Help undstanding lenses
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24-06-12, 03:04 AM
Join Date: May 2012
MM stands for millimeters. I think what your asking requires a far from basic answer and unless you own a full frame camera it gets more complicated.
How it helps you is it will allow you to work out the min distance between lens and distance in front of the lens required before light starts to focus. Or think of it as how far away you need to be before the lens can focus on a subject.
With a cropped sensor camera (which ill assume you have?) you'll also need to factor in the crop factor. For this example ill assume you have a canon camera and either have a 7D or under which means you will have a crop factor of 1.6. This means your focal lengths will need to be times by 1.6 so with a lens with a focal length of 50mm will have a true focal length of 80mm meaning the lens (which is an internal part of the whole lens) will need to be 80mm away from the subject before it can focus.
It does where it makes no never mind.
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