How are 4/3 and m4/3 lenses different?

[tom in mpls]

I have been enjoying my new E=P1 for a couple of days now, and understand that there are lots of Oly and other lenses that can be mounted on it. One thing is still not quite clear to me, though. How does a regular 4/3 lens differ from a micro 4/3 lens. Since they are both made for cameras with the same sensor size, why are they different?

I know there is a 4/3 to m4/3 adapter available, so they likelyy have different mounts, and must have a different focusing distance. The name suggests to me that for similar focal length lenses, the m4/3 version would be significantly smaller (hence "micro").

 

[pellicle]

flange distance and mount physical diameter are the major issues.

flange distance is:

This is the distance from the mounting flange—the metal ring on the camera and the rear of the lens—to the film plane.

 

[Terry]

Just to add:
Because the flange distance is shorter then the diameter of the lenses can also be smaller. Another way to think of it is in Leica M vs leica R terms. Both cover a full frame. One sits further out to make way for the mirror and hence the bigger R lenses. Because micro 4/3 flange distance is so short almost every lens made can be adapted to it because the requirement is to have the lens further away than micro 4/3 requires and adapters can compensate for the difference.

 

[tom in mpls]

Just to add:
Because the flange distance is shorter then the diameter of the lenses can also be smaller.

Because micro 4/3 flange distance is so short almost every lens made can be adapted to it because the requirement is to have the lens further away than micro 4/3 requires and adapters can compensate for the difference.

Key points, thanks.

 

[pellicle]

Key points, thanks.

just for my own learning on what is and isn't useful to others, was it that "the distance from the mounting flange...to the film plane" didn't make sense to you or was the wiki article not useful or both?

 

[Diane B]

Maybe this link showing visually the benefits--and differences of the m4/3rds system would be helpful.
http://www.four-thirds.org/en/microft/index.html#SlideFrame_9

 

[tom in mpls]

just for my own learning on what is and isn't useful to others, was it that "the distance from the mounting flange...to the film plane" didn't make sense to you or was the wiki article not useful or both?

I didn't notice the wiki link initially. Thanks.