Don’t Overlook the Small Stuff – How To Achieve Great Macro Photos by Rick Sheremeta |
The often used cliché “it’s a small world” is the very essence of macro photography – where the minute takes center stage and appears larger than life. Macro, taken from the Greek word meaning large, is defined in photography as an image that appears on the camera focal plane equal to or greater than the subject’s size in real life. Without over simplifying things or getting into the physics of lens design, it basically boils down to having the ability to get as close as possible to a subject in order to obtain an image at life size or larger while still being able to focus the lens. Most camera lenses, will typically focus anywhere from 1/10X down to about 1/4X magnification. Using 35mm format to illustrate this point means that, at 1/10X and 1/4X, an area of approximately 10” by 15”, and 4” by 6” respectively will completely fill a 35mm frame. The new AF 18-200mm F/3.5-6.3 XR Di II Macro lens provides 1:3.7 and can focus as close as 17.7” throughout the entire focal range. While “macro lenses” allow you to get fairly close to your subject, they’re not quite close enough to allow for frame filling images of very small objects. So how does one accomplish life size close-up images at magnifications of 1:1 or even greater? There are several ways in which this can be accomplished. The first way to beef up magnification is to use a dedicated 1:1 macro lens such as the Tamron SP AF 90mm F/2.8 Di or the SP AF 180mm F/3.5 DI. Both of these lenses will reproduce an image to life size and have fast apertures. The second choice is to add a supplemental lens, referred to as a close-up filter, or “plus diopter”, to your main lens. These close-up lenses are available from many of the leading camera and lens manufacturers and come in different strengths, which are measured in diopters; they are typically available as +1, +2, or +3 diopter – the higher the number, the greater the magnification. These lenses simply screw onto the filter threads at the end of your primary lens - thus the name “close-up filter”. The main advantage to their use is that there is no loss of light resulting when they are attached to the end of another lens; however, with the addition of more glass, you may experience a slight degradation in image quality. To this end, double element diopters are preferable to single element ones. But keep in mind that they will never have the same high quality glass as your primary lens. From a practical standpoint, the greatest limitation to close-up filters, is that magnification will still be directly related to the focal length of the primary lens. Thus, attaching a +3 diopter to a 30mm lens would result in 0.9X magnification; to gain greater magnification, a longer focal length primary lens would be needed. Well, you say that’s simple – why not just use a higher power diopter or stack more diopters onto your primary lens to achieve greater magnification? This sounds like a logical solution; however, there is a significant degradation in image quality as diopter power increases over +3, or with each supplementary lens that is added. The practical limit is two diopter lenses attached to the primary lens. This then leads us to the third choice, as was stated at the beginning, the closer you can get to your subject, the larger the amount of magnification that can be achieved with a lens of any given focal length. Unfortunately however, every lens has a minimum focusing distance - what this means is that the lens will just not focus if it is moved closer to the subject than this distance. It is possible however to decrease this minimum focusing distance by moving the lens farther away from the camera’s focusing or film plane. How do you accomplish this you say? There are a couple of options available. Some camera systems have extension bellows that can provide an almost infinitely variable amount of extension when attached between the lens and camera body. While this sounds great, on the surface, it is limited by practical considerations. First of all, bellows extensions are not readily available for many 35mm camera systems; especially the newer auto focus models. Furthermore, bellows are relatively delicate and, while they work great on large format cameras in the controlled studio environment, they are just not well suited to use in the field. Extension tubes provide a practical, cost effective solution that won’t overburden either your gear bag or your pocketbook. They are nothing more than hollow cylinders that are inserted between your favorite lens and camera body. Extension tubes are generally available for most popular camera mounts and come in a set of three rings of varying sizes that can be used individually or stacked in any desired combination. The amount of magnification, to be obtained with extension, is directly proportional to the ratio of extension length to that of the focal length of the primary lens. Thus, 25mm of extension used in conjunction with a 25mm lens will yield a 1:1 ratio or a life-size magnification of 1X. In selecting your lens and the amount of extension to be used, remember that as the focal length of the lens decreases, the closer the lens must be to the subject matter, to obtain the same amount of relative magnification. Therefore with a very wide angle lens you will need to virtually get on top of your subject to obtain anything close to a life size image. Although these figures may vary from one camera system to another, the following generalization will help illustrate the point that as focal length increases so too does the working distance at which a given amount of magnification can be achieved. For example, with a 28mm lens it is necessary to move within approximately ½” of the subject in order to achieve 1X magnification. This can obviously pose some problems – not only will the lens obstruct lighting the subject, and if the subject happens to be live, it will hardly stand still while its personal space is being so rudely violated. By increasing the lens focal length to 75mm, the same amount of magnification can be had at a less intrusive working distance of about 4-1/2” from the subject. Therefore, when trying to achieve close-up images, that approach life size, consider the use of a telephoto lens, which will allow a more comfortable separation between the camera and your subject. Keeping in mind these physical constraints, a telephoto zoom lens affords the greatest amount of flexibility for close-up photography. For example, with a lightweight lens such as the Tamron 28-300mm f/3.5-6.3 XR Di Macro, it is possible to set the camera at a comfortable working distance and then zoom in/or out to obtain the needed magnification. This lens provides a 1:2.9 Magnification Ratio as it allows for a 19.3” M.F.D throughout the entire focal range. The biggest drawback, to the use of extension tubes, is loss of light, which increases as the distance between primary lens and camera increases. Since macro photography requires a good steady tripod, slower shutter speeds may not be of concern, and in some instances it may even be desirable in order to achieve certain effects. With cameras that feature through the lens (TTL) metering, there is no guess work for proper exposure. Those who use older systems, which rely on manual metering, will need to rely on a fairly simple formula, or use of a table, to adjust for exposure compensation. The formula is included here for reference:
The only thing that limits the amount of, or number of extension tubes that can be combined, other than loss of light, is the physical limitation that is imposed by the weight of the lens that needs to be supported by the tube(s). The lens should be used in manual focus mode. Once the camera is set at the desired distance from the subject (you’ll need to play with this a little), use the manual focusing adjustment ring to focus. For real super fine tuning, a macro focusing rail really helps. Tele-converters can also be used to achieve greater magnification. They can be used with the primary lens alone or in addition to extension tube(s). When used with extension tubes, place the tele-converter between the camera body and extension tube. The increase in magnification is directly proportional to the size of teleconverter used - for example, a 1.4X teleconverter will increase the magnification by a factor of 1.4. Again, additional loss of light will occur when attaching a tele-converter. If things get too dark to see through the lens, a flashlight to illuminate the subject will help. Another way to achieve a relatively great amount of magnification, that you may wish to experiment with, is to stack two lenses together. With this system, the larger of the two lenses (the primary lens) is connected directly to the camera and the secondary, or stacked lens, is mounted, in reverse to the end of the primary lens. This is a great way to utilize that old 50mm manual focus lens that probably hasn’t been out of your gear bag in years. Mounting the lenses together is relatively easy with the use of a “macro-coupling adapter ring”. These rings have male filter threads on each end, and are available in most common filter sizes including those with different size threads. When mounting the secondary, or stacked lens, it should be set wide open to its largest aperture. The amount of magnification to be gained, with this system, is directly proportional to the focal length of the primary lens to that of the stacked lens. For example, placing a 50mm lens onto a 200mm will yield a 4X magnification, which is about the practical limit for conventional photographic equipment. To put this in perspective, at a magnification of 4X you could take a portrait shot of a mosquito – if you could get it to hold steady long enough. There is no loss of light with this system, unlike that which occurs with the use of extension tubes. The main limitations, to stacked lenses, are that as the amount of magnification increases, so too does the focusing distance decrease, and the shallower that the depth of field becomes. In the world of macro photography, depth of field is in the order of fractions of an inch. The first thing that you will need, to insure that images are clear and crisp, is a strong sturdy tripod that will hold the camera steady. Set exposure to manual mode and always shoot at the smallest possible aperture – adjust shutter speed to achieve proper exposure and don’t be afraid to bracket shots – the results may be most surprising. As noted previously, a macro focusing rail can really help to zero in on a very small subject area. Use the lowest possible ISO film or digital rating to minimize the effects of grain or digital noise which will also appear magnified. The combination of low film speed and small apertures will result in relatively long shutter speeds (another reason for a good sturdy tripod). Use of mirror lock-up (if you have that feature) and a cable or electronic shutter release will help in keeping any camera vibration to an absolute minimum at long shutter speeds. Photography is all about light – take advantage of this - experiment and get creative. If you don’t have studio lighting available, try shooting in front of a window on an overcast day or in front of a window with a northern exposure. This will provide good overall background lighting and color saturation for your subject. Use of reflectors, either alone or in combination with flash, will help bounce light into shadowy areas. Speaking of flash – you will need to get a flash extension cord in order to use your normal shoe mounted unit off the camera. The extension cord will provide the flexibility to backlight or sidelight the subject and bring out more detail. Several camera manufacturers make dedicated ring lights dedicated for use with their camera bodies that are specifically for close-up and macro photography. Ring lights will provide a more uniform subject lighting as opposed to directional lighting from a hand held flash unit. Before we leave lighting – try out that flashlight you used earlier to help you focus. You can use it to provide pinpoint highlighting or to just paint a warm wash of light over the subject with exciting results. The real neat thing is that you can see the effect through the camera before you take the shot. Great close-up results can be achieved utilizing any of the methods outlined in this article, experiment and find out what works best for you. Macro work presents infinite creative photographic possibilities that are limited only by your imagination. To learn more about Rick visit his website at www.alpenglowproductions.com |
 Hand held electronic flash - AF17-35 w/20mm extension; 5.0 sec. @ f/29 |
 Available light - AF17-35 w/ 20mm extension; 5.0 sec. @ f/29 |
 Available light - AF11-18 w/ 12mm extension tube: 0.8 sec. @ f/29 |
 Painted with flashlight - AF11-18 w/ 12mm extension tube; 0.8 sec. @ f/29 |
 Painted with flashlight - AF11-18 w/ 12mm extension tube; 2.0 sec. @ f/25 |
 Painted with flashlight - AF28-300 w/ 68mm extension & 1.4X teleconverter |
 Hand held flash - AF28-300 w/ 68mm extension & 1.4X teleconverter |