Now this is why I bought a refractor! Star bloat has always caused me issues when imaging M45. I've always used reflectors and found it very difficult to control star bloat on this target. The image below is an urban shot with a waxing gibbous Moon about 50 degrees away. To see a comparison with a reflector image click here.
Object M45  Object RA 03:47:00 Dec 24:06:55
Date 15 December 2018
Exposure 40 minutes (20 X 2 minutes) 
ISO 800
Camera Canon 60Da DSLR
Optics Prime focus of an Esprit 120 f/7 APO refractor with a focal length of 840 mm
Location Bedford, Nova Scotia
Processing This image was processed entirely in Images Plus. Calibration, stacking, statistical filter applied to reduce noise before stretching. Masked stretching and split star processing used to enhance the image. Masked noise reduction using a frequency domain lowpass filter applied to the DSO layer and then it was recombined with the star layer. Image binned 2 by 2. Final sharpening applied. Since the 60Da has on sensor dark suppression no darks were used in the calibration.