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March 23rd, 2010, 04:18 AM
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#1 |
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New Boot
Join Date: Apr 2007
Location: London, UK
Posts: 20
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Rack Focus
rack focus is a nice effect but when I do it the image kind of shifts. Increases and decreases a bit like I'm using the zoom, which i'm not. I don't recall seeing this when I've seen similar shots on tv. am i doing something wrong? I'm using a Sony DSR 500 if that helps.
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March 23rd, 2010, 06:19 AM
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#2 |
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Inner Circle
Join Date: Aug 2005
Location: Atlanta/USA
Posts: 2,515
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When you focus, you move a lens in a lens assembly. Depending on the build of the lens assembly, zooming may or may not also happen at the same time.
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March 23rd, 2010, 06:49 AM
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#3 |
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Major Player
Join Date: Mar 2007
Location: North Hollywood, CA, United States
Posts: 807
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It's called lens breathing. Most lenses suffer from this to some extent. Really expensive lenses have measures to prevent this from happening.
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March 23rd, 2010, 08:31 AM
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#4 |
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Inner Circle
Join Date: Feb 2006
Location: Belfast, UK
Posts: 6,158
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Most 2/3" zooms breath when adjusting focus. The Canon wide angle zooms don't breath to a noticeable extent. What can work with some shots is to use the macro for the rack focus, setting the focus ring for the distant object and pull using the macro - it's very much an eye focus job.
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March 24th, 2010, 02:50 PM
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#5 |
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Trustee
Join Date: Dec 2006
Location: Little Rock
Posts: 1,383
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Double check the back-focus adjustment on the lens.
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