The minimum focusing distance of a lens is the shortest or smallest distance that you can be from your subject and still have your subject in focus. The minimum focusing distance (also called the closest focusing distance) of a lens varies from lens to lens. Lenses also have a maximum reproduction ratio which is the ratio of the size of the subject on you camera’s sensor compared to how big it is in real life. A lens that has a reproduction ratio of 1:4 means that however big something is in real life, it will be 1/4 the size on your camera’s sensor.
Macro lenses have a reproduction ratio of 1:1. This means that the object is the same size on the camera’s sensor as it is in real life. A macro lens allows you to get close and capture close up images.
Check out this video which quickly illustrates reproduction ratio and the advantage that smaller sensors have when it comes to reproduction ratio.
There are lots of different macro lenses that have a 1:1 reproduction ratio. All three of my macro lenses (60mm, 105mm and 200mm) can capture images with a 1:1 reproduction ratio. See the images below from each lens.
Minimum Focusing Distance
But not all of these macro lenses are equal. This brings us back to the minimum focusing distance of each of these macro lenses.
All three of my macro lenses have different minimum focusing distances. The minimum focusing distance of a Nikon 60mm macro is 18.5cm. The Nikon 105mm minimum focusing distance is 31.4cm and the 200mm macro is 48.8cm. These all seem like workable distances. However, the minimum focusing distance of a lens is NOT the distance from the front of the lens to the subject like some people might think.
The minimum focusing distance is actually the distance of the subject to the camera’s sensor.
Most camera bodies have a symbol of a circle with a line through it to show where the camera’s sensor is located. The minimum focusing distance is measured from this line to the subject.
When the 60mm lens is focused at its minimum focusing distance, the front of the lens is less than 4 cm away from the the subject! This might be ok for some things but it definitely makes it harder to approach insects or other living subjects. You are so close to your subject that you might cast a shadow on your subject and you can’t use your lens hood.
The 200mm lens gives your the greatest working distance from your subject and is excellent for capturing images of subjects that might move away when you get close.
Focal Length
The other thing to take into account with these different lenses is the focal length. The longer the focal length of a lens, the more compression you will have in your image. When I use a 200mm lens, objects in the background will appear larger than when I use the 60mm lens.
Look at the two images below. The one on the left was captured with the 60mm lens and the one on the right was captured with the 200mm lens. Look closely at the size of the wing on the right side of the frame. The wing is larger in the image captured with the 200mm lens. Also, the individual patterns on the wing are also larger in the image captured with the 200mm lens.
Let’s look at a closeup of the head of the butterfly. The head captured with the 60mm lens looks slightly wider than the head captured with the 200mm lens. Just like when I am capturing a portrait of a person, the a longer focal length will compress the features while the shorter focal lengths will widen the features. There is nothing bad about the head of the butterfly captured with a 60mm lens. Just be aware that there is a slight difference.
The following video further explains the ideas of how the minimum focusing distances and focal lengths of different lenses affect your macro photography.
Why 3 Macro Lenses?
Some people might ask why I have 3 macro lenses in the first place. Each of them has their own purpose.
The 60mm macro lens is a small lightweight lens that is relatively inexpensive. On a crop sensor camera, the 60mm lens is like a 90mm lens which is a nice portrait focal length. Also, I use the 60mm lens along with the Nikon ES-2 Film Digitizing Adaptor Set to digitize images I capture with my film cameras like the Nikon F6.
The Nikon 105mm macro lens is a legendary macro lens. It is a great focal length and I use it for macro images and portraits. It has Vibration Reduction (VR) and a fast Silent Wave Motor (SWM). One of the things I like about the 105mm macro compared to the 105mm F1.4 when it comes to portraits is that I can get really close to my subject. The minimum focusing distance of the 105mm F1.4 is 1 meter so I am sometimes further away than I want to be. If I could only have one macro lens, it would be the 105mm macro.
I realize that the Nikon 200mm macro lens is an older lens, but it is a fantastic lens if you are really serious about macro photography. The minimum focusing distance is really what makes it so great. It is my go to lens for skittish subjects like dragonflies.
I talk more about macro photography, minimum focusing distances and reproduction ratios in this post about capturing macro images outside your front door.
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