Macro Photography 101
Written by: Tiffany Joyce
Macro photography can be a confusing topic for many beginners. For one thing, almost all the lenses nowadays have the word macro printed on the barrel. Does this mean that it’s automatically a macro lens? What is a true macro lens? These are some of the topics that we will tackle in this article.
MAGNIFICATION AND REPRODUCTION RATIO
The first thing that you will need to understand when studying the subject of macro photography is magnification and reproduction ratio. These are the numbers you will find on manufacturer’s website when they discuss a lens’ macro capabilities. The two terms actually refer to the same thing and only differ on how the values are expressed. Magnification is expressed as 2x while reproduction ratio is expressed as 2:1. What do these numbers all mean?
When taking a regular photograph, the image projected into your camera’s sensor is smaller than the actual subject. Imagine taking a photo of a house and how the image can fit into your tiny sensor. Reproduction ratio is the relationship between the size of the image and the size of the subject. Let’s say you’re taking a photo of object that is 30mm high. If the image of that object projected on your sensor is 5mm high then the reproduction ratio is 1:6 (30mm divided by 5mm is equal to 6). If you want to find the magnification value given the same example, it would be 0.16x or 1/6.
True macro lenses have the ability to capture life-size images. These lenses have a reproduction ratio of 1:1 or a magnification value of 1x. Going back to our previous example, if the object is 30mm high then the image projected on your sensor is also at 30mm high. This is why true macro lenses can really show all the minute details of an object. This is also the reason why true macro lenses are extremely sharp. They have to be able to discern between the smallest details in the subject. The photo below is the Canon 100mm f/2.8 Macro USM which is a true macro lens.
NON-MACRO LENSES AND MINIMUM FOCUSING DISTANCE
The confusion about macro lenses happens because most manufacturers print the word macro or show the macro symbol on lens barrels. The word macro in these instances refers to the lens’ macro capabilities or its minimum focusing distance. The photo below is the barrel of a Canon EFS 55-250mm IS which shows the macro symbol.
This means that if you use this lens, the closest you can be to your subject is 1.1 meters or 3.6 feet. I took a photo of a bottle cap at the lens’ minimum focusing distance with the focal length at 250mm so you can see its macro capability. I also took a photo of the same bottle cap using the 100mm macro at its minimum focusing distance of 0.31 meters or 1 foot. The bottle cap has a diameter of about an inch and a half. You can see the huge difference between the two shots.
Shot with Canon EFS 55-250mm IS at 250mm
Shot with Canon EF 100mm f/2.8 Macro USM
Follow these steps to use a non-macro lens’ macro capability. First, turn off the auto-focus feature and set the lens’ focus to its minimum distance. This is usually done by rotating the focusing dial on the lens clockwise until it stops. You will now need to physically move closer or farther from the object until it is in focus. If you use the auto-focus function then you’re never really sure if you’re at the minimum focusing distance from the object.
In part 2 of this article, we will discuss depth of field, lighting, and specialist lenses in the field of macro photography. (You can read part 2 here. -Ed.)
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