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When viewed using my reflector telescope, the image, for example the moon, is flipped over and upside down (reflected). Therefore I need to do the ‘opposite’ movements when I want to align something. Is there something I can do to correct this, or is that part of using a reflector, or am I doing something wrong ?

e.g. : The moon’s crescent is currently to my bottom right, however, when viewed through my 'scope, it’s on my top left.


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An erecting prism will both flip the image right side up and restore left-right orientation. The problem with using one in a reflecting telescope is that because they're several inches long, you'll need to rack your focuser several inches farther in in order to place the eye-piece at the correct location to bring the image into focus. In many cases there won't be enough available infocus to do this unless you modify the telescope to bring the primary mirror closer to the secondary mirror/focuser assemblies (and then you might need a larger secondary to keep wide angle eyepieces fully illuminated at the edge). This isn't a problem for refracting telescopes since it would replace an existing 45/90* diagonal which would have a similar length.

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A right angle prism will invert the image along the axis of the prism but I would suggest just getting used to the reverse movements. Remember to keep your eye on the target and you can't go too far wrong...

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use a right side prism and place right ahead of eyepiece then it will correct! np

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