Serene Life

by garik

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The ratio f/2.8 means the diameter of the entrance pupil is equal to the focal length divided by 2.8. The key thing to note about the above is that the entrance pupil is the image of the aperture stop as seen through the front of the lens, the ratio does not depend on the physical size of the aperture itself. A rear-mounted 2x teleconverter, such as you ...

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