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Optics / Lenses / Filters Questions
How could I choose a lens according my cameras, like focal length, lens mount?
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Amy -- First -- the lens mount is determined primarily by the size of the camera's image sensor. The JIIA has developed a guide for manufacturers and users in selecting lens mounts. You should be able to find information on the AIA Vision Standards page. Second -- determine the magnification (M) you need. This is the image sensor height (or width) divided by the field-of-view height (or width). Third -- use your preferred working distance (lens to scene distance) as a good estimate of the object distance (D). Fourth -- calculate your lens' focal length (F) using the formula F = D*M/(1+M). Fifth -- find a lens with a focal distance close to what you calculated and then see if you can adjust your working distance to make it work for your need.