Collimation F5 Newton

[tarotrocola]

Hi,

considering the offset of the secondary in an F/5 newton, if you want to do a proper star test, do you need to make some cardboard mask centered in the tube and bigger than the secondary, so the offset of the secondary shadow doesn't affect the airy rings?

Regards,

Ivan.

[Moonshane]

No. The offset is irrelevant to collimation. You centre the secondary in the tube, the focuser drawtube and then align with the primary as normal.

[tarotrocola]

Ok, thanks! 

[denis0007dl]

For setting offset in most precise position, Catseye collimation tools are best!

[tarotrocola]

For setting offset in most precise position, Catseye collimation tools are best!

Interesting... I'll check that out.

[Jason D]

Hi,

considering the offset of the secondary in an F/5 newton, if you want to do a proper star test, do you need to make some cardboard mask centered in the tube and bigger than the secondary, so the offset of the secondary shadow doesn't affect the airy rings?

Regards,

Ivan.

I do not know if you came up with the "mask"  idea or read it somewhere. Either case, it is an improper idea that serves no purpose. Secondary offset does not effect star collimation when the latter is done properly. Star testing is conducted at high magnification with a slight defocus. If you see the spider vanes diffraction and the secondary offset clearly then you have defocused too much.

Jason

[tarotrocola]

I do not know if you came up with the "mask"  idea or read it somewhere. Either case, it is an improper idea that serves no purpose. Secondary offset does not effect star collimation when the latter is done properly. Star testing is conducted at high magnification with a slight defocus. If you see the spider vanes diffraction and the secondary offset clearly then you have defocused too much.

Jason

I've read it somewhere, and for me It doesn't make sense, but I wanted to be sure.