Originally posted by olenl well there ought to be an optical center so we might spot it somehow
while that may be true, without a purpose, this is doing the calculation for the point of calculation
Quote: and I don't align anything, I just solve certain system of equations ...
if yo are not making any allignment, and only solving equations, to me, it sounds like there is no need to know the center, unless of course, your equations are approaching infinity sith a divide by zero error
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focal length is just a part of the analytical formula of "ideal" projection which we know is never actually corresponds to real lens...
and your point is?
Quote: the real mapping is a table function with interpolation between measured values.
?????
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sure, that is the point. since there is no standard, we need to measure each particular instrument's properties.
No, yoou mis understand, you are talking about using the camera as a system, where individual parts are made to tolorances known only to the manufacturer's, except the lenses which have some international standard associated with the testing, and marking, but which has very wider tolorances.
When I say there is no standard, what I mean is that any measurements you make, implying the type of precision you are discussing, would require calibration to a known international test method (that does not exist) and calibration of the instrument against physical standards to a tracable (assume length) nationally calibrated measurement device.
However, having said that, if yoou want to locate the center of a sensor, I suggest you use star trails, or an array of relitively distant lights and rotate the camera in a circular manner.
The circular trails left on the film, should describe circles. regardless of whether they are offset or not, you should be able to calculate the distance each circle is offset from the center of the frame, in the X and y distance, simply by looking at the coordinates of the circles