IN PRAISE OF THE SWAROVSKI 12X42 NL PURE (1 Viewer)

[Will K]

the 12x42Nl has a FOV of only 330 ft, but its AFOV is 71, which might be one of the highest AFOV of any binocular

I posted something on this topic recently elsewhere, in reference to the Nikon WX 10x50 (76.4 AFOV).

Just out of curiosity, what are the other contenders for highest overall AFOV?

 

[William Lewis]

I posted something on this topic recently, in reference to the Nikon WX 10x50 (76.4 AFOV).

Just out of curiosity, what are the other contenders for highest overall AFOV?

NL, sf, Eii. There are many wide field classic porro's. I believe the wx is the widest and best corrected of them all followed by NL 8x42, sf 8x32 and Eii 8x30 - the Eii is not the best corrected of them but not by any means badly corrected - off axis blur goes virtually goes unnoticed in use.

Will

 

[Canip]

Nikon WX 10x50 (76.4 AFOV)

The 76.4 degrees are Nikon's own specification (I guess in line with the ISO norm), but as Glenn LeDrew wrote on CloudyNights, Nikon is criminally understating the true AFOV, as you can easily measure yourself (my measurement, slightly rounded: 85.1 degrees).

Canip

 

[Will K]

The 76.4 degrees are Nikon's own specification (I guess in line with the ISO norm), but as Glenn LeDrew wrote on CloudyNights, Nikon is criminally understating the true AFOV, as you can easily measure yourself (my measurement, slightly rounded: 85.1 degrees).

Canip

Wow, that’s quite something! I’m curious to try one. Although they are extremely - astonishingly - expensive, so maybe that’s not a good idea. I might like what I see.

 

[Will K]

Nikon WX | Astronomy Binoculars | Super-Wide FOV

Nikon WX, astronomy binoculars, super-wide field of view, ED glass, Field Flattener Lens System, multilayer coating, Abbe-Koenig prisms, magnesium alloy.

www.nikon.co.uk

That’s almost 3.5x the price of an NL 12x42. If anything, AFOV can be be expensive.

 

[BabyDov]

The 76.4 degrees are Nikon's own specification (I guess in line with the ISO norm), but as Glenn LeDrew wrote on CloudyNights, Nikon is criminally understating the true AFOV, as you can easily measure yourself (my measurement, slightly rounded: 85.1 degrees).

Canip

Why do you think Nikon would understate the AFOV by so much? You would think that if any binocular had a AFOV of 85, Nikon would want that known, since their AFOV is so beyond any other binocular's, it puts theirs in a class by itself.

 

[BabyDov]

NL, sf, Eii. There are many wide field classic porro's. I believe the wx is the widest and best corrected of them all followed by NL 8x42, sf 8x32 and Eii 8x30 - the Eii is not the best corrected of them but not by any means badly corrected - off axis blur goes virtually goes unnoticed in use.

Will

William,
I believe the 12x42 Nl beats the 8x42Nl, 71 vs 69. It doesn't sound like a big difference in AFOV, but I can easily see the difference. (I own both.)
The much greater magnification may also contribute to that impression.
Bill

 

[Will K]

I believe the 12x42 Nl beats the 8x42Nl, 71 vs 69

That was my impression, too, both from the stats provided by Swaro and from previous discussion

 

[henry link]

Why do you think Nikon would understate the AFOV by so much? You would think that if any binocular had a AFOV of 85, Nikon would want that known, since the AFOV is so beyond any other binocular's, it puts theirs in a class by itself.

Nikon adopted the ISO standard (ISO14132-1:2002) for estimating AFOV about 15 years ago and have blindly stuck to it. Canon uses the same method, perhaps a few others. It virtually always understates the true measured AFOV and falls even farther below the inflated simple calculation to the marketing detriment of those who adopt it. Why do they continue? Bureaucratic inertia?

 

[GrampaTom]

The much greater magnification may also contribute to that impression.
Bill

I bet yes...

 

[William Lewis]

William,
I believe the 12x42 Nl beats the 8x42Nl, 71 vs 69. It doesn't sound like big difference in AFOV, but I can easily see the difference. (I own both.)
The much greater magnification may also contribute to that impression.
Bill

Quite correct bill.

I missed the apparent bit of Will's question. I've ordered them in terms of field of view -how much of the world you actually see rather than apparent field of view - how wide your view of the world appears to be. There are lower magnification instruments that are wider still.


Will

 

[GrampaTom]

Nikon adopted the ISO standard (ISO14132-1:2002) for estimating AFOV about 15 years ago and have blindly stuck to it. Canon uses the same method, perhaps a few others. It virtually always understates the true measured AFOV and falls even farther below the inflated simple calculation to the marketing detriment of those who adopt it. Why do they continue? Bureaucratic inertia?

Great question.. Still trying to figure out its significance of AFOV but thanks to this conversation think Im getting closer. Henry your statement that AFOV was the most important form of FOV for you was initially a puzzle, but one that caused me to try and understand. If you feel this way there must be a reason. Thinking about the subject, the confusing conversation that has gone here, not just recently but off and on, it seems not many people get it and therefore miss the significance. I wonder if the bino company marketing departments are equally, ill informed, or just sort of ambivalent, see it as a thing for a smaller percent of the market.

I have a question:
That TV analogy sprang to my head after thinking about this conversation, playing here within the apt with my limited AFOV choices, and watching TV on a friends 60" TV. My subsequent realization that I'd made a mistake because of the blank wall behind the scope/target, thinking wrongly it was "air" but then rejoined the idea the whole view, background and target expands do to AFOV, Im feeling better.... I hope. Durobird, Canip, Babydov seemed to like the TV analogy, whereas you got to answering the more explicit questions of the range of optics you use to appreciate AFOV from my post on it. How do you feel about the large screen TV analogy?

T

 

[henry link]

The TV analogy only works for one special condition when both the AFOV and the magnification increase by the same amount so that the content of the field remains constant. Check out the image below from Olympus marketing material I found online. It shows the effect of an increase in apparent field when the magnification remains constant so that the content of the field expands.

 

[BabyDov]

Great question.. Still trying to figure out its significance of AFOV but thanks to this conversation think Im getting closer. Henry your statement that AFOV was the most important form of FOV for you was initially a puzzle, but one that caused me to try and understand. If you feel this way there must be a reason. Thinking about the subject, the confusing conversation that has gone here, not just recently but off and on, it seems not many people get it and therefore miss the significance. I wonder if the bino company marketing departments are equally, ill informed, or just sort of ambivalent, see it as a thing for a smaller percent of the market.

I have a question:
That TV analogy sprang to my head after thinking about this conversation, playing here within the apt with my limited AFOV choices, and watching TV on a friends 60" TV. My subsequent realization that I'd made a mistake because of the blank wall behind the scope/target, thinking wrongly it was "air" but then rejoined the idea the whole view, background and target expands do to AFOV, Im feeling better.... I hope. Durobird, Canip, Babydov seemed to like the TV analogy, whereas you got to answering the more explicit questions of the range of optics you use to appreciate AFOV from my post on it. How do you feel about the large screen TV analogy?

T

Tom,
We have discussed this ad nauseum, both in this forum and personally. Your analogy is absolutely on target! Don't back off just because one guy doesn't like it or thinks we don't need analogies to understand AFOV. In fact the more, I think about it, the better I like your analogy.

BTW, I think analogies are important in trying to understand abstract concepts, whatever they are. As a pediatrician, I always used them, when appropriate, to help patients better understand both their problem and treatment.

 

[BabyDov]

The TV analogy only works for one special condition when both the AFOV and the magnification increase by the same amount so that the content of the field remains constant. Check out the image below from Olympus marketing material I found online. It shows the effect of an increase in apparent field when the magnification remains constant so that the content of the field expands.

I am not sure that picture is just showing increased AFOV, even though it says so. Beyond the white circle, it seems to show more FOV, too, doesn't it? I didn't think.that real FOV increased just because AFOV increased for the same magnification. Am I missing something?

 

[mwhogue]

I am not sure that picture is just showing increased AFOV, even though it says so. Beyond the white circle, it seems to show more FOV, too, doesn't it? I didn't think.that real FOV increased just because AFOV increased for the same magnification. Am I missing something?

Thanks for asking. I have the same question but as a technical illiterate was afraid to ask.

Mike

 

[henry link]

I am not sure that picture is just showing increased AFOV, even though it says so. Beyond the white circle, it seems to show more FOV, too, doesn't it? I didn't think.that real FOV increased just because AFOV increased for the same magnification. Am I missing something?

I'm not sure I can think of a way to make the relationship between AFOV and RFOV any clearer than that illustration, but maybe numbers will work better than pictures.

Imagine the fields represented by that picture are from an 8x binocular. Using the simple method an 8x binocular with a 50º apparent field will have a real field of 50º divided by 8 = 6.25º real field. An 8x binocular with a 60º apparent field will have a real field of 60º divided by 8 = 7.5º real field. If the magnification is constant then a change in AFOV results in exactly the same percentage change in the RFOV, in this case a 20% increase in AFOV results in a 20% increase in RFOV.

 

[tenex]

However, do you really mean you can tell that a particulary bino is a wide view or not by knowing its AFOV alone?

It's become clear that even this question is subject to confusion. Some said YES above because they thought you meant "is a wide field binocular", which is defined in terms of AFOV as I said; but if by "is a wide view" you only mean has a wide real field, then the answer is NO, you cannot, not without factoring in its magnification. But often when making such comparisons one is thinking about one particular magnification like 8x, and in that case YES, an 8x bin with a wider AFOV than others will also have a wider RFOV.

That is true for the same simple mathematical reason that everything else we've said here is; it all boils down to this one equation (only an approximation to the ISO/tangent formula, but even that isn't exactly right due to eyepiece distortion, so if necessary just ignore the trigonometry and accept that the following will do well enough):

AFOV ≈ mag * RFOV

Apparent and real fields are roughly proportional, according to the magnification of an instrument. That's what magnification is, what it does: it makes everything look so many times bigger. Once you understand this it's really simple, and there can be no further confusion.

I didn't think.that real FOV increased just because AFOV increased for the same magnification. Am I missing something?

Apparently, because of course it does. That's exactly what the equation says. (See Henry's sample calculation in #277.)

Analogies matter, are useful.

I see nothing wrong with the Tom's TV analogy.
You are seeing the same picture through two different size windows.

No, we are not talking about alternate modes of learning here. Analogies don't help when you can't even tell whether they're correct, because you don't understand the underlying principle yet. (The diagram in post 234 could help, because it correctly illustrates the relationship involved.) I am not going to dissect the faulty TV analogy again; even Dorubird's window analogy doesn't convey the role of magnification, which is central to all the confusions here. Few other things work quite the way telescopes do, so you're really not going to understand them by analogy. You simply have to learn how they work.

 

[BabyDov]

Tenex,
I really appreciate your explanation.
Bill

 

[Will K]

Inspired by Dorubird's artistic photos of the Habicht and other members' portraits, I thought I'd try my hand at composing a few of the NL 12x42. Hope you enjoy these first efforts!