Dumbest Question Ever -about lenses

[inkista]

Originally Posted by datiswous

What's so unique about it? I thought it would be possible for every brand dslr to mount old and new lenses of different brands via adapters on the camera, well maybe appart from these "full-frame sensor" -dslr's.

You can always adapt, but you won't be able to focus out to infinity. In fact, you may only be able to focus out to a few inches.

The key is the distance from the image plane (sensor) to the back element of the lens. This distance is precise and must be maintained in order for the lens to achieve inifinity focus. Think of using extension tubes for macro capability--once you move the lenses away from where they're designed to sit, you lose the ability to focus out to infinity.

The Four-Thirds system, because of its smaller sensor, has a smaller "back focus" distance than any other digital APS-C/full-frame mount system and most film SLR systems (it's still larger than rangefinders, though, which is why micro Four-Thirds has been exciting everybody with rangefinder glass).

An adapter has to take up physical space. The ring needs to be a specific thickness between the lens and the camera. So, you can really only adapt one system to another (without adding glass between the lens and the camera) if the adapted system has a larger back focus distance than the system you're adapting to, and the adapted system probably has to be larger by at least 1mm, due to machining limits of accuracy.

The practical upshot is that Nikon users can't adapt anything without modifying mounts of either the camera or the lens or using glass elements (which decreases image quality). Canon can usably adapt six or so lens mounts, but cannot adapt Minolta MD or Canon FD or Four-Thirds. And Four-Thirds cannot adapt rangefinder glass, like Leica M or M39 lenses.

[WolverineX]

Originally Posted by inkista

You can always adapt, but you won't be able to focus out to infinity. In fact, you may only be able to focus out to a few inches.

Actually there are adapters now that have Dandelion chip on them that allows AF confirm and infinity focus

Originally Posted by inkista

The practical upshot is that Nikon users can't adapt anything without modifying mounts of either the camera or the lens or using glass elements (which decreases image quality). Canon can usably adapt six or so lens mounts, but cannot adapt Minolta MD or Canon FD or Four-Thirds. And Four-Thirds cannot adapt rangefinder glass, like Leica M or M39 lenses.

Also there is a special adapter for Four-Thirds that allows all legacy lenses to be used on dSLR , it looks a bit like a Frankenstein because it uses 8 screws to attach the adapter to the lens

you can see it here

[inkista]

Originally Posted by WolverineX

Actually there are adapters now that have Dandelion chip on them that allows AF confirm and infinity focus

Actually all the chip does is fake a lens chip. It allows for AF confirmation and, in the case of Olympus bodies, stabilization, but as I described, infinity focus relies on the distance the lens is held from the body. If the adapted system's backfocus distance is smaller than the mount being adapted to, focus to infinity is not possible without glass elements. The chip has nothing to do with it. For Four-Thirds, nearly eveybody's is bigger, which is why the rings can give you "infinity focus", but this is NOT the case for other mount systems.

You cannot jam a lens farther into a camera body because the mount hole is typically too small, and even if it weren't, you'd probably end up whacking the mirror box assembly into the back of the lens.

And I can absolutely guarantee that that "universal" adapter won't let you mount legacy rangefinder glass (M39, Leica M, etc.) onto a Four-Thirds mount, for exactly the same reason. If you note, those lens systems are not mentioned. Nor, can you use an adapter ring with lenses that don't have an aperture ring (Canon EOS, Nikon G-mount, etc.) because you won't have a way to control the aperture. So, no, not "all legacy glass". Just more than other mounts. As I said upthread.