Pixiq

Many editors of my photo books press me to include the aperture and shutter speed I used to take each shot. Before digital, I could use the fact 'I never write down my exposures' as an excuse to get round this. Today, with all revealed in the metadata, this can no longer be my mantra. However, I still have the same reason for resisting this request. I was not being cagey. On the contrary, as anyone who knows me will vouch; I have always been expansive in passing on tips and hints. Quite simply, the odds of anyone else taking the same subject, with identical lighting, the same lens, magnification and ISO as I used, has to be minimal. However, I can appreciate it could be useful to know whether I selected a slow or a fast shutter speed or a large or small aperture.

So, in an attempt to remedy my past failures, I shall divulge why I used which apertures for the macro shots (all taken with a 105mm f/2.8 Micro Nikkor lens) that appear in this post. Before taking any macro shot, I look at the subject and decide what type of photo I am after. If I want an ID shot, then most of the subject within the frame will need to be in focus, so a smaller aperture, such as f/11 or f/16 on an f/32 macro lens will be appropriate. 

If, on the other hand, I want a dreamy, ethereal photo, especially of a pastel-colored flower, then I will shoot it with a wide-open aperture to achieve shallow focus. This is by no means a sloppy or easy option, since you still have to decide how to compose the shot and where to focus.    

For a third possible scenario, if I want a subject completely in focus, yet separated from the background, then I have to consider how the aperture will affect the depth of field (DOF), bearing in mind that DOF is a function of both the image size and the aperture. This is where using the DOF preview is so useful when taking static shots – such a flowers – with a tripod. I have met loads of people who abandon using the DOF preview because they cannot see anything. Sure, if you stop down to f/22, you won't see anything at all for it will be akin to walking into a black coal hole.

So forget what aperture you might use and open up the lens to its widest possible aperture. With your eye pressed to the viewfinder, gradually stop down the lens whilst depressing the preview button. You will then be able to see how more of the flower comes into focus as the lens is stopped down. Remember that with macro shots the DOF is equal on each side of the plane of focus. 

The focal length of the lens will also affect what appears in the background as the perspective changes; the longer the lens, the narrow the field of view and so it becomes easier to throw the background out of focus.