Why insist on FF format?

Started Sep 22, 2012 | Discussions thread
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Re: Why mention FF in this forum at all?
In reply to rocklobster, Sep 24, 2012

rocklobster wrote:

M4/3 does not pretend to be FF and FF cannot be squeezed into a M4/3 camera body with small lenses despite Sony's effort with the RX1 which I strees is a fixed lens unit which would have some serious distortion compensation smarts in camera to accomodate such small optics.

The "small optics" comes from the fact that the RX1's lens doesn't have to be a retrofocus lens, not because it's skimping on the internal optics. DSLR lenses use retrofocus lenses because they have to be positioned far enough away from the sensor/film plane to leave room for the reflex mirror. As a result, the optics have to be made much larger. But with camera systems that don't use a reflex mirror (like Leica rangefinders), you don't have to use retrofocus lenses. You can use "true" lenses, which can be made much smaller. See diagram below.

This is why Leica M and other rangefinder lenses can be made so small. Part of the reason is that they don't need autofocus motors inside them, but a major reason is that they are "true" lenses rather than "retrofocus" lenses. They are small even though they are still 35mm full frame lenses!

Likewise, since the RX1 doesn't have a reflex mirror between the sensor and the lens, it can use a "true" lens rather than a "retrofocus" lens. However, we also have to remember that, unlike Leica M lenses, the RX1's lens has an autofocus motor inside it, as well as an optical image stabilization system inside it as well, both of which add girth and size to the lens. But we can definitely see the potential of an interchangeable lens mirrorless version in the future. Here is the RX1's Carl Zeiss lens detached from the RX1 body.

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