........ Also, the Zeiss 10x42 SF(AFOV 65 degrees) would fill the bill also so I guess it is WOW.
Zeiss specs can be confusing because they sometimes use their own definitions, but do not explain them. In the case of the SF, they are showing "subjective viewing angle" rather than just viewing angle.
The Zeiss SF 10X42 has a field of view at 1,000 yards of 360 feet. This was verified in the Allbinos review.
Angle of view is computed by dividing the field of view (in feet) by 52.5. In the case of the 10X42 SF, this would be 360 ft divided by 52.5, giving 6.86 or rounded off, an angle of view of 6.9 degrees. (This compares to a subjective viewing angle of 6.5 shown in the Zeiss specs.)
The simple method to calculate the apparent FOV is to multiply the angle of view (6.9) by the binocular power (10X). This gives a simple apparent field of view of 69 degrees for the 10X42 Zeiss SF.
Using the same method, the simple apparent FOV of the Swaro EL SV 10X50 with a FOV of 345 ft is 66 degrees (345/52.5 =6.6 * 10 = 66 degrees). The result for the Canon 10X42 L IS at 341 ft (per B & H Photo) is 65 degrees (341/52.5 = 6.5 * 10 = 65 degrees).
Summary - Apparent FOV Using Viewing angle times power
- Zeiss SF 10X42 - 69 degrees
- Swaro EL SV 10X50 - 66 degrees
- Canon 10X42 L IS - 65 degeees
Here are the specs for FOV in degrees that are given in the manufacturers specs. They are based on something other than the simple method.
- Zeiss SF 10X42 - 64 degrees (from an older version of the website)
- Swaro EL SV 10X50 - 62 degrees
- Canon 10X42 L IS - 59.2 degrees
Which ever method is used, the SF has a larger apparent FOV which should give it a little more WOW.