Tilt calculation

[sharperstill]

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

[Bart_van_der_Wolf]

Can someone help a blind man see?

Hi Jon,

http://www.northlight-images.co.uk/article_pages/using_tilt.html#

Cheers,
Bart

[sharperstill]

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.

[Petrus]

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.

[michael]

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