I have a 110mm reflector, however the mirror is not marked at the center, making it tough to use the tools I usually do to collimate.
What is the best way to find the exact center?
Posted 13 August 2019 - 07:53 PM
I have a 110mm reflector, however the mirror is not marked at the center, making it tough to use the tools I usually do to collimate.
What is the best way to find the exact center?
Posted 13 August 2019 - 08:27 PM
Just like finding the center of a circle, only you have a glass circle.
Rather than explaining here... I will suggest a lesson in geometry, or you tube or a Google search.
Once found you can mark it with a water based marker, or a simple stick on dot.
Posted 13 August 2019 - 10:17 PM
I suppose so.
The mirror is in it's cell and I don't intend to remove it. This complicates things.
I also can't use a pencil to draw lines, nor can I use a compass.
So, rather than a geometry lesson, I just need some practical suggestions as to how to go about it.
Posted 13 August 2019 - 10:18 PM
I have a 110mm reflector, however the mirror is not marked at the center, making it tough to use the tools I usually do to collimate.
What is the best way to find the exact center?
Take a square piece of paper, fold it in half first in one direction then at 90ยบ, make a pinhole where the creases cross. Measure 55mm along each crease and make a pencil mark.
Line up the piece over the mirror so the 4 marks match mirror edges and using a marker pen make a mark where the pinhole is...
Be careful not to slide the paper along the mirror surface ...
Posted 14 August 2019 - 03:19 AM
So so practical.
Thank you for your discerning reply.
Posted 14 August 2019 - 09:22 AM
I have a 110mm reflector, however the mirror is not marked at the center, making it tough to use the tools I usually do to collimate.
What is the best way to find the exact center?
Find the middle.
Pete
Posted 14 August 2019 - 09:27 AM
Now that you know how to mark the center, what's the focal length of the mirror?
Posted 14 August 2019 - 09:29 AM
What's the focal ratio? If it your new Tal 1, it may be slow enough that the mirror is spherical and placement of the center spot is not critical.
Jon
Posted 17 August 2019 - 08:34 AM
Reporting back - used the square paper method and it was fantastic - so easy.
Added a center spot, collimated wonderfully - very happy.
Amazing Jupiter, Saturn and the moon tonight.
Thanks Kunama! Your a legend.
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