Advice on photo

[DDH]

Hello, I have been trying my DSLR on both my telescopes and after a session I noticed something unusual on a set of shots, the objective was the Pleiades group and in all the photos of the session there is 1 bright star close to the bottom right  that has what I have been told could be lens flare.  What I would like to know, is it possible to get lens flare with the camera connected to a telescope.  I do know that it is not unusual with the normal lens on the camera as they usually have a set of lenses in a group.  The photos were taken using a Skywatcher skymax 127 maksutov with a Canon EOS6D mk2 directly connected to the scope using only a 1.25 nose piece into an Omegon T2 ring.  There was 4 frames taken over 3 minutes at ISO 6400 15 seconds exposure and all appeared the same, no other stars in the photo exhibit the same issue.  A previous session using exactly the same settings showed nothing unusual.  What is the expert verdict?

Edited January 28, 2022 by DDH
glitch in layout

[happy-kat]

Do you use a dew shield, or was there an outside light light on, or was the Moon around. 

[ONIKKINEN]

Could be an internal reflection of some sort, but a more pressing issue would be focus. Zoom in and you see stars have hollow and dark cores which means you were out of focus when imaging, so best to fix that first.

[vlaiv]

Not sure if I'm an expert, but verdict is this:

1. Your focus is off.

2. Your collimation is off - but that might be focuser tilt as camera could be too heavy for 1.25" attachment with compression ring (it is better to just use T2 ring and screw camera onto the scope).

3. You are over sampled and you should really look into binning

4. There is definitively something causing flaring in bottom right corner - it is not only one star that is affected - but multiple stars

there is faint flare next to one of the stars, and there is flare of the star that is outside of the FOV - but flare is inside:

I'm really not sure what could be causing these.

The one thing I can tell you - it is not because front corrector plate or secondary mirror. It needs to be inside optical path, near the focus plane of the telescope as it affects only one side of the image (not all stars).

My guess is that you have internal reflections from that 1.25" nose piece. Hold it against light and see if internal side is shiny (or has some sort of grooves and is colored black - this second thing is good, rest is bad).