Noctivid AFOV (1 Viewer)

I just had the possibility to use two Noctivids in 8x and 10x side by side over the whole weekend. To my eyes, the 10x seemed to have a larger apparent field of view than the 8x. I expected it to be the other way around. Can someone who owns both formats confirm this observation? In general, the view of the 10x version appeared even a little more “immersive” to me, which I thought was unusual.

It is normal for any 10x binocular to have a larger AFOV than the equivalent 8x.
This is because the focal length of the 10x eyepiece is shorter than the 8x.

Say 50mm objective 200mm focal length.
10x eyepiece 20mm fl.
8x eyepiece 25mm fl.

The 10x (and 12x) eyepieces often have one or two more elements in a more complex eyepiece than the simpler 8x.
This gives a larger AFOV.

The prisms etc. forward of the eyepieces are usually the same in 8x, 10x and 12x.
With some makers I assume that the higher magnification prisms may be selected as more accurate than the 8x.
Possibly even better objectives.

B.

Lightbender said:

I just had the possibility to use two Noctivids in 8x and 10x side by side over the whole weekend. To my eyes, the 10x seemed to have a larger apparent field of view than the 8x. I expected it to be the other way around. Can someone who owns both formats confirm this observation? In general, the view of the 10x version appeared even a little more “immersive” to me, which I thought was unusual.

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There are different ways to calculate or measure AFOV but the common one involves multiplying by the magnification so one can expect that often the higher magnification will have the bigger AFOV.

It is usual for an 8x to have a wider actual fov than a 10x and perhaps this is what you were thinking of. The AFOV is not always a good guide as to how much of the world you see through the binos. Take a look at the fov in metres at 1,000 metres of Zeiss SF 8x42 and 10x42 and the 8x is much bigger but Zeiss states that the AFOV for both is exactly the same.

Lee

Thank you Binastro and Troubador for your explanations.

In the meantime, I have found a source that states an AFOV of 64 degrees for the 10x42 and 62 degrees for the 8x42.

I still wonder whether the difference in AFOV was the (only) reason, why I considered the view of the 10x version to be, say, more easy and immersive.

Lightbender, I have a 10x NV which I love. For lower magnification I went for the 7x42 UVHD+. That bin is definitely worth checking out vs the 8x NV. It’s a great combination IMHO. Check the many posts on here about it’s virtues!

Troubador said:

Take a look at the fov in metres at 1,000 metres of Zeiss SF 8x42 and 10x42 and the 8x is much bigger but Zeiss states that the AFOV for both is exactly the same.

Lee

Click to expand...

Hi Lee,

thats not correct, see "Subjektiver Sehwinkel".
https://www.zeiss.com/content/dam/media/Download/zeiss-victory-sf-technische-daten.pdf

Andreas