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With a 5mm focal length the difference between ~70 deg AFOV eyepieces and ~80 deg AFOV eyepieces is fairly marginal IMO. I find it a lot less noticeable than I do with longer focal length eyepieces operating at lower powers where the TFOV is more important.
With a 5mm eyepiece provided the AFOV is > ~ 65 deg, the most important factors IMO, are comfort, contrast, sharpness and light throughput.
There are several excellent eyepieces around this focal length. My personal favourite is the 5mm Pentax XW. The Delos and Baader Morpheus are also excellent. If your budget conscious a 2nd hand 5mm TV Radian is also a good choice, if you can find one. While many will disagree, I don't rate the 5mm Nagler T6 quite the equal of the Pentax XW's or TV Delos in terms of the 4 criteria that I consider most important, although it is still a very good eyepiece if you're happy with the eye relief.
Cheers
John B
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