How is the OMD so fast

Started Jan 7, 2013 | Discussions thread
rrr_hhh Veteran Member • Posts: 6,022
Re: How is the OMD so fast

zenpmd wrote:

What do you mean by focus by wire? As opposed to what

It is not fully mechanical with an helicoïd like in the traditional lenses. When you are focusing manually, the focusing ring transmits your movements to the processor and the processor moves the lenses elements forwards or backward. The main point is that you loose the feedback from the lens; there are no end stops either at infinite or nearest focusing distance. On very long lenses, you can spin and spin the focus ring without knowing where you are, whether you are too far away or too near. On shorter lenses this is less of a problem.

In the case of the 20mm Panasonic, the lens elements seem to be activated by a spring, as is shown here . But not all have that type of design. In fact, that 20mm is an older design. How the lens is pushed forward and backward that fast in mft lenses isn't entirely clear to me. For sure the focusing lens elements have to be moved, but how ? They could even use magnets in newer lens designs ? and adjusts the movements electronically ?

Olympus has issued two special lenses (12 and 17mm)  which have a snap focus ring which tries to give you that feedback again and unveils distance scales when you push/pull it (although they aren't very precise), they should allow photographers to use zone focusing like with old legacy lenses. But it is just an improved focus by wire design, not the old mechanical design.

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