by damned truths

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This is borderline off-topic really, given the stated purpose, but the short answer is that you can't as the variables that influence this are many including how many elements, the curvature of the lenses, etc. What you can determine is the size of the aperture in a simple lens situation. Assuming a 50mm lens where there is just the one element, then the ...


You would have to know the largest aperture A (lowest F number) as well. And then, theoretically, Diameter = FocalLength / A But many 'correction' factors apply due to the other elements of the lens, so this is only a first order approximation. Concrete answer: No, there is no accurate way to do this. Only a rough estimate for a given F and A is ...


I had the same exact problem. I use a 70D, and it was focusing way too far front, ruining my shoots. I was about to take it apart and solder the points, when I realized that the camera has an AF microadjustment feature. It was focusing too far forward, so I set it to +17 (out of 20) and now the lens is sharp as a tack. Definitely try this first if your ...

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