For those looking to purchase a Macro lens, here is a list of Macro lenses produced by major DSLR manufactures.
| Lens | Zoom | Reproduction Ratio | Closest Focus |
|---|---|---|---|
| Nikon AF-S DX f/2.8G | 40mm | 1:1 (life size) | 6.4in. |
| AF Nikkor f/2.8D | 60mm | 1:1 (life size) | 8.75in. |
| AF-S Nikkor f/2.8G ED | 60mm | 1:1 (life size) | 6in. |
| AF-S DX Nikkor f/3.5G ED VR | 85mm | 1:1 (life size) | 9in. |
| AF=S VR Nikkor f/2.8G IF-ED | 105mm | 1:1 (life size) | 12in. |
| AF Nikkor f/4D IF-ED | 200mm | 1:1 (life size) | 9in. |
| PC-E Nikkor f/2.8D ED | 45mm | 1:2 (half life size) | .83in. |
| PC-E Nikkor f/2.8D | 85mm | 1:2 (half life size) | 15in. |
| Nikkor f/2.8 | 55mm | 1:2 (half life size) | 9in. |
| Nikkor f/2.8 | 105mm | 1:2 (half life size) | 15.4in. |
| Canon EF Compact f/2.5 | 50mm | 1:1 (life size) | 6in. |
| Canon EF-S f/2.8 USM | 60mm | 1:1 (life size) | 8in. |
| Canon MP-E f/2.8 1-5x | 65mm | 1:1 (life size) | 7in. |
| Canon EF f/2.8 USM | 100mm | 1:1 (life size) | 5.9in |
| Canon EF f/2.8L IS USM | 100mm | 1:1 (life size) | 12in. |
| Canon EF f/3.5L USM | 180mm | 1:1 (life size) | 10in. |
35 mm equivalent magnification
35 mm equivalent magnification, or 35 mm equivalent reproduction ratio, is a measure that indicates the apparent magnification achieved with a small sensor format, or "crop sensor" digital camera compared to a 35 mm-based image enlarged to the same print size.The term is useful because many photographers are familiar with the 35 mm film format.
While a "true" macro lens is defined as a lens having a reproduction ratio of 1:1 on the film or sensor plane, with small sensor format digital cameras an actual reproduction ratio of 1:1 is rarely achieved or needed to take macro photographs. What macro photographers often care about more is simply knowing the size of the smallest object that can fill the frame.For example, the 12 megapixel Micro Four Thirds Panasonic Lumix DMC-GH1 camera with a 2x crop sensor only requires a 1:2 reproduction ratio to take a picture with the same subject size, resolution, and apparent magnification as a 12 megapixel "full-frame" Nikon D700 camera, when the images are viewed on screen or printed at the same size. Thus a Four Thirds system macro lens like the Olympus Zuiko Digital 35 mm F3.5 Macro lens with a true maximum image magnification of 1.0x is rated as having a "2.0x 35 mm equivalent magnification".
To calculate 35 mm equivalent reproduction ratio, simply multiply the actual maximum magnification of the lens by the 35 mm conversion factor, or "crop factor" of the camera. If the actual magnification and/or crop factor are unknown (such as is the case with many compact or point-and-shoot digital cameras), simply take a photograph of a mm ruler placed vertically in the frame focused at the maximum magnification distance of the lens and measure the height of the frame. Since the object height of a 1.0x magnified 35 mm film image
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is 24 mm, calculate 35 mm equivalent reproduction ratio and true reproduction ratio by using the following:
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- (35 mm equivalent reproduction ratio) = 24 / (measured height in mm)
- (True reproduction ratio) = (35mm equivalent reproduction ratio) / Crop factor.
Since digital compact camera sensor sizes come in a wide diversity of sizes and camera manufacturers rarely publish the macro reproduction ratios for these cameras, a good rule of thumb is that whenever a 24 mm vertical object just fits, or is too tall to fit in the camera viewfinder, you are taking a macro photograph.
Technical considerations
Depth of field
Limited depth of field is an important consideration in macro photography. Depth of field is extremely small when focusing on close objects. A smallaperture (high f-number) is often required to produce acceptable sharpness across a three-dimensional subject. This requires either a slow shutter speed, brilliant lighting, or a high ISO. Auxiliary lighting (such as from a flash unit), preferably a ring flash is often used (see Lighting section).
Like conventional lenses, macro lenses need light, and ideally would provide similar f/# to conventional lenses to provide similar exposure times. Macro lenses also have similar focal lengths, so the entrance pupil diameter is comparable to that of conventional lenses (e.g., a 100 mm f/2.8 lens has a 100 mm/2.8 = 35.7 mm entrance-pupil diameter). Because they focus at close subjects, the cone of light from a subject point to the entrance pupil is relatively obtuse (a relatively high subject numerical aperture to use microscopy terms), making the depth of field extraordinarily small. This makes it essential to focus critically on the most important part of the subject, as elements that are even a millimetre closer or farther from the focal plane might be noticeably blurred. Due to this, the use of a microscope stage is highly recommended for precise focus with large magnification such as photographing skin cells. Alternatively, more shots of the same subject can be made with slightly different focusing lengths and joined afterwards with specialized focus stacking software which picks out the sharpest parts of every image, artificially increasing depth of field.
Compact digital cameras and small-sensor bridge cameras have an incidental advantage in macro photography due to their inherently deeper depth of field.For instance, some popular bridge cameras produce the equivalent magnification of a 420 mm lens on 35-mm format but only use a lens of actual focal length 89 mm (1/1.8″-type CCD) or 72 mm (1/2.5″-type CCD). (See crop factor.) At the same f/#, that corresponds to an entrance pupil 89/420 = 0.21 times the size—much smaller. Since depth of field appears to decrease with the actual focal length of the lens, not the equivalent focal length, these bridge cameras can achieve the magnification of a 420 mm lens with the greater depth of field of a much shorter lens. High-quality auxiliary close-up lenses can be used to achieve the needed close focus; they function identically to reading glasses. This effect makes it possible to achieve very high quality macro photographs with relatively inexpensive equipment, since auxiliary closeup lenses are cheaper than dedicated SLR macro lenses. However, the amount of light gathered goes by the area of the entrance pupil, so with the smaller entrance pupil only 4.5% as much light is captured; alternately the full-frame camera would produce the same image by stopping down, increasing the f/# by a factor of 420/89 = 4.7 (e.g., fromf/2.8 to f/13.16).
Lighting
The problem of sufficiently and evenly lighting the subject can be difficult to overcome. Some cameras can focus on subjects so close that they touch the front of the lens. It is difficult to place a light between the camera and a subject that close, making extreme close-up photography impractical. A normal-focal-length macro lens (50 mm on a 35 mm camera) can focus so close that lighting remains difficult. To avoid this problem, many photographers use telephoto macro lenses, typically with focal lengths from about 100 to 200 mm. These are popular as they permit sufficient distance for lighting between the camera and the subject.
Ring flashes, with flash tubes arranged in a circle around the front of the lens, can be helpful in lighting at close distances.Ring lights have emerged, using white LEDs to provide a continuous light source for macro photography, however they are not as bright as a ring flash and the white balance is very cool.
Good results can also be obtained by using a flash diffuser. Homemade flash diffusers made out of white Styrofoam or plastic attached to a camera's built-in flash can also yield surprisingly good results by diffusing and softening the light, eliminating specular reflections and providing more even lighting.
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