Tutorial on how to setup and mark Home Position of the mount.
Home Position of the mount, also known as Parking Position, is the initial state from were we begin to operate our mount. Precision of the very first GOTO command for Star Alignment procedure depends on the proper Home Position of our mount. This position means that our counterweight shaft is pointed straight down and Dec Telescope Saddle is parralel to the RA axis and in this tutorial I want to show how to do it.
I'm always take my time to properly level my mount before any imaging / observation night. Since I don't want to have any differences in the field and before marking home position on my mount, I have also level it.
First, I place level to cover both legs and adjust they height until level.
Then I rotate the level and place it parallel to the North leg and adjust height until level.
Now, when I have my tripod level, I want to help my self next time in the field, or in case I forgot the level, I'm going to crash my second bubble level and stick just bubbles under the plate.
I'm doing so on all of the three sides. That would be good indicator to show me if my mount sunk into the ground after I'll put all the weight on it.
Next step is to place the head of the mount to it's place.
First we going to mark RA axis so we release the clutch...
and rotate the RA axis for 90°.
Next, we need to place the level on the extended counterweight shaft and carefully level the RA axis.
Then we release the RA hour scale and turn it exactly to 6 o'clock as shown in the image.
After we set the scale we need to return the RA axis to it's original position (Home Position). So we'll release the clutch and turn it back, so the counterweight shaft will again point to the ground.
But this time, we will pay attention to the hour scale and place the RA axis exactly to 0 hour and engage the clutch.
Now this you don't have to do, if you don't want, but I found this very cool to stick another bubble while my RA axis is exactly in the Home Position. Next time when I'm in the night and on the field, I don't have to read small grades of the hour scale, I'll just watch the bubble to properly position the RA axis.
But before sticking the bubble, I have also marked the mount it self, placing the ruler exactly parallel to the traingle mark and zero line and using permanent marker draw a straight line.
That will insure us, in case the hour scale will shift. This way you won't need to use all the process with the level again and just use this line agaist triangle marker on the mount.
Now we need to do exactly the same with the DEC axis. So release the DEC clutch and rotate it 90°
Placing the level in the saddle we carefully level it and engage the DEC clutch again.
Now we release the Dec hour scale and set it to 90° against the triangle marker of the mount.
Now we going to rotate the DEC axis back for 90° until the marker will read exactly zero.
It should look like this and this is the Home Position for our DEC axis.
Small problem though, you set the mount to Home Position after you have installed all of the equipment and balanced the scope. So reading the small triangle and scale under the scope is not so comfortable. And for solving that problem we going to mark the position on the side of the DEC axis when it reads now 90°.
Permanent marker will make sure you don't wipe it with hands while transporting the mount.
And we done here. Next time you in the field, level the tripod, align the prepared marks for RA and DEC axises and you in perfect Home Position.