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Posts posted by steve_bham

  1. I use a laser collimtor plus a cheshire eyepiece to check the collimation on refractors I've owned.

    The laser collimator is used to check that the central axis of the focuser drawtube is in line with the optical axis of the objective lens - the laser spot appears in the centre of the objective lens as it exits the lens if all is aligned OK. If it's off to one side or another then the focuser needs to be tilted a bit.

    To check that the objective lens is correctly adjusted you leave the objective lens capped and put the cheshire in the focuser (no diagonal). With a light shining on the angled face of the cheshire, looking through the cheshire you will either see a single small circle of light reflected back up the tube from the objective lens which means the collimation is OK or you will see two small circles of light either touching or separated a bit which means the collimation is off and the lens needs to be tilted slightly. There used to be a nice web page explaining all this but it seems to have shut down now.

    Sorry if this repeats some of what Peter has already said !

    Thanks for that, can you recommend a laser and cheshire eyepiece that could be used on a frac?

    Sent from my GT-P5100 using Tapatalk HD

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