Is there any significant (for either visual or photographic use) difference in light-gathering ability between the 10" Mewlon 250 and the 11" Celestron C-11?
The C-11 with its central obstruction of 34% and XLT coatings (average 400-750nm transmission of 83.5%) should give the equivalent of a perfect 9.45" diameter scope.
11 * sqrt((1-.34^2)*.835) = 9.45
The M250 has a smaller mirror, relatively smaller (29%) central obstruction, no corrector plate, and different mirror coatings. Does anyone know how it compares in light througput? I'm looking for a quantitative answer, if possible.
I'm sure that there are many other considerations, such as optical and product quality, price/performance, and f-ratios, but I'd like to keep this discussion limited to the physics of light throughput.
Thanks,
Allen
The C-11 with its central obstruction of 34% and XLT coatings (average 400-750nm transmission of 83.5%) should give the equivalent of a perfect 9.45" diameter scope.
11 * sqrt((1-.34^2)*.835) = 9.45
The M250 has a smaller mirror, relatively smaller (29%) central obstruction, no corrector plate, and different mirror coatings. Does anyone know how it compares in light througput? I'm looking for a quantitative answer, if possible.
I'm sure that there are many other considerations, such as optical and product quality, price/performance, and f-ratios, but I'd like to keep this discussion limited to the physics of light throughput.
Thanks,
Allen