When do an 8.5x and 8x bin have the same magnification?
When marketers don't quite tell the whole truth. I just happened to browse these two Nov 2010 reviews at allbinos.com one after the other.
Kowa Genesis 8.5x44
http://www.allbinos.com/index.php?t...etki&test_l=156
Real magnification 8.36+/- 0.15x
Minox BD 8x44 BP (very similar to the Leupold Cascades porro)
http://www.allbinos.com/index.php?t...etki&test_l=166
Real magnification 8.39+/- 0.2x
That makes me feel a bit better about the narrow FOV!
It could be just measurement error with one at the top of the error bar and the other at the bottom. But both are more than one standard deviation way from the marketers magnification.
What about other 8.5x magnification bins?
Swift Optics 828 HHS Audubon 8.5x44
http://www.allbinos.com/index.php?t...etki&test_l=167
Real magnification 8.83+/- 0.2x
Swift Optics 820 Audubon 8.5x44
http://www.allbinos.com/index.php?t...etki&test_l=159
Real magnification 8.82+/- 0.15x
Swift Optics 820 ED Audubon 8.5x44
http://www.allbinos.com/index.php?t...etki&test_l=158
Real magnification 8.8+/- 0.15x
The Weaver 8.5x is right on the money and the Bushnell 8.5x is 8.6x
http://allbinos.com/162-binoculars_...lam_8.5x45.html
http://allbinos.com/160-binoculars_...ity_8.5x45.html
Well, they shouldn't fib should they? And the top brands always come out spot on in these tests.
But just try to imagine the world of an optical instrument designer. He might start out with the goal of a certain magnification, get into the design, start doing all the compromises, trading a tad of astigmatism here for a smite of curvature there, and at some point says hey, if I tweaked the magnification a little I could get better _______. I mean, it might well be regarded as a "slightly free" parameter, nothing really holy about it up to a point. Nobody is going to notice a slight bending from the exact intended power.
Now to the imagined world of the marketeer. The damn thing is 8.36x. What is he supposed to do with that? Just that number, so odd, so exact, seems silly, raises silly questions, and calls attention to the magnification in a way that does not help sell the binocular to the public.
Anyhow, somewhere out there there (out here?) will be a hypersensitive nutcase who always thought 8 was not enough, and 8.5 was a little bit too much, and pronounces the binocular "very steady for the magnification", or, if the magnification is 8.82, "able to show detail that other 8.5s cannot"!
Ron