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-   -   Working distance with a close-up lens like Nikon 4T on FZ5? (https://forums.steves-digicams.com/panasonic-leica-29/working-distance-close-up-lens-like-nikon-4t-fz5-56630/)

Henrik L May 26, 2005 1:25 PM

What is the focus range at 12x zoom with a nikon 4T close-up lens or equivalent 3+ diopter?

fmoore May 26, 2005 2:31 PM

Henrik L wrote:
Quote:

What is the focus range at 12x zoom with a nikon 4T close-up lens or equivalent 3+ diopter?
Henrik - The formula is F=1/d where F is the focus (or working) distance in meters and d is the diopter power of the lens. A +1 dipoter lens would focus at 1 meter or about 39". A +3 diopter lens such as the 4t would focus at 1/3 meter or about 13". Since at lower zooms the depth of field is greater, there is a range of distances where you will obtain focus. For instance, at 6x zoom you might focus from 12-14" from the subject because the subject could be in focus at either the front end or the back end of the dof. At 12x zoom the dof is very small; maybe 5mm deep. Consequently, a little bit of movement closer or further will bring the subject in or out of focus. That is the trick to macro shots; setting the zoom where you want it for framing and then moving the camera physically closer or away to obtain optimum focus. It takes practice along with good light and a still subject. And patience.

Fred


Henrik L May 29, 2005 3:34 AM

Now I understand, thank you!


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