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Author Topic: Tilt calculation  (Read 1079 times)

sharperstill

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Tilt calculation
« on: July 05, 2013, 02:26:02 AM »

Hi all,
I normally don't consider myself that stupid but I'm having trouble understanding what I should be measuring in relation to this comment "To use, simply measure or estimate the perpendicular distance from the lens
to the plane of focus" from this article http://www.davidsummerhayes.com/Focusing%20the%20tilt-shift%20lens.pdf
So, perpendicular to the lens axis I assume? To the plane of focus? A plane, by definition, take up linear space so where on that plane do I measure or estimate to?
I assume this measurement is done with the lens' tilt mechanism zeroed.
Can someone help a blind man see?

Jon
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BartvanderWolf

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Re: Tilt calculation
« Reply #1 on: July 05, 2013, 04:07:36 AM »

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== If you do what you did, you'll get what you got. ==

sharperstill

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Re: Tilt calculation
« Reply #2 on: July 05, 2013, 07:54:47 AM »

OK,
So the measurement is taken perpendicular to the lens axis to the desired plane of focus.
And the hinge line is perpendicular to the plane of focus.
« Last Edit: July 05, 2013, 07:57:19 AM by sharperstill »
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Petrus

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Re: Tilt calculation
« Reply #3 on: July 05, 2013, 08:15:32 AM »

Yes, the plane of focus, a plane perpendicular to the lens rear nodal point and the plane of the sensor/film converge always on a single line. With a non-tilt lens this is at infinity (in other words they do not converge), with a tilt lens this line gets closer to the camera and causes the plane of focus to tilt.
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michael

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Re: Tilt calculation
« Reply #4 on: July 05, 2013, 08:50:32 AM »

Do yourself a favour, unless the question is academic. Adjust for Schiemflug by eye. It will be faster and more accurate than doing it by the numbers.

If that wasn't the point; sorry, as you were.

Michael
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