Macro Photography Tips Part 1
After posting last week and planning some field shots demonstrating the whole Depth of Field issue with macro-photography it has rained for the entire weekend and as I focus on natural history subjects, was left rather lacking in material so the first post on the macro issue will be Depth of Field issues, but this will be a desk top study. I hope to produce something to see next week. To start, I am only familiar with the Nikon 105mm Macro lens (used by my butterfly photographer friend and guru Steve Woodhall, see his Field Guide to Butterflies of South Africa, published by STRUIK, for images taken through this lens and his trusty Nikon D80), the Canon 100mm f2.8 USM (my weapon of choice) and the Canon MPE-65 Macro lens (the one I want when I grow up). There are other lenses out there made by very reputable manufacturers however, not having used them, I am unable to comment. There are also a number of Macro converters, add ons and other attachments that are used but, besides my Dads 50 year old extension tubes for the EXA camera I first chased spiders around with and took macro shots on years ago, I cannot comment. So, the Canon 100 f2.8 USM is what I use. There are hundreds of posts on the web critting this lens as well as its upgrade, the 100mm f2.8 USM IS L Macro, so I shall not go into the technicalities. What is important though is the relationship between the f stop used, the distance that the subject is from the plane of the sensor and the depth of field for the particular relationship. One of the most useful pieces of information that I have found on the web is the table below :
Where, D is the focusing distance (from the sensor to the subject), ND is the near distance and FD the far distance. So it is fairly simple, have your subject at 0.35m from your sensor and an f stop of f8 and your Depth of Field is 0.349-0.347=2mm!!! Pretty shallow, that is the size of an insect such as a dragon flies eye and the rest is beginning to blur and soften up. The table is something the cut out, laminate and sleep on. It is incredibly valuable and worth putting in your camera bag and as a bookmark in your bedtime reading.