Quote:
Originally Posted by pmrid
The trouble with digital inclinometers is that they need to be accurately zero’d and even then, most report accuracy in the +- 0.1 to 0.5 degrees range. Not all that encouraging if you want to use it for PA levels of accuracy.
The other problem is that we have no visual guide for dead-centering the pole and we also have to make some allowance for atmospheric refraction around the pole so that inclinometers are at best an approximation. The degree of refraction is a function of height and several other things but, for example, at 10 degrees, it can be as high as 5-6 minutes of arc. At say 27 degrees it would be in the vicinity of 3 minutes.
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I did say as a check, use the inclinometer.
I also use a compass stick to get the true north close (and in the middle of the az adjustment range for later polar alignment)
-- a compass still as I like real magnetic compasses and I adjust for the magnetic declination with the stick keeping the compass away from any influence of the tripod
Good info putting numbers re relating inclinometer accuracy to the sky. I must dig into that. I'd also be interested in the impact on compass accuracy and true north. An advantage of living south (in Sydney) where even less atmosphere to look through.
I use SharpCap to drive a polemaster camera to do polar alignment with the atmospheric compensation turned on so hopefully less impact. I intend to try the NINA polar alignment if we ever can get clear skies again.
It's more out of curiosity as I do a small model the sky anyway with my Astro-Physics Mach2, turn tracking on and can image without guiding if I want but like the graphs from PHD2