I want to get the ES24mm 82' eyepiece for my 6SE, but have to upgrade to a 2" diagonal. Is a SCT better than a push-on with SCT adapter? What brands are best for this scope in keeping the focal length the same?
Re: 2" diagonal for 6SE
#5364291 - 08/12/12 04:17 AM
1. A SCT threaded diagonal will give you a shorter optical path than a 2" visual back and a push-in diagonal, and that's very important on the 6SE ... the smaller SCTs are much more sensitive to aberrations caused by overextension of the backfocus distance & aperture reduction by baffle tube intrusion than larger models.
A shorter optical path still would result from using a low profile SCT to T thread adapter to mount a T threaded diagonal (smaller than 2", but considerably larger than 1.25") ... and using a 2" visual back on the output port of the diagonal. Modular T threaded accessories from Baader are good to excellent quality.
2. Bearing in mind the small size of the baffle tube in the 6" SCT, I have serious doubts that it would be cost effective to use a 2" fitting wide angle eyepiece with it. That baffle tube will seriously restrict actual field of view long before you get close to the edge of the field stop.