[Robh (Rob)]

Hi Matt,

Your 14 inch (~360mm) Skywatcher should be a great scope. From its specs, I see it has a 1600mm focal length.
Your 25mm EP gives a magnification of 1600/25=64 and an exit pupil of 360/64=5.6mm.
The 42mm EP gives a magnification of 1600/42=38 and an exit pupil of 360/38=9.5mm.
Your night-time eye pupil size is probably about 6mm but it could be much lower or slightly higher. This means your 42mm EP is losing a lot of light and contrast as 9.5-6=3.5mm of exit pupil diameter is not entering your eye.

The longest focal length EP to gain maximum light and contrast for your scope is 6x1600/360=27mm. So your 25mm is pretty close to ideal. Keep in mind that this assumes your pupil size is 6mm.

To get a bigger field of view, you need a near to 27mm EP with a larger apparent field of view, which will still preserve the exit pupil size.

To get a better view of NGC 253, you need darker skies. Wait until you get a moonless night. Your view of the galaxy will be better when it is in the western sky away from the brighter eastern Sydney skies. If you can get to a darker viewing sight out of the suburbs, it will be better again.

Regards, Rob