mm) divided into the focal length of the objective: 700/17 = 41+. In addition, I used a 2x Barlow lens, which effectlvely halves the focal length of the eyepiece, doubling the magnification to 82X. The field-of-view (FOV) is just under 1 degree: 52m 34s. That is based on the standard ("Ploessl") eyepiece field of view of 50 degrees at the higher power. (Georg Ploessl was a 19th century maker of optical instruments. His designs for eyepieces became popular in the late 20th century when the hobby of astronomy exploded in response to the US-USSR "space race.") Edited January 9, 2021 by Hermes Grammar and syntax. dream_weaver and Boydstun 2 Quote Link to comment Share on other sites More sharing options...
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