thanks for the reply.
I'm definitely going to get the ethos and will order one for bintels next lot.
I think the ethos 13mm with it's very wide FOV should remove the need to get anything in the 10-17mm range at least for now.
The 6mm radian vs the 7mm nagler t6 is a bit more interesting though.
I don't wear glasses and am not real fussed about eye relief.
Regarding this don @ bintel wrote this ;
Quote:
Looking at the numbers I came to the following conclusion.
For lunar and Planetary observing a large field of view is not always necessary. In fact a larger FOV will give a smaller scale to the planets.
The Focal length of the 16" Lightbridge is 1829mm f/4.5
Using a 6mm Radian it would give you 304.8x and yield a 11.8' FOV. Jupiter fits 16x and Saturn fits 29x. A good scale size.
Using a 7mm Nagler it would give you 261.2x and yield a 18.83' FOV. Jupiter fits 26.9x and Saturn fits 45.8x. A smaller scale.
With this in mind I would be leaning more towards the 6mm Radian. With the 20mm of eye relief this is comfort all the way for planetary viewing.
|
So with that in mind the 6mm sounds the go however I a just a little concerned that the radian at 300x will be pushing it a bit (conditions wise) and also at 300x with a narrower FOV stuff will fly out of the eyepiece very quickly and will need constant 'tapping'