I suspect we are not communicating about the same thing. The question was about _viewing_ through a wide angle peephole in a door, not taking pictures. Let me quote for you again: > Does anybody know why the image in an apartment door peep-hole > is not inverted? Is there a tiny little penta-prism in there? When you view images set for film (on your ground glass) through a converging lens system, the image is indeed upside down. When you place a second converging lens in the system between the first and the image plane such that the second focuses on the virtual image from the first and upon the film plane the image is indeed "right side up". When you view the images through your eye, you use your eye's lens as part of the closer converging lens and indeed you do form an image "right side up" on your retina. Now here comes the tricky part... Your eye, when used without any lenses forms an image "upside down" on your retina! Your brain translates this into the _perception_ of "right side up"! Now, that "right side up" image you presented to your retina is perceived as, you guessed it, "upside down"! Are there other ways that the optics (including your eye) can be arranged? Yes. They could be arranged as a three convex group system with two virtual images, but then I was relating to most normal arrangement of optics and to arrangements comparable to the original poster's question. If you wish to argue some different arrangement feel free to do so. If you don't change the topic you'll confuse the hell out of me though, because I'll be stuck on thinking you are still trying to be helpful to the original poster. Good topic in it's own right, though. It's all about light, and lenses make the light form images for us. Regards, Bob... From: "Don Roberts" <droberts@soli.inav.net> > Ok, Bob, I have been wrong many times in my life and usually learn from the > experience. Now would you care to elaborate so that I might profit from this > one? Are you saying that the construction as I described it is wrong or that I > can't take the photos that I have taken with such a device? I might have to > equivocate by saying that I have taken photos through these viewers mounted on > a lens cap and then mounted in front of a lens. I can't remember for sure if I > have done it with only a body cap. Don > > Bob Blakely wrote: > > > Sorry, You are... > > ...wrong where it comes to viewing the image through an eyepiece on the > > device. > > > > Regards, > > Bob... > > > > From: "Don Roberts" <droberts@soli.inav.net> > > > > > My understanding of this is that there are simply two lenses. The first > > would > > > invert the image and the second would invert it again making it rightside > > up. > > > And I hate to disagree with authority but I have used these things mounted > > on > > > body caps and on lens caps to make surreal fisheye images. Don
