Squaring A Focuser (with photos)

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Squaring A Focuser (with photos)

Postby Dion » Mon Sep 20, 2010 11:36 am

I have just flocked my scope, meaning everything is off it, i just have a metal tube currently flocked, therefore a couple of things 'may' look different but only because I'm rebuilding while writing this. There are arguments for an against precise focuser centering but after reading a fair amount of information and also working with the collimating by video camera thread with doc, I am 100% convinced that a centered focuser produces better collimation.

Tools You Will Need

Either a vernier gauge or a good steel rule
pencil
Screwdrivers to remove focuser
a laser collimater OR cheshire
a strip of thin card

The thin card size varies depending on scope diameter, but for a 200p a 1" wide strip cut from the long side of an A4 will do.


Firstly, remove the focuser AND your secondary mirror and measure the diameter of your tubes focuser hole, you must do this with the steel rule/vernier ALONG the axis of the scope, not across it, a round hole in a curved surface measures smaller if you measure along the axis of the curve.

Take the measurement and half it, mine measures 95mm so halved is 47.5mm. Write the figure down

Next, measure the distance between the edge of your hole and the edge of your scope, bear in mind on my photos, the end trim isn't fitted due to flocking, you dont need to remove yours but then obviously you measure to the very front INCLUDING front trim. Mine came to 41.5mm

Add this figure to the one you wrote down, so, 41.5 + 47.5 = 89.

This gives the distance from front of scope to center of focuser hole.

Image

Image

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Re: Squaring A Focuser (with photos)

Postby Dion » Mon Sep 20, 2010 11:37 am

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Re: Squaring A Focuser (with photos)

Postby Dion » Mon Sep 20, 2010 11:38 am

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Re: Squaring A Focuser (with photos)

Postby Dion » Mon Sep 20, 2010 11:40 am

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Re: Squaring A Focuser (with photos)

Postby Dion » Thu Dec 30, 2010 12:54 pm

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