jbl Posted July 3, 2014 Share #1 Posted July 3, 2014 Advertisement (gone after registration) I didn't know what else to title this post, sorry . If I focus on a something and then reposition the frame so the subject is not in the center of the frame, technically the plane of focus is now in front of the subject if it's in the left hand of the frame and behind the subject if it is in the right hand side of the frame. Does anyone correct for this? I'm more curious than anything. -jbl Quote Link to post Share on other sites More sharing options...
Advertisement Posted July 3, 2014 Posted July 3, 2014 Hi jbl, Take a look here Trigonometry focus. I'm sure you'll find what you were looking for!
christoph_d Posted July 3, 2014 Share #2 Posted July 3, 2014 Hi, Using film, I believe that at an aperture of 2, the depth of field covers those differences up, assuming that the image / focal planes are reasonably flat. Additionally the natural vignetting actually means that the depth of field is larger in the periphery of the image than in the center. Photographing digitally with a Noctilux wide open and scrutinizing pixels on your monitor, I presume you may see the effect that you describe. Rgds Christoph Quote Link to post Share on other sites More sharing options...
farnz Posted July 3, 2014 Share #3 Posted July 3, 2014 I didn't know what else to title this post, sorry . If I focus on a something and then reposition the frame so the subject is not in the center of the frame, technically the plane of focus is now in front of the subject if it's in the left hand of the frame and behind the subject if it is in the right hand side of the frame. Does anyone correct for this? I'm more curious than anything. -jbl The plane of focus would be behind the subject after recomposing wouldn't it? So you'd need to sway back sightly when using a very wide aperture close to the subject to keep the subject in the plane of focus. With a subject straight in front of you, imagine that the plane of focus is a large, flat board (ignoring curvature of field for convenience) with a rod from its centre to the centre of your lens. You focus by placing the 'board' in the plane of the subject's eyes, then swivelling at the hips either way to recompose will cause the board to 'travel' behind the subject's eyes won't it? Pete. Quote Link to post Share on other sites More sharing options...
tobey bilek Posted July 3, 2014 Share #4 Posted July 3, 2014 Move in a plane parellel to the plane of focus. Quote Link to post Share on other sites More sharing options...
Jeff S Posted July 3, 2014 Share #5 Posted July 3, 2014 As with most topics, there are prior discussions, as here, for one. Jeff Quote Link to post Share on other sites More sharing options...
wattsy Posted July 4, 2014 Share #6 Posted July 4, 2014 The problem with applying the theory to practice is that many lenses don't have a flat plane of focus. My favourite lens, the 35 Summilux, has a pretty barmy plane of focus that varies in shape considerably from aperture to aperture. 2 Quote Link to post Share on other sites More sharing options...
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