> On Sep 15, 2019, at 9:33 PM, P. J. Alling <[email protected]> wrote: > > The "standard" circle of confusion, for any format was calculated based on > "acceptable sharpness" results for a given print size, (which is kind of > arbitrary), for a print at standard viewing distance, but these values are > published.
I think that there is a misunderstanding here. What I was referring to was if you have a point source of light at the focal distance, it will register on the sensor/film as a point (in theory). If you move it towards the camera the light it projects on the sensor will get larger. As long as it is smaller than the CoC (in the final image) by your definition then it is in focus. Once you come closer than that, it is no longer defined as within the depth of field. The same works for moving the point source away from the focal distance as well. That basically uses a threshold on an analog function to give a boolean (in focus/out of focus) output. What I’m interested in seeing is the shape of the curve for the radius of that blur of light. Granted, in order to do that, we need to come up with some definition of the outer boundary for that blur of light since it won’t be a perfect circle of uniform brightness. My understanding is that it would end up being something like a gaussian distribution, brighter in the center and tapering off asymtopicly to zero. I suspect that the shape of the curve of the size of the blur at a distance from the focal distance would look to a zeroeth order approximation something like a parabola. I suspect that the steepness of the sides of the curve will depend either on both focal length, and distance in such a way that even at nominally the same depth of field, the way things progress to more out of focus as you get away from the focal plane, will be different with different sensor sizes/focal lengths. If the word for the size of the out of focus blur projected by that point source of light onto the sensor is not circle of confusion, I apologize. -- Larry Colen [email protected] -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
