Aperture is King - but not always...
Light pollution is the arch enemy of Faint Fuzzies. While there are a lot of nebulae that can still be seen under urban skies, galaxies are a different matter.
The best place to view galaxies is from a dark site.
Then, to be able to make out details such as the spiral arms, the bigger the aperture the better. Even those galaxies whose arms are easiest to identify, really a 12"scope is just about the smallest aperture. The one exception is M31, the Andromeda galaxy, whose dusty lane and arm structure is visible in binoculars from a dark site under transparent skies, and even NGC 253, the Silver Dollar galaxy shows this dusty lane structure.
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If you have access to a 12" or larger scope, again the larger the aperture the fainter and finer detail that can be seen within the arms.
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Apart from arms, the main details visible are the core and soft halo of the main body. There are a few galaxies that reveal dark, dusty lanes, and fortunately scopes as small as 4" can show these stark, intricate and lovely details. M104 the Sombrero galaxy, NGC 4565 the Needle galaxy & NGC 5128 the Hamburger galaxy, are all edge on galaxies that show a dark lane that can be seen through smaller apertures.
There's another type of galaxy that shows another set of details. These are very active galaxies which as a result have their neat spiral structure disrupted. As a result they show a mottled, spotty structure.
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One other galaxy type is highly disrupted due to a recent close encounter with another galaxy, and the resulting gravitational tidal pull between the two bodies caused the galaxies to become very distorted. The Hamburger is also one such faint fuzzy. Some galaxies are also in the middle of this gravitational interplay, even merging process. The Antenna galaxy is a pair of such interacting, highly gravitationally distorted galaxies.
Trick with small apertures
Smaller apertures, say 8" and smaller, have a trick up their sleeve - low magnification.
By dropping the magnification, the image become more concentrated, and hence intensify the image of those faint fuzzies in order to help spot them.
Details may be possible to make out, like the core and halo, but many galaxies, such as ellipticals, only glow as small round glows, nebula like.
Binoculars, especially 70mm and larger, are also very good in galaxy hunting. These are small aperture, low magnificaiton refractors, and the edge they have is the brain is so powerful that in combining the image from both eyes, a single image is produced that is brighter than that of a single refractor of the same aperture size.
Alex.