[Ryderscope (Rodney)]

I have an artifact on my Red filter subs that has appeared with my current image project (M45 - Pleiades). See attached jpeg of a red sub along with a crop of the corner where the artifact can be seen. Lens was my EOS 200mm prime and camera the QSI683-ws8.

The artifact was not there on the subs from my previous image project (Fornax galaxies). The lens has been removed and replaced since my last image and I made sure to use a hand puffer to blow out any dust before replacing the lens.

I took a set of flat frames prior to starting the image capture for this project and a copy of the same corner on the Red sub flat is also attached to this post. As you can see there is no apparent artifact on the flat frame.

So before I go and start pulling my filter wheel apart I was wondering what the consensus would be as to whether this is some rubbish that has found its way into the filter wheel or if it might just be some sort of reflection phenomenon.

The images as they appear below from left to right are:
- One of the Red subs
- A crop of the bottom left corner of the Red sub
- A crop of the bottom left corner of one of the Red flat frames

Subs exposure time = 300s

Thought of others on this would help.

Thanks for looking.

Rodney.