Editing Optical telescope (section)

====Optimum====
The following are [[rule of thumb|rules-of-thumb]] for useful magnifications appropriate to different type objects:
* For small objects with low surface brightness (such as [[galaxies]]), use a moderate magnification.
* For small objects with moderate surface brightness (such as [[planetary nebulae]]), use a high magnification.
* For small objects with high surface brightness (such as [[planet]]s), use the highest magnification that the current night's "seeing" will allow, and consider adding in [[astronomical filter]]s to sharpen the image.
* For large objects (such as the [[Andromeda Galaxy]] or wide-field [[diffuse nebulae]]), regardless of surface brightness use low magnification, often in the range of minimum magnification.
* For very to extremely bright, large objects (the [[Moon]] and the [[Sun]]) narrow-down the aperture of the telescope by covering it with a piece of cardboard with a small hole in it, and insert filters as-needed to both cut down excess brightness and to enhance the contrast of surface features.

Only personal experience determines the best optimum magnifications for objects, relying on observational skills and seeing conditions, and the status of the pupil of observer's eye at the moment (e.g. a lower magnification may be required if there is enough moonlight to prevent complete dark adaption).