Macro Lens Guide
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This macro lens guide will describe the features of macro lenses and the macro lens specs that make them different from regular lenses.
We’ll also look at the various macro lens focal lengths and discuss why one of these awesome lenses may need to be in your gear bag.
Macro Lens Specs and Features
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What makes a macro lens different from other lenses? The most obvious features of macro lenses is their ultra-close focusing ability. But it’s more than the act of focusing closely that gives a macro lens its label.
Flat Field
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A macro lens is specially corrected for using ultra-close focusing distances. Most lenses have a characteristic known as curvature of field. A lens does not focus all points on exactly the same plane - there is a slight curvature to the focus plane compared to the film plane or sensor.
This phenomenon exists due to the nature of focusable optics. In regular photography with modern lens designs, this slight curve of the focused plane is covered by the depth of field inherent in most conditions. Depth of field covers what is on both sides of the lens, both the view of the scene and the projection to the film plane or sensor.
Macro focusing changes these conditions. Since depth of field is controlled by focusing distance as well as aperture and focal length, the super close-up distances of macro focusing can cause a large difference from center to edge of image sharpness.
Among the major features of macro lenses is that they have special optical correction to minimize the curvature of field into a flatter field of focus. This is especially helpful with the magnification ratios of 1:4, 1:2, 1:1, and beyond.
Which is why a “macro zoom lens” isn’t going to be as good for ultra close-up as a true macro lens. A macro zoom lens merely focuses very close, but isn’t corrected for flat field. Except for some specialty cinema zoom lenses and the amazing old (1970s vintage) Vivitar 90-180mm Flat Field Zoom, few zoom lenses have the needed corrections to be true macro lenses.
Macro Lens Specs - Reproduction Ratios
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One of the macro lens specs used for a macro lens guide is the magnification ratio, another is the minimum focus distance. Since the minimum focus distance is factored in with lens focal length, most macro lens guides will list the magnification ratio as the major macro lens specs.
You will see the ratios listed as a mathematical notation of a ratio, such as 1:2, 1:1, or 2:1. These numbers just listed correspond to half lifesize, lifesize, and twice lifesize. What this means is that if a macro lens focuses close enough to create a one-to-one lifesize image, this is referring to the size of the subject compared to the size of the image on the sensor or flm.
In other words, if we are photographing a 10mm disc on a full frame sensor, a lifesize reproduction ratio means that the size of the recorded subject on the recording medium is also 10mm. So, it corresponds to the actual size of the object used as the subject, thus “lifesize” or a 1:1 (one-to-one) reproduction ratio. Half lifesize would have a 5mm disc on the sensor, twice lifesize, 20mm, and so on.
Since the ratio refers to the size of the subject on the film or sensor, any enlargement of the image is going to increase the magnification to the end viewer. So, if we make a physical enlargement or view the image file on a large monitor, the magnification ratio is even greater.
As an example, if we take that same 10mm disc and photographed it at a lifesize ratio, then printing an 8X10 photograph will result in the disc on the print being 80mm in size. On a 16X20 enlargement, the disc would be 160mm. So, a macro lens reproduction ratio results in very large size views in physical prints or when seen on a computer monitor or TV set.
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Macro Lens Focal Lengths
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At any given reproduction ratio, the macro lens focal lengths will also determine the working distance or close focusing distance. A 50mm lens at 1:1 will have you focusing at around 6 inches, a 100mm lens will double that distance to a full foot, and a 200mm lens would be focused at 2 feet.
One thing to remember about these macro lens specs is that the focus distance is measured from the actual film plane or sensor and not the front element of the lens. So you can see where we’re going here.
If our camera is about 2 inches thick and the lens is around 3 inches long, that 6 inch focus distance for 1:1 with a 50mm lens results in the front element of the lens being only about 1 inch or less from the subject.
With many subjects, this may not matter much at all, but we are attempting macro lens use in the field as many of us landscape photographers will do, being that close to a subject will make lighting somewhat difficult and if the wind is blowing or the subject is a living creature, then keeping the subject in frame could be problematic.
Which is why longer focal focal lengths are often chosen by wildlife or nature photographers, because the subject-to-lens distance is more workable. The shorter macro lens focal lengths, though, are generally smaller, lighter, have a faster maximum aperture, and are less expensive.
Macro Lens Lighting
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Since the lens-to-subject working distances are pretty close, even with longer macro lens focal lengths, lighting can become an issue. If we put the sun behind us, just leaning into the subject for those macro reproduction ratios will affect the lighting. Also, the longer the distance from the rear element of a lens to the image sensor, the more light falls off, affecting exposure calculations.
So, several different solutions have been invented to light our macro subjects. One of the best solutions is a ring light, another is a lens-mounted flash or light bracket. A portable ring light can be mounted right on the lens or a stand-mounted ring light could be used and the lens is used inside the inner hole. Ring lights provide virtually shadowless lighting.
A lens-mounted flash bracket can also be used to provide lighting for macro images. Going this route will allow for some modelling of the light which can be very beneficial in some situations.
For these lighting solutions, we have the options of either using strobes or flash units, or we could make use of LED continuous lights. These are both good methods, with flashes having super long battery life versus continuous lighting, but continuous lighting is very predictable and it’s easy to see the results of our lighting configuration as we frame the shot.
Camera Automation for Macro
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Since the lights are very close to the subject, and also factoring in the light fall off issue of macro focusing, many photographers find using the camera exposure automation is a preferred method.
With flash use, exposure automation is good for us. As long as you are aware of what your camera automation is doing and how to control it, modern exposure automation is a very valuable tool.
One word of caution in regards to camera automation for macro lens use is to be wary of autofocus for macro focusing. While it can be useful for lesser magnification ratios, AF doesn’t work very well for many high magnification ratios. So, manual focus is often preferred. Another method is to preset your focus and use moving your body or a focus rail to get the subject in focus.
Macro Lens Guide
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What macro lens focal lengths are available for the major camera lines? There are many, since there are lenses made for both full frame format, APS-C, and MFT formats. We’ll list just a few for full frame format cameras from three top brands, Sony, Canon, and Nikon.
Canon Macro Lenses
Canon has two macro lenses for their APS-C format cameras, a 35mm f/2.8 and a 60mm f/2.8 lens, both very reasonably priced.
In full frame format, Canon macro lenses include several tilt and shift lenses, 50mm, 90mm, and 135mm, regular macro lenses in focal lengths of 100mm and 180mm, plus a special 65mm that provides ratios from 1:1 to 5:1, 1X to 5X.
A fast 35mm f/1.8 macro lens was recently introduced for the full frame mirrorless R series of EOS cameras with more sure to come.
Nikon Macro Lenses
Nikon macro lenses include the 40mm for their APS-C cameras, 55mm, 60mm, and 105mm for full frame DSLRs, 45mm and 85mm tilt and shift lenses for full frame DSLRs. For Z mount cameras, an FTZ lens adapter can be used with any of the DSLR lenses, with a fast macro prime lens rumored to be in development.
Sony Macro Lenses
Sony macro lenses include the 30mm for APS-C mirrorless cameras, 50mm and 90mm in full frame mirrorless, and 50mm and 100mm for full frame DSLR Sony cameras.
Third Party Macro Lenses
Sigma makes 50mm, 70mm, 105mm, and 150mm macro lenses, Tamron makes a 90mm, and Tokina makes a 100mm macro lens. These lenses are also superbly corrected for macro use and are as sharp as camera manufacturer lenses.
Your Next Lens - Macro!
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Your next lens may very well be one of these macro lenses. They also double as superb and very sharp prime lenses for general use, so that may make the jump into the world of macro lenses a little easier, since they are quite versatile lenses.
Hopefully this macro lens guide will help you decide. Any way you go, a specially designed macro lens is a great tool for any nature photographer.
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