Great pictures, especially the enhanced hearing one 👍
John. That enhanced hearing thingy is hilarious!In relation to the posts above, some images of devices with significantly altered stereopsis compared to regular Porro prism binoculars:
a) When Zeiss commenced production of Porro prism binoculars in 1894, they also offered a handheld Stereo Telescope, aka a Relief-Fernrohr
(it uses a variation of the Porro Type II prism, with one of the four right angle prisms located at the front of the objective) *
b) While the above never saw much civilian use, by 1904 it had been enlarged and was used in mounted form for military use.
See an image from a catalogue by Cassidian Optronics (the catalogue from 2012 is titled Handheld Targeting Systems,
and on the front page it indicates 'Optics by Carl Zeiss').
c) Enhanced stereopsis was essential to the operation of coincident image rangefinders (aka telemeters).
Depending on the task they went all the way from handheld sizes, as shown in the Cassidian image; to as Bill indicates those for shipboard use.
See an image from 1912 at: USS Nebraska Naval Ship Cover 1912 From Ship Post Master Range Finder RPPC | Topics - Transportation - Boats, Postcard
d) And the Pentax Papilio reverse Porro prism binocular uses significantly altered stereopsis in a different way.
To achieve a minimum focus of only 50 cm/ 20 in, the objective lenses in each barrel move closer together.
See the images in post #4 at: Where are the aspherics?
And finally, there were not only stereo enhancements to vision! See an image from: https://mobile.twitter.com/beidaihebirder
* In the early 20th century Zeiss also offered other hand held binoculars with exaggerated stereopsis.
See post #91 at: New Horizons II
Hi Arthur,Hello John,
I believe those trench periscopes are known as "donkey ears." Do you recall the minimal focussing distance and how natural was the view at its minimal distance?
Do we see an exaggerated "3D" with Porros or diminished "3D" with roofs?
Is the focuser in a 10x binocular really capable of increasing the image distance by as much as 10x?Technically, an observer can use his focus knob to push the virtual image back and put it in a location that is consistent with L-R parallax between the two barrels.
In other words do we see an exaggerated "3D" with Porros or diminished "3D" with roofs?
Offhand, here's a few more visual cues for depth that are not stereo based:We use 2 other ways to see depth:
-Parallax: When driving the trees near you move faster than the sun far away.
-Overlay: You can see that a big tree far away is hiding behind i.e. a building.
The human eye only uses the stereopsis for nearby objects. Because the difference for the image received in each eye is more different looking to nearby objects.
Hypermetropia? Plus lenses?I see a 2 times magnified image by holding my distance glasses 8 inches in front of my eyes.
With greatly increased stereo also.
Even though I own many more Porros than roof prism binoculars, over the years I've come to dislike the increased stereopsis of Porros over roofs even though I wasn't sure which spacial presentation was more "accurate".