This image is about 1 deg wide - and M46 seems quite lost in the starfield.
In the cluster you can see the PLN NGC 2438 in the middle and PLN 231+ 4.1 at the Right of the image (A small red circle)

please see next image for a closeup on NGC 2438 see next image...

This image was shut with 2 telescopes:
The wide field image was shut with 16" Dream scope F3.75 from Tivoli farm in Namibia for 40 min (LRGB 10 min each...)
The shells toook another 12 hrs of Hydrogen Alpha to be visible.
In addition the shells were enhanced further in Ha with a 12" F7.5 LX200 from Israel.

Total imaging time 13 HRS with the 16" Dream scope.
And 10 Hrs with the 12" scope
Grand total of 23 HRS.

Imaged May-December 2015