Quote:
Originally Posted by Valmir
Would a scope with a focal length of 1900mm make the horsehead nebula visible?.
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what you can see depends mostly on the aperture (size of the main mirror/lens, which for your telescope is 114mm) of a telescope.
a bigger main mirror/lens is the most important feature of a scope when you want to see dim objects.
a bigger mirror means more surface area, more surface area means more light can be collected, and with more light dimmer objects can be seen.
thats why the size of a scope is ALWAYS measured by the size of the main mirror: it tells you more about what a scope can see then any other number.
i noticed you're asking about the meade ETX scope's, so i assume that thats the scope you're referring too. in that case then no, the ETX's are way too small to see the horsehead.
sure, they have long focal lengths, but what matters is aperture. the largest ETX only has a 125mm wide main mirror, which is far too small to see the horsehead. to get even a glimpse of the horsehead you need a far bigger scope.
Jarrod