The image attached is the original re-scaled by a factor of 2.
The field flattener I use is also a focal reducer X.8, So if I removed it mi picrures would ne that much bigger and if I keep the object in the ventr of the field of view the coma should not be too bad as Crab is not large
Apparent dimensions (V): 420″ × 290″
The flattener might be taken out for next years effort (the frames were gathered at elevation 30 to 33 degrees).
Chris