TheSkySearchers

Hi,

Today I attempted to collimate my new telescope. The result can be seen in the photo.

The primary mirror is perfectly within the FOV (all the adjusting clips are visible, and the secondary and vanes are bang on in the middle of the primary..

However, this whole "reflection" is not centered ON the actual mirror. (The photo doesn't do it justice, it's not that bad).

Is this an issue?

Thanks.

Looks like the secondary is too far up the tube and needs to be moved closer to the primary.
It may be missing some of the light cone otherwise.
Loosen the secondary central screw and wind in the three adjustment screws to bring it down further.

goldstar wrote: ↑Thu Jul 30, 2020 9:20 pm Looks like the secondary is too far up the tube and needs to be moved closer to the primary.
It may be missing some of the light cone otherwise.
Loosen the secondary central screw and wind in the three adjustment screws to bring it down further.

[mention]goldstar[/mention] Great, I see now. Is it a necessary fix though? I tested last night on the moon, which was nice and sharp, and Vega, which came to a point.

I just don't want to mess if I don't have to.

No it's normal, see https://www.catseyecollimation.com/pensack.pdf

SkyHiker wrote: ↑Fri Jul 31, 2020 12:06 pm No it's normal, see https://www.catseyecollimation.com/pensack.pdf

[mention]SkyHiker[/mention]
Reassuring...but what about the fact that I can see the optical tube through the collimation cap...I have a feeling this isn't natural?

If you can see the whole mirror, and more, from the centre of field, it means 100% illumination of the field at the centre. if there is an offset, you may get some asymmetric vignetting towards the field edge. If you're getting good results, use it for a while, look for vignetting and decide if you need to 'fix' it.