Moving across the eyepeice

[Jedite83]

For Christmas my father-in-law gave me his old 4" Newtonian and i must say its a huge improvement over my binoculars.

The last 2 nights i pointed it at Jupiter and discovered when using the higher power eye pieces the image was harder to focus and moved across the eyepiece rapidly (with the highest power it took less then 2 minutes to move across the FOV). Is this normal or something I need to address?

[Steve Ward]

How is the 'scope mounted ... ?

If it is a non-tracking mount such as a dobsonian then the object will very soon move through the field of view .

If it is a tracking equatorial mount then you need to polar-align it first .

[Moonshane]

The reason for the movement across the eyepiece is that the Earth rotates and is the reason all things 'move across the sky'. The moon is more complex as this also orbits the Earth in the opposite direction, moving a little more 'east' each night.

[Uplooker]

the image was harder to focus

This is becasue the image is affected by the "seeing". Similar to a heat haze on a hot day. The atmosphere is "boiling" and disrupts the view. Best to get the best focus you can and leave it! You will will have moments of good views and poor views as the seeing improves or degrades.

Ian

[Jedite83]

How is the 'scope mounted ... ?

If it is a non-tracking mount such as a dobsonian then the object will very soon move through the field of view .

If it is a tracking equatorial mount then you need to polar-align it first .

It is a non motorized Altazimuth mount.

[ghostdance]

It is a non motorized Altazimuth mount.

Welcome to the Ancient Order of Nudgers!

Fear not, assuming your altaz mount has a nice smooth action, the gentle art of nudging the scope need not be too frustrating. Try putting Jupiter at one side of your eyepiece so it travels across your field of view then follow it as smoothly as you can. It gets easier with practice!

[Dave In Vermont]

The reason for the movement across the eyepiece is that the Earth rotates and is the reason all things 'move across the sky'. The moon is more complex as this also orbits the Earth in the opposite direction, moving a little more 'east' each night.

So the magnification you use with your scope is not only giving you a closer view of the object you're viewing, it also magnifying the Earth's rotation by the same factor. 100X and the Earth's rotation is 100X faster. This also magnifies any problems with the 'seeing' at the time. High altitude atmospheric disturbances are thereby also made 100X greater to the Earth-bound observer.

Clear & Still Skies,

Dave

[Bart]

,

I know what you mean!

[emoji1]

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