[madbadgalaxyman (Robert)]

Thank you, John, for a fine image. The impression I get is of good angular resolution.
A lot of the so-called "detail" seen in other images of NGC 253 seems to me to be more artefacts of processing instead of the actual structure of this galaxy. But this is not the case in your image....it does not have that "over processed" look which tends to falsify the real-world morphology of a galaxy.

The HII regions look quite small, which would tend to argue against this galaxy being of Hubble type Sc.

The visual wavelengths classification of this galaxy, using blue light images and according to the precepts of Alan Sandage and Gerard de Vaucouleurs, might be type Sc (with just the merest hint of a bar), but the near infrared classification of NGC 253 - a wavelength regime which leaves out most of this galaxy's heavy dust distribution - has been given in the literature as SBb (a strongly barred galaxy).

I would be very interested to see what your H-alpha channel looks like, as the larger HII regions should be good tracers of the spiral structure of this galaxy. Of course, the H-alpha bandpass will also include some light from the stars of this galaxy.

Interestingly, NGC 253 has much redder optical colours, overall, than most spiral galaxies....but this could just reflect the reddening of starlight by the heavy dust screen within this galaxy.