Polar Alignment for Southern Hemisphere
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Polar Alignment |
For the German Equatorial Mount, that we use to take star photos from, to accurately follow the motion of the stars it needs to be pointing in the direction of (aligned with) the South Celestial Pole (SCP) the region in the sky where the stars appear to rotate or the part directly above the south pole, sadly even form a dark sky region like Tekapo you can't see anything in that part of the sky because the stars are to faint, so how do we find it? Most german eqitorial mounts are equipped with a polar finder scope which luckily for us gathers more light than you would normally see with your own eye - here is what I would be looking for
Thank you Mr Masui for this picture
As you can see from the picture its only showing 2 degrees from the SCP so the initial placment of the mount is crucial, the more accurate this alignment is the longer you will be able to expose your star photo for without getting star trails, even if you were using an auto guider. Even 1 degree off (out of the inner circle) and your exposure time would have to be less than a few minutes for a good photo (one without star trails or oval shaped stars) for this reason spend time to get this correct as our target exposure times start from 4 minutes (using just a normal lens f/4 ISO 1600)
Actual photo of the SCP taken with a 85mm camera lens from Tekapo, cropped to get a similar angle and field of view
Once the alignment is correct anything based on top of the tracking mount will follow the motion of the stars regradless of the direction you choose to point your camera, how much you zoom in or how long you expose for. Now the next challenge is for you to get the focus correct.