November 19, 2017, 07:17:58 PM

Author Topic: Focus and recompose related question  (Read 9172 times)

neuroanatomist

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Re: Focus and recompose related question
« Reply #15 on: May 27, 2013, 07:21:41 AM »
This Guys red line/green line theory is correct, but focus the intended area first i.e. her face and then recompose to include the dress. Result pin sharp where you want it to be on her face with the dress slightly out of focus. In other words put the cart before the horse.

Might want to re-read that article. Your 'method' is exactly what he's demonstrating.  Focusing on the eyes is the red line, recomposing to include the dress is the green line. Result eyes slightly out of focus, dress pin sharp. In other words, your suggestion is why focus recompose sucks.
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Re: Focus and recompose related question
« Reply #15 on: May 27, 2013, 07:21:41 AM »

adhocphotographer

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Re: Focus and recompose related question
« Reply #16 on: May 27, 2013, 07:25:50 AM »
Thanks for the info all, i never thought about this...  I will certainly not F&R during portraits.
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sanj

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Re: Focus and recompose related question
« Reply #17 on: May 27, 2013, 08:07:47 AM »
This Guys red line/green line theory is correct, but focus the intended area first i.e. her face and then recompose to include the dress. Result pin sharp where you want it to be on her face with the dress slightly out of focus. In other words put the cart before the horse.

I checked several times but there were no horses or carts or cowboys in the article. :(

sanj

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Re: Focus and recompose related question
« Reply #18 on: May 27, 2013, 08:09:00 AM »
And the example is of a camera on tripod. When handholding the movement of the photographer compounds the problem am sure..

rpt

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Re: Focus and recompose related question
« Reply #19 on: May 27, 2013, 10:03:53 AM »
Ting! well looks like the penny finally dropped :D

So I read a few more articles and all of them refer to a plane of focus. So here is my new (and hopefully correct) understanding. The lens is shaped such that the focus of an image on the sensor or film is done for a plane parallel to the plane of the receptor. Thus the focusing distance indicated by the lens is the perpendicular distances between the two planes. See, that was my problem - I always thought that things would be in focus on an arc whose radius was the focusing distance. So in that case F&R would have worked - and it did for me from '67 till 2000 as most of my outputs were either contact print of 120 film or 5 by 3 or 6 by 4 prints.

Neuro, thanks for persisting :)

Others, thanks for the inputs.

So I had better learn how to do back button focus and selecting the appropriate AF point...

neuroanatomist

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Re: Focus and recompose related question
« Reply #20 on: May 27, 2013, 11:47:12 AM »
The lens is shaped such that the focus of an image on the sensor or film is done for a plane parallel to the plane of the receptor.

Correct - the lens is designed to project a flat image onto the image plane.  However, not all lenses are perfect - when a lens doesn't project a flat image, it's called field curvature.  The 24-70/2.8L (MkI) has that problem.
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Re: Focus and recompose related question
« Reply #20 on: May 27, 2013, 11:47:12 AM »