The differences between close up, macro, and micro photography are based on image magnification. Increasing magnification moves an image from being considered a close up, to macro, and then to micro.
What is Close Up Photography?
Close up photos are taken at magnification ratios between 0.1x and 1x.
Put another way, the object being photographed would be projected onto the camera sensor at a smaller size than it actually is. This ranges from one-tenth the size of the object, to just above the actual size.
For instance, the image of the coffee beans covers was taken at a magnification ratio of 1:3 or 0.33x magnification.
This means the area shown in the photo is 3 times larger than the size of the sensor used to take the image.
What is Macro Photography?
Macro photography is taking photos at a magnification ratio between 1:1 and 10:1. An equivalent way to write that would be "magnification between 1x and 10x."
What is Micro Photography? (Micrography, Photomicrography or Photomicroscopy)
No one wants to type out micrography, photomicrography, or photomicroscopy. All three words describe taking a picture at a magnification ratio above 10:1.
Using micro as an abbreviation can cause confusion with Nikon's micro lenses. To avoid confusion, ignore what Nikon wants and call their micro lenses, macro lenses.
Why is it Called Macro Photography?
The root of the word comes from the Greek "markos," meaning large. When a macro image is printed or viewed on a screen, the object will appear to be large. More detail will be able to be seen than with the naked eye.
Macro Focusing Zoom Lenses
These are actually close up lenses. Most of these will have a maximum magnification ratio of 1:4 or 1:3 (0.25x or 0.33x). By the definition, those ratios are classified as close up photography.
Definitions are for communicating with others. Close up photography is just as enjoyable as any other form of photography. The important part is taking photos.
What is Macro on a Camera?
Macro mode allows a camera to focus closer than it normally does. The macro setting is useful for taking pictures of small things or getting detail shots.
If you want your entire subject to be in focus, make sure you have lots of light. The easiest way to achieve this is to take a photo in sunlight.
Direct sunlight will need to be diffused. A blank sheet of white paper, white packing foam, or white fabric will all work. A more robust solution is a small folding diffuser.
What is a Nikon Micro Lens?
Nikon brands their macro lenses, with "micro." A Nikon micro lens is the same as macro lenses made by other manufacturers.
This causes confusion when people want to buy a macro lens made by Nikon. By buying a Nikon micro lens, you'll be able to do macro photography.
Micro and macro photography refer to magnification as a ratio of subject size to sensor size. At a 1:1 ratio or 1x magnification, the image captured would be the same size as the camera sensor.
The Sony A7 has a sensor that is 35.8 x 23.9mm in size. In order to take an image at a 1:1 ratio (1x magnification), the area photographed would need to be 35.8 x 23.9mm in size.
Magnification ratios are based on the area of what is being photographed.
Sony A7 sensor area: 35.8mm x 23.9mm = 855.62mm^2
Taking a photo of an area 1/10 the size of the sensor will be 10x magnification, and will be considered micro photography.
Area to be photographed to be 10x: 855.62mm^2 / 10 = 85.562mm^2
The dimensions can be calculated by dividing the length and width of the sensor by the √10.
√10 = 3.1623
35.8mm / 3.1623 = 11.3209
23.9mm / 3.1623 = 7.5578
The dimensions of the area to be photographed for a micro photo would be 11.3209mm x 7.5578mm.
How to recognize the difference between micro, macro, and close up photography?
Higher levels of magnification make subjects less recognizable. A close up photo is still going to be visually identifiable.
Macro photo subjects can still be identified, but you may not have a visual reference. Think of the stamens on a flower or insect with more detail that can be seen with the naked eye.
Micro photos will not be visually identifiable. Photographers will include descriptions of the subject and image scale.