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Getting rid of the meridian flip.


Guest peepshow
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Guest peepshow

Just another daft (?) thought.


 


Normally the scope is slightly weighted to the east to prevent backlash, then a meridian flip is done at the meridian.


 


To avoid having to do any flip............


 


Adjust scope so that it is exactly in balance.


Then say, for the sake of insanity ( :D) that there was a small pulley on the angled RA axis and another nearby but vertical. 


The inner core of a Bowden cable is run around the first pulley then over the second onto a heavy suspended weight.  In this way the scope would always be slightly loaded in the same direction no matter where it was pointing.....so no meridian flip required.

Edited by peepshow
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Just another daft (?) thought.

 

Normally the scope is slightly weighted to the east to prevent backlash, then a meridian flip is done at the meridian.

 

To avoid having to do any flip............

 

Adjust scope so that it is exactly in balance.

Then say, for the sake of insanity ( :D) that there was a small pulley on the angled RA axis and another nearby but vertical. 

The inner core of a Bowden cable is run around the first pulley then over the second onto a heavy suspended weight.  In this way the scope would always be slightly loaded in the same direction no matter where it was pointing.....so no meridian flip required.

 

The flip is done to stop the scope hitting the tripod or Pier when using an GEM mount.

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Guest sharpie78

If I were to disable limts in EQ Ascom will my HEQ5 carry on tracking through the meridian while I'm imaging ? I was imaging M31 last night and ruined 5 subs cos I was busy doinng something else and forgot to re-slew it round when it got to the meridian limit. I suppose allowing it to slew through the meridian then raises the question....would I need to recalibrate the guiding software once it got to the west side of the meridian ?


If it were clear tonight I'd just try it and see but if someone already knows the answer.....bonus. :)


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If I were to disable limts in EQ Ascom will my HEQ5 carry on tracking through the meridian while I'm imaging ? I was imaging M31 last night and ruined 5 subs cos I was busy doinng something else and forgot to re-slew it round when it got to the meridian limit. I suppose allowing it to slew through the meridian then raises the question....would I need to recalibrate the guiding software once it got to the west side of the meridian ?

If it were clear tonight I'd just try it and see but if someone already knows the answer.....bonus. :)

 

If you disable the limits it will just keep on going.

The guiding will not be affected as the guide star position will still be the same relative to your target.

The danger lies in my last re the scope colliding with the tripod / pier if you forget about it, fall asleep or generally get sidetracked.

You may also end up pulling a cable out.

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Guest sharpie78

I've got good clearance all around my pier and I've made sure all my cables are long enough for the mount to rotate almost 360 degrees before they go tight. It's handy to know I can just disable the limits for those times when I get started half an hour or so before my target is about to cross the meridian. Thanks Graham. :D


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i turn off my limits, as long as you remember and keep an eye on the camera or scope hitting the mount or pier.


rough rule of thump, if you use you fist as a guide, put it between the mount or pier and the camera, a fist width gives you about an hour, two fists about two hours. 


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Guest sharpie78

good tip. I'm usually on the ball when I'm imaging but I got caught up doing some processing and reading chris hadfields book the other night. It's a good read but now I wanna be an astronaut.


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If when i start the target is close to the meridian i switch off the limits and manually slew the scope back to the target from the west side of the pier.

This way there is never going to be an issue and i can if needed just go to bed and leave it to get on with it. :rolleyes:

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If the camera does touch the mount then instantly the stars in your next sub have long trails so if you check each sub as it comes in like I do now you know something is wrong.


 


I've done it twice in the past, when you go outside the mount will be making a clunking sound every second or so, I guess as something in the mechanism slips. Hasn't done any permanent damage to my mount yet, touch wood.

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