Telescope used was a Meade 6″ Schmidt Newton with a Sony A6000a attached.
The telescope was mounted on a iOptron CEM25P mount. No guiding.
6x 60sec ISO3200.
The photos were stacked manually using Photoshop CC. Then adjusted to taste in Lightroom CC.
The image is oriented with north down and east right.
Coma diameter 8.8 arc minutes
Tail 1.3 degrees PA 275 degrees, tail may extend beyond the field of view.
On 2018-September-14, Charles Morris, an experienced comet observer estimated comet 21P was about visual magnitude 7.3 with a diameter of 7 arc minutes using 20×80 binoculars. Others estimated tail length at least 1.8 degrees. (Foto door Rutger Bus)