@@AstronomieRO20 ah yes I did realize later that you had removed the eyepiece. That how you shifted the back focus to so far back. You have effectively done a large crop factor to increase magnification. The vignette effect is to be expected with such a narrow tube.
are you holding your phone camera up to the eye piece?
No, the view is without eyepiece with only the camera on ISO 50 and out of focus mode.
@@AstronomieRO20 ah yes I did realize later that you had removed the eyepiece. That how you shifted the back focus to so far back. You have effectively done a large crop factor to increase magnification. The vignette effect is to be expected with such a narrow tube.