Quote:
Originally Posted by skysurfer
This does not cut down imaging time. Only a larger aperture in mm cuts down image time to get the same faint objects.
But, indeed a triplet wins over a doublet if you are a real pixel peeper. Otherwise, rather get a 100...120mm ED doublet plus reducer.
|
F5 is indeed quicker but yes aperture is the key. F5 means a wider swath of the field ends up on the same real estate of the sensor. So its collecting more total light.
I think also you'll find that more of the light that enters the lens actually lands on the sensor rather than only a large slice of it with a substantial amount missing the sides of the sensor.
Greg.