Digital photography and the macro universe
Phil Williams (http://www.photosolve.com), May 9, 2001
You can read dozens of different articles on macro photography, but until you actually try experimenting with it, you really won’t understand the sense of awe that you get from the strange and amazing images that can result. Whether you’ve decided to practice on flowers or insects, there is a whole new macro universe that begins to open up to the camera when you take the time to just look and capture it.
If you already have a digital camera, then you’ve likely discovered how much easier it is to “waste” shots than it ever was with film. The high costs of film processing and development are limited to the cost of the digital film (whether it be CompactFlash or SmartMedia). If you don’t like the result that you just got, simply erase it. Subconsciously, I used to think about the costs of development and printing when a questionable shot would present itself. Generally, I’d let the economics drive the approach, which meant that it took much longer for my techniques to improve. Film development took hours or days before I saw the results and I might not always remember what I did to get those results. So, before we start talking about macro photography, let me stress that it’s important to take that same approach. If you don’t like the results, simply erase the picture. Practice, and try different techniques.
Most digital cameras today come equipped with a telephoto zoom built into the camera. This is helpful when you’re trying to zoom in on a scene, and focus on a central subject area. This is fine for situations where the field of view is about 4–6 feet wide, and you’re standing 8–10 feet away, but we’re going to be dealing with much smaller things that are only a few inches across or even smaller.
Moving in on the subject
Many digital cameras have a “normal” focus range that goes from about 1–2 feet out to infinity. Some offer both auto-focus and manual focus. Some have manual and automatic aperture settings. Although these factors are important, in my opinion the one most single important aspect is the ability to add lenses to the front of the camera. For a long time, camera manufacturers ignored this aspect of the digital camera world even though 35mm cameras nearly always had threads on the front of the standard lenses. The good news is that many of the newer digital cameras have threads on the front. If your digital camera doesn’t have threads on the front, or an adapter designed to mount on the camera to allow this, then you’re going to have a difficult time getting into macro photography. Check to see if your camera manufacturer offers an add-on lens adapter or if it’s available from a third party.
Using close-up lenses
This is probably the easiest and cheapest way to get into the macro world. Close-up lenses are fairly inexpensive, generally coming in sets of three or four different strengths. The term that is used to measure the strength, or magnification, is the diopter. A set of three close-up lenses generally contains a +1, +2 and +4 diopter lens. The strength of the lens will most often be marked directly on the lens. The lenses can be combined together to get different strengths. A +1 and +2 can be combined to get a +3 diopter equivalent lens. In short, a larger number represents a stronger lens. In slightly more complicated terms, each +1 in diopter strength increases the viewed size of the object by 25%. That means that a +7 combination of lenses will result in a 175% increase in size, and the object will be 2.75 times its originally viewed size. We would refer to this combination as having a magnification of 2.75X.
Because they are essentially magnifying lenses, their strength is in bending light. This causes some distortion. With more distortion appearing closer to the outside of the lens, it is generally recommended that the strongest lens be placed closest to the camera, followed by the next strongest lens, and so on. This won’t completely eliminate the distortion effect, but it will help to minimize it.
Most lens manufacturers will recommend the use of close-up lenses by setting the focus of the camera to infinity and then moving the camera closer or further away from the object to focus. I have found that you can also set the camera to the minimum focus distance (typically 1 to 1.5 feet), and have more spectacular effects, typically reducing the minimum distance to the subject by one third or more. With some of the newer digital cameras, focus is achieved with sensors measuring the distance directly through the lens as opposed to an external sensor, so it is possible to use the auto-focus of the camera in addition to moving the camera. You will still need to move the camera to get proper focus, though. Because many digital cameras are not SLR cameras, this means that in order for you to focus properly, you’ll need to use the LCD on the back to achieve focus. This can be somewhat challenging, but with some practice you’ll get good at it. If your camera is a viewfinder type camera, be aware that what you see through the viewfinder will not be what the camera sees as you move closer to an object. This effect is called parallax and you’ll have to overcome it by using the LCD.
One important point to be made here is that as you add greater magnification, the depth of field becomes very small. The depth of field is a measurement from the front of the camera to the first thing in focus to the furthest thing away from the camera that is also in focus. With high magnification, there will only be a very narrow range from the front of the camera that will actually be in focus, often as little as 1/4" or less. This is not necessarily a bad thing and can lead to some very dramatic results. If you do need a greater depth of focus, you might have to reduce the number of close-up lenses you use, and rely on the zoom of the camera.
You can also overcome this factor somewhat by using a much higher f/stop on the camera (if this is available in a manual setting). Typically values of f/16 or f/22 are necessary. With digital cameras, even this larger f/stop doesn’t overcome the problem very well since the CCD sensor in the camera is so small, and the f/stop changes have minimal effect on the focal depth. The other unfortunate side effect of increasing the f/stop is that you cut down on the amount of light entering the camera. This means that you either have to have a lot of light available or you’re going to have to increase the exposure time. If your exposure time increases above 1/30 of a second or so, you’d better plan on using a tripod. For this kind of photography, I generally recommend a tripod in any case, as it allows you to focus on composition rather than continually worrying about the focus. Remember to keep practicing – you can just “throw away” the bad shots.
A little trick that helps me find the right lens for a given distance is to use straws that have been cut to the right length for each additional diopter lens. Set up your camera indoors on a flat table and put a detailed picture in front of the camera. It also helps to have a tape measure that will allow you to measure the distance to the picture from the front of the camera. Put a +1 lens on the camera, focus and shoot. Import the picture to your computer, and check it for focus. If it looks right, then measure the distance and cut a straw to that length. Put a label on the straw and write +1 on it. Do the same for other combinations, and you’ll have a little toolbox when you’re out taking pictures.
Using close-up lenses with add-on telephoto lenses
You can get even greater magnification by adding an external lens on your camera, like the EagleEye OpticZoom 5x, and then adding close-up lenses to the front of that. If you combined a +7 diopter lens (remember, that’s 2.75x magnification) and the 5x OpticZoom, and you had a 3x zoom on your digital camera, you’d end up with 3 times 5 times 2.75, or 41.25x! For this amount of magnification, you would definitely need to use a tripod to eliminate any movement of the camera and lens combination.
Using 35mm lenses on a digital camera
I get asked all the time if a standard 35mm lens can be used as an add-on lens on a digital camera. The general answer for most digital cameras is no. The 35mm lens is designed with a focus point about an inch or so behind the back of the lens, which is the wrong place if you can’t remove the primary lens from your digital camera. There are camcorder lenses that are designed for this application, like the EagleEye OpticZoom mentioned previously.
There is a very cool old photographer’s trick (I’m never sure if that’s an old trick for photographers or just a trick for old photographers) that allows you to turn the lens around and add it to the front of your digital camera. You’ll need a special adapter called a reversing ring that has male threads on both sides. Since it’s not a common device, finding it can be a bit challenging, but a well-stocked camera outlet should be able to provide one.
Once the add-on lens has been reversed, you’ll end up with a magnification effect. For experimentation purposes, try holding the reversed lens up to your digital camera and you should immediately see the result. The actual amount of magnification will depend upon the setting of the zoom on your digital camera and the focal length of the add-on lens. If your camera lens was set to 100mm and you added a reversed 50mm lens, then the magnification would be 100/50 or 2x, the equivalent to a +4 diopter lens. Greater magnification can be achieved using different lens combinations.
I recently began experimenting with digital photography and the microscope. This is one step even further into the world of macro photography. Magnifications of 50x, 75x and more can be easily achieved, and the things you’ll discover are simply amazing. You’ll probably need a special microscope adapter to connect your digital camera to your microscope, and you’ll have to do a bit of adjusting to get things just right, but you might just never return to our everyday world once you get a few “bee’s knees”.
The macro world can be magical. I’ve hopefully hit upon a few techniques that will let you explore it on your own. Take lots of pictures along the way. Each one will bring you a bit further along in your journey.