3 replies to this topic

[Whereisclearsky]

Hi,

 

I have a Cheshire Collimation Eyepiece with Steel Wire Crosshairs.

The scope is ES 16” Dobsonian.

 

Previously my scope had crosshair like spider vanes but this time

its not the case.

 

So I am a little bit confused how do I align everything?

 

This is with cheshire in but it’s really hard to photograph.

https://imgur.io/tB4vTVZ?r

[Bill Weir]

An image of the secondary holder would be nice. What does the support structure look like?

 

Bill

[Whereisclearsky]

An image of the secondary holder would be nice. What does the support structure look like?

 

Bill

https://i.imgur.com/lkRBFXq.jpg

Edited by Whereisclearsky, 27 September 2023 - 10:32 AM.

[Starman1]

Hi,

 

I have a Cheshire Collimation Eyepiece with Steel Wire Crosshairs.

The scope is ES 16” Dobsonian.

 

Previously my scope had crosshair like spider vanes but this time

its not the case.

 

So I am a little bit confused how do I align everything?

 

This is with cheshire in but it’s really hard to photograph.

https://imgur.io/tB4vTVZ?r

Secondary spider vanes are not involved with collimation.  Spider vane type is irrelevant.

Collimation is:

1) moving the secondary until it is centered under the focuser.  Your Sight Tube/Cheshire will work for this.  If you have to it is quite permissible to angle the focuser using its tilt screws to accomplish this.

2) Aligning the focuser axis to point at the center of the primary mirror by adjusting secondary mirror tilt.  Your Sight Tube/Cheshire will work for this, using the crosshairs.

3) Aligning the optical axis of the primary to point directly back to the crosshair crossing.  This is done with the Cheshire part of your tool by centering the primary mirror center marker in the center dark area in the Cheshire.

 

Here is an illustrated Tutorial involving the same kind of tool you use, only with the images separated for clarity:

https://catseyecolli...com/pensack.pdf

 

I also have an illustrated tutorial for the use of your type of tool without the images separated, but it's too big to post here.

Send me your email in a PM, and I'll send it to you.

Don

Edited by Starman1, 30 September 2023 - 05:50 PM.