:: If it's so stubby then maybe the field of view is wider and they gave it more megapixels to compensate, due to a lower focal ratio . talk ) 19 : 09, 27 June 2012 ( UTC)
32.
The effect is proportional to the fourth power of the diameter and inversely proportional to the third power of the focal length, so it is much more pronounced at short focal ratios, i . e ., " fast " lenses.
33.
Unfortunately, the only large aperture wide-field telescopes before Schmidt were ordinary reflecting telescopes of short focal ratio ( about f / 3 ), and these presented images which while sharp at the middle of their fields of view, quickly lost their definition away from the field center.
34.
They are relatively short for their aperture . ( Because the light path is folded, the real focal ratio is slower than the length would suggest, i . e . slower than the f / 5 you estimate . )-- talk ) 00 : 36, 5 December 2007 ( UTC)
35.
Just for information, could you tell me wich telescope is the brighter ( for visual observation of galaxies, nebulae, clusters, . . . ) : a " Newton 200mm / 1000mm " ( focal ratio = 5 ) or a " Schmidt-Cassegrain 305mm / 3048mm ( focal ratio = 10 )?
36.
For example, a greater degree of barrel and pincushion distortion is tolerated in lenses that span the focal length range from wide angle to telephoto with a focal ratio of 10?or more than would be acceptable in a fixed focal length lens or a zoom lens with a lower ratio.
37.
Just for information, could you tell me wich telescope is the brighter ( for visual observation of galaxies, nebulae, clusters, . . . ) : a " Newton 200mm / 1000mm " ( focal ratio = 5 ) or a " Schmidt-Cassegrain 305mm / 3048mm ( focal ratio = 10 )?
38.
Because it was targeted at the novice market the telescope had its limitations : The general design was for low power hand-held or wide-angle work, the short f / 4 focal ratio did not allow for high magnification without the image degrading, and the primary mirror was factory aligned with no provisions for adjustment.
