East Heavy

[DarwinAstro]

I keep hearing the term East Heavy and hoping someone can enlighten me.

So.......
- I have an EQR6 in the southern hemisphere.

- To my knowledge east heavy refers to the mount's gears being engaged which in turn will aid in reduced backlash.

- So the confusion for me lies in this....

If the mount is in the northern hemi it will track east through north onto west, meaning right to left.
Therefore, the opposite will apply for the southern hemi.
The mount will track east through south onto west.

Therefore, the gears must move in opposing directions.

Does this mean in the north it is East heavy and the south, west heavy?
As usual I may be looking for a problem here that does not exist.

[Stephane]

The “left & right” positions would obviously change depending on whether you are in the northern hemisphere facing the North Celestial pole or Southern Hemisphere facing the South Celestial pole. When facing the celestial pole, East is to the “left” down here, but to the “right” in the northern hemisphere.

However, stars appear to rotate East to West regardless of which hemisphere you are in. So going slightly East heavy applies to both hemispheres, regardless of what’s left or right. True, rotation is different in both hemispheres (clockwise South; anticlockwise North), but this does not change the fact that stars are rising in the East, you are rotating away from the East, and so you go slightly East heavy.

Hope that clarifies things.
Stéphane

[Startrek]

The term “East Heavy” generally relates to the Ra axis of your mount and the logic behind it is to keep the Ra motor drive gears engaged or meshed at all times when tracking to reduce slop and play thus improving tracking and guiding ( also improves Ra tracking for belt driven mounts like my two EQ6-R’s and my EQ8-R )

East Heavy (Eastern side of meridian)
Scope on the west side
Counterweights on the eastern side
Balance mount level in Ra and Dec
Place mount in home position then slightly move counterweights down shaft towards the ground between 5 to 15mm depending on mount and payload

East Heavy ( Western side of Meridian)
Scope on the east side
Counterweights on west side
Balance mount level in Ra and Dec
Place mount in home position then slightly move counterweights up shaft towards mount body between 5 to 15mm depending on mount and payload

If your mount has more than one counterweight, usually you only have to move one counterweight slightly up or down

To be honest I’ve never bother using East Heavy on the western side of the meridian , I’ve just left it slightly east heavy on the eastern side for tracking towards the meridian and after a meridian flip on the western side descending towards the west.I haven’t noticed any issues with guiding in leaving it east heavy east on the western side, some folk obviously will see a difference especially at lower altitudes

Obviously Home Position in Southern Hemisphere is mount set level with front tripod leg pointing towards SCP , altitude set to local latitude and counterweight shaft pointing down front tripod leg

Hope the above makes sense

Martin

[DarwinAstro]

Got it, thanks.