Hello all, this is my first post.
I am new to this. I have acquired an orion XT8 with two 1.25" EPs (10mm, 25mm). The first thing I would like to invest in would be a decent 2" eyepiece. I have been doing some reading and it appears that a Q70 / Agena SWA 32 mm would seem like a good choice. The price also seems reasonable; I am not quite ready for multi-hundred dollars EPs yet. Would you agree with this pick? What else would you recommend in that focal length vicinity and price range (I am flexible).
Also, if you think you have something for sale you think I might be interested in, obviously I am interested to hear about it since I cannot post in the classified section for 30 days!
The 32mm focal length is as long as you would want to go, because with longer focal-length eyepieces (such as the 38mm and 40mm available on the market) will cause the secondary mirror shadow of your telescope to appear visible --and you'll want to avoid this.
Also: I would suggest avoiding the Agena SWA or SWAN eyepieces you are looking at, or similar 5-element 70-degree eyepieces because I know for a fact that a considerable portion the outer field will be *strongly* astigmatic/distorted in an f/6 telescope.
With all due respect to other's expressed opinions, I personally own the related 5-element SWAN 40mm, and even in my f/7 refractor the outer field has a lot of aberration.
These Agena and William Optics SWA/SWAN and similar 5-element type 70-degreeish eyepieces are derivative of the classic Erfle design, and really only produce clean outer fields in telescopes of f/10 and slower.
For $230 or less you can get the 30mm APM Ultra Flat Field which produces 70-degrees AFOV and will be extremely clean across the field of view even in your f/6 scope. this is one of the very best eyepieces on the market today in that AFOV range. Clones of this APM 30mm are offered by other manufacturers for less than $200, and they should be good also.
Below linked is a very affordable alternative made in USA 32mm 2-inch 60-degree AFOV Plossl type eyepiece which should produce a *much* better-corrected field in your f/6 scope that the Erfle-derived SWA series you are contemplating.
FYI: Don't let the unorthodox nature or low price of Gary Russell's eyepieces scare you. Gary Russell has been building unique eyepieces for a few decades now, and is well known in the astronomical community. He obtains high-quality surplus lens sets, and machines his own Delrin eyepiece bodies/barrels.
But seriously, again, the SWA you mention, and similar Erfle-derived 5-element eyepieces will aberrate pretty badly in the outer field at f/6.
Edited by Thomas_M44, 01 December 2020 - 08:30 PM.