This sense of immersion matters a lot to some people, including me. Somehow I've never seen the 50mm UVs, and should try them. I'll also keep it in mind next time I have a chance to try the NV. My own general impression is that the more manufacturers increase ER for spectacle wearers -- we're up to 20mm now, how much could be considered enough? -- the less AFOV there seems to be to enjoy, and the more often I find eyecup depth inadequate. (Is this what Peter meant by blackouts?) Field flatteners also seem to decrease AFOV, independently, so AFOV is taking a double hit lately. (Technical corrections or explanations welcome here.)
Tenex,
Interesting observations.
I went through a list of binoculars, where I can see the entire field with my glasses on, and checked their afov using this online calculator:
https://astronomy.tools/calculators/binoculars
I used the ISO standard method.
As might be expected, the LESS IMMERSIVE ones have a smaller AFOV:
Vanguard Endeavor ED II 8x42 53.31° AFOV
Zeiss Conquest HD 8x42 54°
Leica Ultravid BR 7x42 52°
Leica Trinovid HD 8x32 52.6
in other words, more of a 'pipe' style of view, however beguiling it might be.
The MOST IMMERSIVE ones have the largest AFOV:
Swaro EL WB 8x32 58.6
Leica Noctivid 10x42 58
Zeiss Victory SF 8x42 61
Eye relief on these vary between 17 (Trinovid HD) to 20 (Swaro EL)
The correlation between eye relief and its impact on FOV isn't quite
apparent to me yet, as one of the wider true fields (8x32 Swaro) also has the most eye relief. Also the Victory SF has the widest true field, a flat field, and the widest AFOV of all the ones listed, plus 18mm of ER..
Perceptually 'narrow' AFOV, for me, lies below 54°, and immersive is
happening at 58° and beyond.
Granted, immersion is another subjective impression, characterized by me as the widest possible view I can see, where the field stop is still visible, yet it is close to the periphery of my vision.
So, I'm not convinced that long eye relief is necessarily to blame for impacting true field or apparent field of view, at least within the range of binoculars I listed. It may require more complex, and heavier, eye piece designs though.
-Bill