collimating a Maksutov

Hello fellow Astromarters,

I'm new to maksutovs and I just recently purchased a cute little Pico Mak from Japan. As I was defocusing during a star test I noticed a vertical black line passing through the diffraction rings. (Illustration is attached) The black line moved sideways as I move the scope to the left and right. I don't think its effecting my optics but I'd like to know if anyone has experienced the same effect and can explain what the cause may be.

Thanks

Nat
PS I'm on Australian time.
Cheers

Attached Image:

If it's relatively sharp against the diffraction ring and convolves across it as you tease pointing --- I'm thinking the roof in a prism close to the image. Are you using a prism in front of the eyepiece? If so - that's it and would be benign/go away when you are AT best focus. You can also tell by just looking in without an eyepiece against a bright sky or wall. and you will see a skinny little line bisecting the field. Or look in thru the front of the scope for that line. Let us know! Tom Dey