On 1/1/2015 2:47 PM, Bob Whitmire wrote:
Been looking at binocs, and noted these, which have many features Joan really wants, are neither
waterproof nor fog proof. I think that might be a real disadvantage, even a deal breaker, for the Outer
Hebrides. For that matter, the coast of Maine. <g> No one seems to have any glasses that focus that
close. The best I’ve found are some brands—waterproof and fog proof—that focus down
to five or six feet. Quite a bit of difference.
You've put your finger on the reasons we have both, and are often carrying two
different kinds.
The problem with really close focus on conventional designs is the distance between objective lenses. You would start
to get weird parallax stuff that your eyes can't handle.
It's all trade-offs. Regular porro prism binoculars have wide objective spacing, and so give good 3D/distance views. But
they never focus very close. Roof prism designs bring the objectives closer together, and thus often focus closer. But
as you say, never closer than six feet or a little under (partially depending on your eyes.)
Reverse porro designs bring the objectives even closer together, but are usually used only for compact, relatively
inexpensive designs, at least in part because they start to lose a sense of depth in the view. I have an old, cheap pair
from the old Nature Company, 7x25, and focusing to somewhere between 4 and 5 ft. I took them as back-ups to Costa Rica.
They proved to be primary in rainforests. My other pair didn't focus very close, and there were all sorts of interesting
things to see in the "close enough to want to see, but to difficult/dangerous to get closer" category, especially in a
boat in seaside rain forest. :-) Interestingly, although not sealed, they never clouded up, even in considerable heat
and 100+%* humidity. Maybe it's that they are so cheap and unsealed?
That's where the Papilio design is unique. It starts with a reverse porro prism layout. Then, it focuses by moving the
the objective lenses forward to focus closer. As they do so, they also move closer together. That's the reason for the
relatively small objective diameters, 25 mm. I'm sure it's why the 8.5x model is the same. Undoubtedly the same 'front
end' with stronger eyepieces.
As far as I know, no one has managed to fully seal porro prism binoculars. The Papilios are relatively well designed for
water resistance. The objectives do their fancy dance behind a window of sealed, flat glass, so the front is impervious.
And they are well made, with no obvious weaknesses, but not fully sealed, let alone nitrogen purged. We've had no
trouble, but never exposed them to anything seriously challenging. They've been used on coastal Maine, but only in the fall.
Then again, there's nothing else remotely like them covering the range between binocular microscopes and regular
binoculars. The view of close-ish things is amazing - first class optics. Carol was carrying them on our New Year's walk
yesterday, and exclaiming as usual about the beautiful things out of reach off the boardwalk that she could see close-up
and clear. Me? I'm mostly looking through a camera's lens in macro mode. :-)
Are there others out there whose mileage varies?
If/when we go to Scotland, the Papilios will come along.
B. Vision Moose
* That's when nothing - NOTHING - is ever quite, really, DRY. It gets pretty darn humid ,uncomfortable for me, in parts
of the US, but this is a whole 'nother level. I know I've mentioned the Nikon electronic film camera that went insane
out in the forest.
--
What if the Hokey Pokey *IS* what it's all about?
--
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