MACRO PHOTO: The classical definition is that the subject projected on the “film plane” or digital sensor is approximately the same size as the subject. Recently, it has been used in advertising as a camera that is able to focus on a subject so that when a 4×6″ print is made, the subject fills the print (or larger). I have decided that using the term “close-up” doesn’t have to explain itself like the term “macro” does. In either case, it is photography that captures more detail than we are normally used to seeing with our eyes without the aid of an optical device. Generally, the two terms are somewhat interchangeable; however, purists will go on and on about the differences between them. Semantics have always been a moot point.
Someone recently asked about extension tubes and I created a brief entry on the subject. I also wrote an article relating to DSLR exposure modes. Displayed below are image comparisons of shots made with macro lenses and extension tubes. I used a Nikon 50mm f/1.8 lens with the extension tubes for simplicity’s sake. I also took several shots using Nikon 105mm and 60mm prime lenses. The idea is to give an idea of the differences by using visual comparisons. Although this project was not an extremely controlled setup, the criteria was to get as close as I could to the subject, in this case, playing cards, and focus on them. I used several different f-stops and their related shutter speeds. The extension tubes render the aperture adjustment useless. So when taking closeup shots using the extension tubes, the only critical factors are shutter speed and focus. The shots will be explained as you scroll down the screen; however, I started with the 105mm micro lens, attached all of the extension tubes with the 50mm lens, and finally, several shots using the 60mm macro lens with various aperture openings.
This shot above shows that at an aperture opening of F/9, the top half of the image is out of focus. Using a smaller aperture like f/22 would make more of the image in focus.
As you can see in this image, stacking all of the extension tubes really gets you close to your subject. Even with good lighting (daylight corrected fluorescent), the exposure time is rather long at 1/4 of a second. A tripod and remote shutter release is necessary to remove as much movement as possible. In addition, you have to be careful to not move the camera/tripod as the focus point can be lost with only a fraction of inch of movement.
In this project, I connected a laptop to the D70 via USB and was running Nikon Camera Control software. This allows changing settings without touching the camera. In addition, I have the camera powered with an AC/Adapter charger (EH-5) which allows me to forget about battery charge life during the session.
Extension tubes have no optics. They merely create distance between the camera’s sensor and the lens. The further the lens is from the camera’s sensor, the more the lens is forced to focus much closer to the subject. Since the distance is increased as more of the tubes are added, the exposure time has to be increased to compensate for this added length.
The next image is a crop of the full sized image with no reduction. Obviously, all the other images have been reduced for browser display.
The image above was made the same as the last; however, the 36m extension tube was taken off the stack and the shutter speed was increased to 1/5 of a second.
The above image was taken with the 12mm extension tube coupled with the 50mm lens. This is the last shot using the extension tubes. Note that the depth of field is not as critical when the subject is shot head-on. This changes when shooting at an angle and across the plane.
The photo above compared to the one below show the effects of aperture size variations. The image point of focus was at the top of the card. In the photo above the aperture is set to f/9 and the foreground is out-of-focus. The 50mm lens is consider the lens that is closest to what the human eye sees.
The image above has the same setup as the previous image, but the aperture size was set to f/22 giving a greater depth of field. Noticed that the foreground is now in focus as well as the top portion of the photo.
The Nikon 60mm macro (Nikon calls it Micro) lens creates tack sharp images. This image was taken at the closest focus point that I could manage to give an idea of what a photo looks like when you move the camera and lens in as close to the subject as possible. The following images were taken at an angle to emphasize the effects of varying the aperture size - f-stop.
This photo is relatively sharp across the plane. You can see a blurring effect moving up toward the top of the image. The following images will show how the depth of field decreases as the aperture opening increases.
Notice in this final image that the depth of field is so narrow at f/8 that the queen’s nose and mouth are all that are in focus.
Depth of field will allow you to emphasize specific areas in your photograph while making others nearly indistinguishable.
As you can tell from the images, it takes a lot of setup time as well as trial and error to get good images using extension tubes. Good macro lenses are much easier to use when making close-ups. However, they are much more expensive.
The 105mm macro lens is very useful for taking photos of skittish things like insects. It also works will as a portrait lens. The 105mm macro lens can focus as close as 1 foot from the subject. The 60mm focuses as close as 1 7/8″ from the subject for 1:1 (meaning the subject is the same size on the photo sensor as it is in real life. Generally speaking, the shorter the focal length, the less expensive the lens.
The Nikon 60mm and the 105mm lenses are prime lenses. This means that they are a fixed focal length and will not “zoom”. They are also “fast lenses“. The speed of a lens is in reference to the maximum size of the opening of the iris in a lens or the minimum “f” number.  Both the 60mm and the 105mm Nikon micro lenses are considered fast lenses as they can open up to f/2.8. The Nikon 50mm f/1.8 is an even faster lens.
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