darkairmouse

That was Vixen VMC200L with Apogee U8300. A Telescope-service filter drawer (with 2" Baader Ha) was put right in front of the U8300, no other adapters between the CCD and the drawer.

I don't even know what I'm seeing here - is that primary reflection in secondary? Or this shows incorrect distance between secondary and primary?  I did re-collimate all 3 components: focuser, secondary and the primary though.

Yue

Just to add here another evidence to show the possible microlens pattern with an ASI178MM..

I thought ASI178 doesn't have microlens..Doh!

And thank you for pointing 'microlensing' out to me! Just Googled, haha I can imagine you shake your head when you read my post - '...caused by microlensing...'  😝   

Thank you Mark!

Yue

Hi guys,

This is just a quick test shot - 5x240sec, Borg45EDII @325mm, no flattener; 1.25" Astronomik CLS CCD filter, ZWO ASI178MM-Cool.

Noticed that ugly reflection pattern around that bright star.

I had a similar thing before but that was a VMC200L and SBIG ST8300 (microlensing) with an IR pass filter, so microlensing was the one to blame.

Should I blame the Borg45EDII this time, or the filter? 

Thanks!

Yue