infinity focus

Started 2 months ago | Discussions thread
A Marcus Forum Member • Posts: 50
Re: infinity focus

Focusing on infinity is likely not a problem. You can focus on distant street lights, or mountains, or clouds, etc. As a rule of thumb, infinity is about 3000 x the diameter of the lens aperture. For a 14mm set to f/2.8, the diameter of the aperture = 14/2.8=5. Thus the aperture diameter is 5mm. Multiply that by 3000 = 15,000mm. That will be infinity for this lens. 15,000mm = about 50 feet. Therefor if you focus on an object distant, you will be set to infinity focus. Additionally you can focus on the hyperfocal distance.

Why 3000x the aperture diameter? At that distance, the aperture appears like a star, too far away and too small to be seen as a disk. In other words, a dimensionless point.

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