Secondary mirror centering - Newtonian

[moriniboy]

There are a few posts advocating the use of a ruler to make sure that the secondary mirror support is excatly in the centre of the ota.

I myself have always found this difficult as the ota is curved and the three adjusters invariably get in the way.

To make things easier I have started to used a kebab type skewer marked with a pencil line approximately where the secondary support is.

The trick is to get the gap between the pencil line and the support exactly the same for all vanes and bingo its done.

See attached photo as an example.

[Ad Astra]

Looks like an excellent, inexpensive DIY tip.

Well done!

Dan

[blinky]

Excellent idea! Might give that a try (Although I heard that fast F4 Newts sometime have the secondary offset???)

[Stephen]

Excellent idea! Might give that a try (Although I heard that fast F4 Newts sometime have the secondary offset???)

I thought I read the offset was built into the secondary holder, not the spider centre?

[blinky]

I dont know TBH! I just heard the words offset!

[umadog]

On some scope the offset is in the spider and on others it is in the secondary mount itself. On my f/4 it seems to be in the spider. The secondary post is centred in the tube in the direction parallel to the focal plane but offset in the perpendicular direction.

[Starlight 1]

Or you can do it this way - get a square piece of paper, mark the lid of the telescope onto the piece of paper, fold it in 4, snip the corner off, open it out, line your pencil mark up with the outside of the tube and the screw must be in the middle.

[blinky]

I just did it with the bamboo stick and it worked a treat! Great idea!!!!

[The Viper]

exellent idea i have been getting the same problem as u now where does the wife keep the skewers again