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Really thats the only reason for the 2" barrel - it allows a larger true field of view(TFOV). A 1.25" eyepiece resticts the TFOV to about 1.3 degrees compared with a just over 2 degrees with a 2" eyepiece.
For plossls apparent field of view(AFOV) about 50 degrees) in my 10" f5 dob the largest eyepiece in 1.25" would be 32mm, for a "super wide" (about 68 degrees) it is about 24mm, an "ultra wide" (about 80 degrees) it is about 20mm, an ethos about 16mm.
regards
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