Quote:
Originally Posted by glend
Colin, thanks, i would probably prefer an f5, simply for ease of collimation and longer focal length of 1000mm. The concerns i have with newts (in their pure form) are: diffraction spikes, the mandatory secondary heater, focuser/camera positioning, but i lived with those issues with my 10" f5 newt. The good thing about newt choice is that i can get carbon tubes for most of the popular imaging versions, which might allow greater aperture for the weight limit. I already have a Baader MPCC and spacers for my camera.
|
You've just named every single reason why I went with a refractor over a newt or a MN190
Not a fan of diffraction spikes and I don't like the focuser position.
I tend to agree with Suavi, the closer you are to 500mm the better. At 400-800mm you are at a nice pixel scale where you can drizzle every bit of good seeing out of your data but not be as restricted on nights of less than perfect seeing.
As you say however Glenn, F/5 is a LOT easier to deal with in the way of collimation and sensor orthogonality.