This is similar to what we use on our night vision goggles.
Here's another use for an afocal optical device.
I think you're misinterpreting Point 2 by Chris. The point of the rear element extending backward is to make it possible to fit a small wide angle lens on an slr. Wide angle lenses are huge in SLRS versus rangefinder cameras because of the long flange focal length of SLRS. Rangefinder wide angle lenses can sit mostly inside the camera because there is no mirror that flips up that would hit them. Because an SLR wide angle lens is constrained to be far away from the film plane they are designed to be retrofocus, i.e. they are like reverse telephoto lenses.
This design helps eliminate fall-off and vignetting but it also makes for very large lenses. To allow for smaller wide angle lenses Canon designed EF-S to move the rear element closer to the film plane like rangefinder cameras. The point is NOT to get the same field of view with the same focal length as on 35mm. The EF-S 18-55 still gives the field of view of 29-88mm (according to the Canon website, link below). The point is to allow for a small wide angle lens. Yes, being closer to the film plane improves clarity on the wide angle side of EF-S zooms most tests find, but it doesn't give you 35mm field of view.
Don't believe me? Check out the Canon press release on EF-S lenses. Reducing size and weight is their explanation for using the EF-S design. Don't you think it'd be strange for them to leave out a feature as amazing as eliminating the crop factor on aps-c sized cameras?
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