DOF is about what happens close to the plane of focus. If one eye is sharp, is the other eye sharp? Subject isolation is about what happens far from the camera. Longer focal lengths do blur the background more for the same f/stop, but have identical depth-of-field. Long lenses are good for isolate subjects precisely because they can get the whole subject sharp, while still blurring the background a lot. That, and framing - they cut off more of the background. If I have more magnification, DOF gets thinner. If you're at the same subject distance, a longer lens will have much narrower DoF simply because you have less of the subject. This is approximately a square law, meaning if you double focal length, you want to quadruple aperture. 50mm f/1.8 and 100mm f/7 will give similar DoF 10 feet from the subject. But an apples-to-apples comparison would have one 5 feet from the subject, the other 10 feet, and both would be shooting f/1.8. Thanks for any insights and God bless you! Is there an easy way to define this relationship? For instance, if I am shooting at FL 300mm f5.6, at what FL would that be roughly the same as F1.8? Am I missing anything here? I understand that Depth of Focus (DOF) is related to Focal Length (FL). Yes, there is an easy way to define the relationship between focal length and depth of field or depth of focus, but you probably mean depth of field. You calculate the near distance and far distance and subtract. If you want to use this formula in Excel or other spreadsheet, you need to make sure the aperture values (N) are correct. As you can see you have focal length of the lens (f), distance to subject, or focus plane, (Do), f-number (N), and the circle of confusion (c). The values are pretty straight forward but for setting c. ![]() The common values to use is 0.03 mm for FF and 0.02 mm for APS-C, although some use 1/1500th the sensor diagonal, some 1/1750th the diagonal of the sensor, and some use the size of the individual pixels. ![]() Many programs both for mobile use and on the web to have these values calculated for you. ![]() I like pCAM for iOS as it has lots of other features, but it is not cheap.ĭo a web search for Nasse, depth of field and Zeiss. You will fine a good white paper that goes into all the details for you of not only depth of field but also bokeh.I can't get this bloody controller working. I just want to use it to play with lights until my falcon comes.
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