(12C) Hyperfocal Distance

[Dieter]

(04-30-2018 02:56 PM)Mike (Stgt) Wrote:  Your questions reminds me Einsteins's saying "Never stop asking". I assume you do not expect me to give irrevocable answers to everything.

My questions were not addressed to you. I said that the "+ f" may be omitted and then I asked some questions to show that the simplifciation is perfectly fine if you consider the much larger tolerances in the input data and others.

(04-30-2018 02:56 PM)Mike (Stgt) Wrote:  For the average hobbyist this site could be sufficient -- until you find evident discrepancies. (BTW, it is not my site, I found it by chance).

Sure, I visited Elmar's website already years ago. We even had the one or other discussion on mathematical and photography-related details.

(04-30-2018 02:56 PM)Mike (Stgt) Wrote:  I have only one question, if you say

Quote:Personally, I have always simply calculated f²/Ac.

could you please estimate the relative error for the different possible (and impossible) reference points you all pinpointed and compare them with the error of your simplification?

The error, or better: the difference between the two equations is one focal length. In relative terms this is Ac/f which usually is < 1/f. As already noted in my previous post, this is negligible compared to the other factors: the true focal length alone can differ by several percent from the nominal value. Different reference planes (image plane? principal plane?) alone account for a difference larger than 1·f. But, Mike, why are you asking this? We both know that there is no relevant difference between the two equations. Don't we?

Dieter