Subject: RE M22 retirement
From: John Gruver <gruver@___com>
One further add to the Steiner M22 debate. I was close friends with the product manager of Pioneer/Steiner during the purchasing of the M22. It was made according to DOD specs, which specified a laser protection element ( heavy filter at 623nm) They (DOD) were freaked out at the time, having just recently (1987-9) been lased many times by the Ruskies and Koreans at check points, on helicopters and such. Early laser-eliminating technology cut heavily into the light-gathering ability, reducing it from 97+% to below 93%. Even then it was called a dog, but thats what they wanted at the time. Should have been removable, like the dark sun filter add-ons of WWII, but was incorporated into the glass that I know.
Subject: Orion 7x32 Expanse, others.
From: "Pete Rasmussen" <eyepetes@___as.net>
Just like the Bushnell Xtra-Wide series these babies use a mirror in replacement to one BaK-4 prism for each half of the system. Quite sad this and other companies won't declare that fact in application in their advertisment print but seems on par with much of what goes on currently. One other biggie example regards nomeclature for coatings where some will call there products "fully multicoated" when obviously are lesser so.
Anyhow, the effective removal of one prism here seems to favorably allow for a noticeable reduction in chromatic and spherical error. A good thing. Interestingly there is an Olympus 8x25 WA (and other relabelled brands around I believe) with mirror substitution for prism design that seems plausible as being same as the Orion 8x25 (72°). That one newly listed along side the 7x32 Expanse. The Olympus product I examined showed to have poor field sharpness where image was crisp only on very center.
Mixed to poor feelings abound for me with these hybrids. But, expectable due a lower power base, a Bushnell 5x25 Xtra-Wide proved a little better overall.
My preferences definitely still hold favorable toward a fully prismatic EWA binocular similar to the older yet overall superb 7x35 Tasco No. 110. But performance enhanced due full multicoatings of course!
From: "William Cook" <billcook50@___l.com>
>>>Interestingly there are still MANY "experts" who insist that a larger
>>>objective will provide increased resolution and "reach" even in daylight
>>>with a magnification producing exit pupils larger than the "average" eye
After being in optics for a very long time, I would hate to become an expert at the expense of having my "expert" placed within quotation marks. Be that as it may, the preceding sentence should probably read:
". . . optical professionals recognize that, all things being equal, an increase in aperture will increase resolution to a point limited by diffraction, atmospheric distortions, or sales brochures