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

s_grins wrote:

rrr_hhh wrote:

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 ?


I think that 1.7/20 lens is driven by screw motor (it sounds like s crew motor when active). IMO the spring you relate to, is a common place in situations when screw/nut couple needs precise movement. This spring eliminates flex between two.

Read the text of Roger Ciccala which I linked above : he explains very well how the 14mm and 20mm are focusing : here is what he is saying and there are several pictures of the unmounted lenses :

Notice the small, square posts with holes in the center that are set in the focusing ring. You can see four of them in the image above. We can lift the central part of the lens out of the housing now, which shows us the grooves in the focusing ring. Pancake lenses don’t have helicoids; the lens slides forward and backward during focusing because when the ring rotates, curved grooves inside move the lens backward and forward.

Also he makes it clear how the info is passed from the focusing ring to the processor : there is a dented ring inside of the lens which turns as you turn the focusing ring, passing in front of an optical sensor which transmist the info to the processor.

So well, the lens isn't activated by magnets.. at least not in the case of the two Panasonic pancakes lenses.

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