Macro and Depth of Field (Four Photographs)
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Many people, including myself, do not shoot true macro when we shoot insects. True macro is when the subject fills the frame at 1:1 or greater (that is the object fills the sensor or is larger than the sensor). Even with macro lenses and extension tubes I am still not at 1:1. What does concern me is the working distance between the subject and my lens, the longer the lens (e.g. 100mm) the farther away I am from the subject (100mm gives 10 or more inches of working distance) and still be able to see enough of it. Short lenses mean having to get very/very close to the subject and makes the need for artificial lighting almost inevitable. So what does this have to do with aperture? The closer you are to a subject, the more limited the depth of field (sometimes only a few millimeters) at any depth of field. Going from F4 to F11, can have a small effect on depth of field, so the temptation is to use very small aperture like F16. Photos taken at apertures above F16 can suffer from diffraction adding fuzziness to the photograph. Unless you want to focus stack (take multiple photos at different apertures and combine them later) you will want that working distance I spoke about between you and the subject. It will give you a slightly larger depth of field because of the distance. Even then the depth of field will be narrow and you will have to decide how much of your subject and background really needs to be in focus. As for these photos, they were all taken at either F13-F14 and depending on how close I was to the subject you can see what is in focus and what is not. The ant is by far the most dramatic example of depth of field and I was very close. Sometimes circumstances dictate what we can have in focus, the damselfly photo illustrates this. Most macro tutorials tell you to take your photo so that your subject is side on to get the maximum in focus. They say not to take photos face on where the back-end can go out of focus, but as you can see I don’t always ascribe to the common wisdom.