Quote:
Originally Posted by craigcullum
Hi,
Here's another f ratio question, I understand that a fast telescope produces a wide field of view in comparison to a slow one.
Because of this planetary viewing is better with a slower telescope due to it's limited field and greater magnification.
Why would you not buy a fast telescope, say f/4.5 and compensate with a high magnification eyepiece or a barlow lens?
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You are right in a way, but it isn't the most ideal. Using a barlow is adding another layer to the whole equation. The less layers and chances to lose light/contrast/colour the better. The same problem goes the other way too... if you have a long focal length scope (e.g. SCT) and you add a focal reducer it isn't quite as good as getting a shorter length scope.
No one scope is ideal for all things!