infinity on the sony 18-200 lens

Started Mar 14, 2013 | Discussions thread
shibbs
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Re: infinity on the sony 18-200 lens
In reply to viking79, Mar 14, 2013

viking79 wrote:

shibbs wrote:

Hi how do I find infinity on the sony zoom lenses, I wished they were marked.

It isn't marked as it is not in a specific spot. The ring you turn is just an encoder that creates an electronic signal that is used by the motor to move the lens. There is no absolute start/stop point to it, it is all relative.

The camera body could maybe figure out where the lens is and display it on the screen, but this depends on what information it has available. The issue is the camera doesn't really know where infinity focus is going to be, at different zoom levels it could be at different points, etc. To do this they would probably have to calibrate each lens and body.

On my Samsung NX, only 2 lenses display focus information on the screen that I am aware of, and both those lenses use USM focus and not stepper or linear motors so they are mechanically coupled and have a "real" focus ring. The downside is these lenses focus relatively slow. I think Fuji also puts distance indicators in the viewfinder/display, but there might be some accuracy issues with those.

I agree, they should be marked in some way (or give the camera an option "lock at infinity" or similar), but there are technical complications in doing this.

Eric

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Thanks for such a quick reply.  I think you covered it all for me.

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