8x42mm bins...Zeiss FL v. Swaro (8.5) EL v. Leica HD? (1 Viewer)

Sancho · Nov 14, 2008

ThoLa said:
Sancho, face it: you'll need one of each!

Santa

I´m afraid the Clear-Out of Sancho´s Optics cupboard won´t cover that, Mr. Santa Sir...and anyway I don´t believe in You!!! (Gasps from the assembled Elves and Reindeer).

I think I´ll wait until these Fancy New Nikons come out early next year.

ThoLa · Nov 14, 2008

Sancho said:
I´m afraid the Clear-Out of Sancho´s Optics cupboard won´t cover that, Mr. Santa Sir....

So you#re telling me you need a new cupboard, too ?!

Hey, Rudi, it's going to be a really big bag we have to carry this year.

Sancho said:
I think I´ll wait until these Fancy New Nikons come out early next year.

Will they jump the gun and be in the shops before the new ELs?

(beware: there's a BIG hole in them!)

S. Claus

Sancho · Nov 14, 2008

ThoLa said:
Will they jump the gun and be in the shops before the new ELs?

S. Claus

According to Nikon Yourp, they´ll be available in February 2009. I found a spec of them online (see Nikon forum). In every respect they´re my dream 8x42mm bino (ED glass, great ER and exit pupil, open-bridge, FOV of 7.7 degrees). But almost as heavy as the EL 8.5x42. So we´ll have to wait and see.

Kevin Conville · Nov 14, 2008

Sancho said:
I think I´ll wait until these Fancy New Nikons come out early next
year.

I don't know if you're interested in the 7x42 EDGs as they are available now, at least in the States. I vote for you getting these, as I want to read your review! If you don't get the Nikons, help out Leica by buying theirs :t:

I think they may be the most financially fragile right now.

Addendum: Ah, for 8x42s, I guess you'll have to wait. BTW, considering the economic climate, do you think that maybe Nikon will yet again postpone delivery of the EDGs?

ThoLa · Nov 14, 2008

Sancho said:
According to Nikon Yourp, they´ll be available in February 2009. I found a spec of them online (see Nikon forum). In every respect they´re my dream 8x42mm bino (ED glass, great ER and exit pupil, open-bridge, FOV of 7.7 degrees). But almost as heavy as the EL 8.5x42. So we´ll have to wait and see.

fov 56,6 deg - not too impressive.

According to Swaro: new ELs in Oct 08 ......... Jan 09 ............ 2010.
According to Nikon: EDG in Feb 09.......
Yes, let's wait, .... wait .... w....

Gives me time to get rich in the meantime!

Best wishes, Tom

Kevin Purcell · Nov 14, 2008

ThoLa said:
fov 56,6 deg - not too impressive.

The arithemtic is a bit off ... so I checked the previously referenced site

http://www.nikonhunting.com/binoculars-edg-8x42.html

Real Angular Field of View 7.7
Apparent Angular Field of View 56.6

So they're wrong too. Wouldn't be the first time a marketer got that wrong

The EDGs either have a 7.1 degree FOV or 63.2 AFOV.

And might account for the "delay" (changing the aperture stop from 7.1 to 7.4) so now they look as wide as a Swaro EL with the same (widest) AFOV and the widest FOV of the Alpha 8x42s. Gotta look good on paper and "biggest" in the view!

Nikon EDG
FOV 7.7 degrees
AFOV 63.2 degrees

Zeiss 8x42 FL
FOV 7.7 degrees
AFOV 56.6 degrees

Leica Ultravid 8x42
FOV 7.4 degrees
AFOV 59.6 degrees

Swarovski EL 8.5x42
FOV 7.4 degrees
AFOV 63.1 degrees

Sancho · Nov 14, 2008

Kevin Conville said:
If you don't get the Nikons, help out Leica by buying theirs :t:

I think they may be the most financially fragile right now.

Addendum: Ah, for 8x42s, I guess you'll have to wait. BTW, considering the economic climate, do you think that maybe Nikon will yet again postpone delivery of the EDGs?

ThoLa said:
According to Swaro: new ELs in Oct 08 ......... Jan 09 ............ 2010.
According to Nikon: EDG in Feb 09.......
Yes, let's wait, .... wait .... w....

Gives me time to get rich in the meantime!

Best wishes, Tom

I think all bets are off until the new financial year. Then the extent of global balance sheet holes (never mind focussing-bridge holes) will be evident, and we´ll know just how deep this is....8x42 bins might be the least of our worries!

mak · Nov 14, 2008

Kevin Purcell said:
The arithemtic is a bit off ... so I checked the previously referenced site

http://www.nikonhunting.com/binoculars-edg-8x42.html

So they're wrong too. Wouldn't be the first time a marketer got that wrong

The EDGs either have a 7.1 degree FOV or 63.2 AFOV.

And might account for the "delay" (changing the aperture stop from 7.1 to 7.4) so now they look as wide as a Swaro EL with the same (widest) AFOV and the widest FOV of the Alpha 8x42s. Gotta look good on paper and "biggest" in the view!

Nikon EDG
FOV 7.7 degrees
AFOV 63.2 degrees

Zeiss 8x42 FL
FOV 7.7 degrees
AFOV 56.6 degrees

Leica Ultravid 8x42
FOV 7.4 degrees
AFOV 59.6 degrees

Swarovski EL 8.5x42
FOV 7.4 degrees
AFOV 63.1 degrees

Kevin.

Where did you get these figures from? 8x42 FL = 56.6 degrees!!!

it is: 135m@100m = 61.8 degrees

mak

henry link · Nov 14, 2008

Kevin,

Don't jump to conclusions about Nikon's math. See this thread:

http://www.birdforum.net/showthread.php?t=109343

Henry

Edit: The Nikon link in the thread above doesn't work. Try this one:

http://www.nikon.com/products/sportoptics/lineup/binoculars/img/chart_001.jpg

Kevin Purcell · Nov 14, 2008

mak said:
Kevin.

Where did you get these figures from? 8x42 FL = 56.6 degrees!!!

it is: 135m@100m = 61.8 degrees

mak

My own calculation from data on Eagle Optics web site

FOV = FOV in feet @ 1000 yds / 52.5
AFOV = FOV * magnification

You quote

135m@100m = 61.8 degrees

which isn't right

135 m @ 1000m (not 100m) gives a FOV of arctan(135/1000)

I do love Google Calculator

http://www.google.com/search?q=arctan(135/1000)+in+degrees

arctan(135 / 1000) = 7.68844777 degrees

and AFOV of 8 times that

7.68844777 * 8 = 61.5075822

Close enough for government work (they do like to round off number for the linear measurement why they just can't use degrees for FOV ...)

Kevin Purcell · Nov 14, 2008

henry link said:
Kevin,

Don't jump to conclusions about Nikon's math. See this thread:

http://www.birdforum.net/showthread.php?t=109343

Henry

Edit: The Nikon link in the thread above doesn't work. Try this one:

http://www.nikon.com/products/sportoptics/lineup/binoculars/img/chart_001.jpg

Thanks, Henry.

Interesting I'd not see that before. I guess the old way is an approximation because tan theta ~ theta (in radians) for 5 degrees or less (for theta < 0.1ish).

And if you follow the ISO recommended math on that graphic

7.7 degrees = 0.134390352 radians

2 * arctan(8 * tan(0.123918377 / 2)) = 52.791216 degrees

which is what Nikon quote. I stand corrected!

I wonder if that will punish them if other people do a similar calculation rather like ThoLa did

So all the AFOV numbers for the Alpha bins above (not the FOV) need to be reduced a bit. But they're still in the same ballpark (same FOV and same magnification so same FOV).

EDIT: I see the encoding system for URLs here seems to mangle Google calculator URLs when you edit them

Sancho · Nov 14, 2008

Kevin Purcell said:
...............why they just can't use degrees for FOV ...

I agree...speaking for the Mathematically Challenged, I can just about understand degrees, I test FOV by counting fence-posts, and I break out in a cold sweat when I see a diagram with lots of triangles and the expression "tan" written on it someplace....angular FOV works fine for me.

Kevin Purcell · Nov 14, 2008

Sancho said:
I agree...speaking for the Mathematically Challenged, I can just about understand degrees, I test FOV by counting fence-posts, and I break out in a cold sweat when I see a diagram with lots of triangles and the expression "tan" written on it someplace....angular FOV works fine for me.

It would be nice if they would all agree to do just that ... so we wouldn't have to make silly assumptions!

ThoLa · Nov 15, 2008

Kevin Purcell said:
The arithemtic is a bit off ... so I checked the previously referenced site

So they're wrong too. Wouldn't be the first time a marketer got that wrong

Well, ... no!

It's not a marketer's mistake (not this time).

It is in fact the simply multiplying (mag x "true" fov) we are used to that is wrong.

The 56,6° is the apparent field of you according to an acknowledged ISO protocol! (it is given as a footnote in the pdf I have added)

It is the apparent field of view in degrees which alone determines what the image looks like in the eyepieces.

You will find deviations of the apparent fov and the fov on the objectives' side in most catalogues. (For example the "true" fov of the new Swaro EL 8,5 is given as 7,6; multiplied by the magnification yiels 64,6°. The actual (apparent) fov is (accurately) given in the brochure as 60 degrees, i.e. that's what you or I will SEE).

People should realize there is a difference and get used to forget the fovs in "feet per square mile" or whatever nonsense is regularly circulated.

Time to see things as they are,
says
Tom

henry link · Nov 15, 2008

Even the ISO standard doesn't predict the AFOV with complete accuracy because it doesn't include the influence of distortion.

For a given true field, barrel distortion will cause the AFOV to be smaller than calculated and pincushion distortion will cause it to be larger. The extra apparent field added by pincushion might be thought of empty or artificial field, because it comes from objects growing larger toward the edge of the field, not from any real increase in field width. Binoculars can vary from having almost no pincushion to some wide field designs having quite large amounts added intentionally to reduce the "rolling globe" effect when panning. Even with a zero distortion design, AFOV can only be accurately calculated if the real field and the magnification are accurately specified, which is not always the case.

Since we aren't likely to achieve complete accuracy, I think, for comparison purposes we should just continue to use the easy arithmetic of multiplying the real field by the magnification to arrive at an approximate AFOV. After all, most manufacturers specs have been done that way for a long time and still are. In this case consistency is more important than absolute accuracy.

mak · Nov 15, 2008

Kevin Purcell said:
My own calculation from data on Eagle Optics web site

FOV = FOV in feet @ 1000 yds / 52.5
AFOV = FOV * magnification

You quote
which isn't right
135 m @ 1000m (not 100m) gives a FOV of arctan(135/1000)

Kevin.

Yes I missed out a zero (things happen - typo errors) riflescopes are based on 100m, but as this is a bird forum, lets not go there.

The easy calculation, which I use for dealers is: FOV (135m) / 17.45 (= 7.73 degrees) x mag (8) = 61.8 degrees (I think this agrees with the Zeiss web site 61.8). We could obviously go much deeper into this with the maths, but not on a general forum.

Another thing: wide angle field of view is 60 degrees or more (I believe the Japanese use a different figure). In the UK the easy way to remember the fov / figure (17.45) is to think of UK vat (17.5).

Your calculations came from a respected retailer, no doubt, mine came from my employer. I will stick with my employers training, if you don't mind. But the Zeiss FL range of 42mm & 32 mm models has wide angle field of view.

mak

Kevin Purcell · Nov 15, 2008

mak said:
Your calculations came from a respected retailer, no doubt, mine came from my employer. I will stick with my employers training, if you don't mind. But the Zeiss FL range of 42mm & 32 mm models has wide angle field of view.

No, my calculations came from my (PhD trained!) brain not some retailer. They just gave the givens (which are the same as the manufacturer distributes).

Along with hints from Henry Link on how to do the AFOV calculation properly at least according to ISO standard that Nikon uses (which is where this started) that gives smaller numbers than the simple but incorrect "easier" calculation (that both you use and I used earlier too).

Both Henry and I explained in an earlier posts that these don't work because they're based on an approximation that tan theta ~ theta that fails for FOV > 5 degrees. See the links provided by Henry too.

So I trust my calculations ...

Sancho · Nov 15, 2008

mak said:
.........the Zeiss FL range of 42mm & 32 mm models has wide angle field of view.

mak

So...how many fence-posts at the top of my street will I see with them?

. I propose that "Sancho´s Fence-Posts" be used as the International Reference Standard for FOV. So bins will henceforth be Two, Three or Four Sancho-Posts and we´ll all know what we´re on about. (Well at least I will.)

mak · Nov 15, 2008

Kevin.

In your earlier post you state FOV (ft) / 52.5. If you take the 8x42 FL measurement in feet (405) / 52.5 = 7.71 degrees x mag (8) = 61.7 degrees. Difference to my figures of 0.1 degrees, but a long way from 56.6 degrees.

Shall we agree to disagree?

mak.

8x42mm bins...Zeiss FL v. Swaro (8.5) EL v. Leica HD? (1 Viewer)

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