One of the attributes of a lens that is sometimes overlooked is its minimum focusing distance. There are many important factors to consider when investing in a new lens such as focal length, aperture, lens construction/weatherproofing, sharpness and colour rendition. So, it is not surprising that minimum focusing distance is sometimes not given much consideration.
NOTE: Click on images to enlarge.
If a photographer does a lot of close up work, or intends to use extension tubes with specific lenses, considering the minimum focusing distance is important.
It can also be an important factor when using long telephoto lenses for nature and bird photography. Often subjects may be positioned inside the minimum focusing distance of the telephoto lens being used. In many cases the photographer would then have to back away from the subject, or simply miss their shot.
We recently added three M.Zuiko lenses to our Olympus kit. Whenever I buy a new lens I always take some time to do some hands on tests pertaining to minimum focusing distance. This article shares some quick test images that I did with each lens fully extended.
All of the photographs in this article were shot handheld (my preferred shooting style) to help determine how each lens could be used when fully extended with close-up subjects. With each photograph I moved in as close as possible with my lens fully extended until it would not auto-focus. Then I slowly moved back a tiny bit until it would auto-focus and I could capture my image.
Our first sample image was captured using the M.Zuiko PRO 12-40 mm f/2.8 zoom. As you see, I was able to get in quite close to the subject. The 200 mm (~7.9 inches) distance to subject is suitable for flowers and still life subjects. When photographing insects or animals that my sting or bite, this distance is often not very practical.
When this lens is used with a 16 mm extension tube it focuses so closely on a subject that the lens can block light from reaching the subject or cast a shadow on it. As a result I don’t use this lens with extension tubes.
The M.Zuiko 14-150 mm f/4-5.6 II was used to capture the sample image above. You can see that the distance to subject was 500 mm (~19.7 inches). This allows a photographer to achieve a reasonable degree of subject magnification without being too distant from it.
The photograph above was taken with the M.Zuiko 75-300 mm f/4.8-6.7 II. You’ll note that I had to use an aperture of f/6.7 when this lens is fully extended. The distance to subject of 1.4 metres (~4.6 feet) was almost three times further than was the case with the M.Zuiko 14-150 mm f/4-5.6 II.
Our sample image above was captured with the M.Zuiko PRO 12-100 f/4 IS with a distance to subject of 450 mm (~17.7 inches). You’ll notice that there isn’t very much difference in subject size in this image to the one captured with the M.Zuiko 14-150 mm f/4-5.6 II.
The sample image above was taken with an M.Zuiko PRO 40-150 mm f/2.8 with a distance to subject of about 700 mm. Even though this lens has a longer focal length than the M.Zuiko PRO 12-100 f/4 IS, the subject is close to the same size in the frame. That’s because the distance to subject measurements are quite different, i.e. 700 mm vs 450 mm (~27.6 vs 17.7 inches).
Compare the distance to subject measurements between each of the lenses, and the size of the subject in each photograph. It is easy to see why understanding the minimum focusing distance of a lens can be an important issue.
Imagine yourself on a park bench and having a rare butterfly land next to you about 475 mm (~18.7 inches) away. Assuming that you have no room to move away from the butterfly, and you have to photograph it immediately, only two of the five lenses noted in this article would be able to acquire focus on it when fully extended.
Minimum focusing distance can be a significant issue when using long telephoto lenses. It is common for the minimum focusing distance of a 150-600 mm or a 200-600 mm full frame zoom lens to be in the 2.2 to 2.8 metre (~7.2 to 9.2 feet) range. Prime full frame long telephoto lenses can have even longer minimum focusing distances.
Unless we understand how our lenses perform in terms of their minimum focusing distance, we can inadvertently move in too close to our subject and miss our shot.
In situations where we are using a long telephoto zoom lens we still may be able to capture our image. To do this we may have to zoom to a wider angle focal length and settle for a photograph where the subject is much smaller in the frame than we would have liked.
When I used to shoot with full frame camera equipment and a 150-600 mm zoom lens, I started carrying extension tubes with me just in case I needed to shorten the minimum focusing distance of my lens.
From time to time I still do that today when using my Nikon 1 or Olympus kit. It’s like having a bit of insurance in your camera bag. The image above is an example of using an extension tube to change the minimum focusing distance of a lens.
It is important to do some testing with your lenses before using extension tubes with them when they are fully extended and shot at their minimum focusing distance. Don’t assume that a lens that performs well when fully extended at its minimum focusing distance will also perform this way when an extension tube is used.
Many modern lenses have ‘floating elements’ in them that change position within the lens to help achieve focus on a close subject. Using an extension tube can sometimes cause image quality issues when a lens is used fully extended at its minimum focusing distance. We can see a clear example of this extension tube issue with the photograph above that was captured with an M.Zuiko PRO 12-100 f/4 IS zoom when it was fully extended at its minimum focusing distance.
Photographs were captured hand-held using camera gear as noted in the EXIF data. Images were produced from RAW files using my standard process. All photographs are displayed as 100% captures without any cropping.
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