AstroBee wrote: ↑Sun Aug 07, 2022 1:54 am
If you are only a few minutes south of the equator then your R.A. angle is way off in your setup unless I'm not 'reading' your photos right???
Well, that's an interesting observation. I certainly cannot claim expertise in telescope mount construction. So let me try to understand and comment.
The business of a few minutes south of the equator for this particular dark site where I was imaging is indisputable. I am very sure I got the proper latitude and longitude from my phone locator
app. Besides, I have been living in this area for 30 years. So I know the territory.
I have no idea what you mean by the phrase "R.A. angle". I normally think of a mount being polar aligned to both altitude and azimuth. As far as I know, this means making the axis of rotation for
RA rotation coincide (align) as closely as possible with the earth's axis of rotation.
For a geographical location near the equator, the axis of rotation for the mount has to be close to level with the ground.
The axis of rotation for the
RA rotation on my mini-
EQ mount is the horizontal steel bar in the pictures above. The counterweights hang down off of that horizontal bar (riding on a perpendicular blue bar) and the camera is mounted on top of that. (One of the CWs
is an old piston from a car engine...
)
The
RA rotation is controlled by a stepper motor and a gear train (see the BIG gear on one side of the mount connected to some smaller gears). (It took incredible effort to get that big gear centered on a block of wood...)
I can start my imaging session at any
RA position that allows the camera to point towards the sky -- all the way from east horizon to west horizon.
I can rotate the camera to any
DEC position -- all the way from north horizon to southern horizon. But I have to do that manually and then it remains fixed during an imagining session.
In the pictures posted, the camera is facing a slightly northern
DEC position and the
RA position is towards the western horizon.
One thing I am sure of -- as you can see in the images above -- is that I got fairly round stars with 30s light frames using a 180mm camera lens. That actually pretty hard to do if you have ever tried.
If you still think there's a problem, please let me know. I would be surprised if I have some big problem. But then again, I have made my fair share of really stupid mistakes over the years.
BABO