How do I determine whether RA and DEC axes on a telescope mount are at right angles? How can I determine if optical axis of scope is parallel w RA axis
Testing for DEC and RA axis for perpendicarity and parallelism of RA axis and optical axis of scope
umm, how about try taking a picture of a bright star, then make a small move on the mount in one axis to move the star a few pixels and take another? If you then repeat with the other axis, you would have several images that you could overlay as layers in Photoshop/GIMP and get the line designating the trajectory of the star in each axis? I don't know how scientific that would be, but it should give you two lines (L-shape) that are quite close to perpendicular - I cannot imagine they won't be unless your mount is damaged somehow….
As for the telescope, are you asking about the polar scope built into it? If so, what model and brand mount is it?
As for the telescope, are you asking about the polar scope built into it? If so, what model and brand mount is it?
You might have a look at this small software: https://www.sharpcap.co.uk/conesharp
You are talking about orthogonality. The cone error software Geert mentions works well. Here is another approach from AstroPhysics which I have used with my AP mount that is quick and accurate.
Steps: ●Do a GoTo to Polaris. The star will not be in the center (eyepiece or CCD image) if you have any orthogonality error. ●●Put the star as close to center in Dec. with the N-S buttons. You will find that it will not move with R.A. with the E-W buttons. ●●Push a bit on the telescope tube in the R.A. direction, you will see the star move either toward or away from the center. ●●Determine which way the tube must move to end up toward the center. ●●Loosen either front or rear scope rings and slip a thin shim under the rings (.005” to .025” as needed).
Steps: ●Do a GoTo to Polaris. The star will not be in the center (eyepiece or CCD image) if you have any orthogonality error. ●●Put the star as close to center in Dec. with the N-S buttons. You will find that it will not move with R.A. with the E-W buttons. ●●Push a bit on the telescope tube in the R.A. direction, you will see the star move either toward or away from the center. ●●Determine which way the tube must move to end up toward the center. ●●Loosen either front or rear scope rings and slip a thin shim under the rings (.005” to .025” as needed).
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If you use SkyX Pro there is a nice feature in the autoguiding tab. When you calibrate the guidescope SkyX moves the RA and Dec axis. and you can see on the plot how orthogonal they are and how aligned that is with the 0 position (12 o'clock) of rotation.
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The other comments here got me thinking this afternoon that PHD2 has a tool for doing something like I was trying to suggest above and Gene is also suggesting I think.
https://openphdguiding.org/man-dev/Tools.htm#Star_cross_tool
But there are also a bunch of other useful diagnostic tools that it has built in for diagnosing mount control issues that might be worth looking at depending on exactly what problem you are trying to solve.
https://openphdguiding.org/man-dev/Tools.htm#Star_cross_tool
But there are also a bunch of other useful diagnostic tools that it has built in for diagnosing mount control issues that might be worth looking at depending on exactly what problem you are trying to solve.