Macro lenses: shorter is better (often)

What is the best lens for macrophotography? In an earlier post I argued that long lenses, 100mm and more, are great for photographing small subjects that are easy to scare off, and need to be photographed from a distance. They are also handy if you want to isolate your subject from its background. But what if the goal of your photography is to showcase not only the organism itself, but also its surroundings or relationships to other animals and plants? What you need in that case is a short lens.

The two very important things that are worth knowing about lenses are that (a) their focal length determines their angle of view, and (b) their focal length is correlated with the depth of field you will be able to achieve with the lens. The general rule is that the shorter the lens the wider its field of coverage. For example, a 180mm macro lens has the angle of view of only 13°, whereas a 60mm macro lens, being 3 times shorter, will have the angle of view of 39° – three times as much. In practical terms this means that if you fill the frame with an insect, the shorter, 60mm lens will also allow you to show three times as much of the insect’s background as the long, 180mm one.

Red-eyed tree frog (Agalychnis callidryas) from Costa Rica [Nikon D1, Sigma 180mm f/3.5 APO, ambient light]

Shorter lenses are also better for achieving a greater depth of field (DOF) than longer lenses at the same aperture. DOF is more difficult to quantify than the angle of view, but a difference of just a few millimeters in the lens’ focal length can make objects that are meters away from the center of focus appear much sharper. Sometimes this can be undesirable, for example if the background is busy with ungainly twigs and branches that distract from the main subject. In such a case a longer lens is better. But if you do want to show as much of the subject’s background as possible then the shorter the lens the sharper the background will appear.

The tradeoff in using short macro lenses is the working distance, or the distance between the lens and the subject that is needed to achieve maximum magnification, which gets shorter with every millimeter subtracted from the lens’ focal length. Again, a 180mm lens will allow you to achieve its maximum magnification from a distance of about 50 cm, whereas if you use a 60mm lens then you will need to be as close as 17 cm from the subject – about one third of the distance. But as you gain practice with microphotography you will quickly discover that even the most agile, skittish insects and other small animals can be approached very closely if you show enough patience.

Red-eyed tree frog (Agalychnis callidryas) from Costa Rica [Nikon D1X, Nikkor 17-35mm f/2.8 IF-ED, fill-in flash Nikon SB-28DX]

The difference in the effect of long versus short lenses can be seen in these two photos. The first one was taken with a 180mm lens (Sigma 180mm f/3.5 APO). This lens allowed me to get a very tight portrait of the iconic Red-eyed tree frog, while the background remains unobtrusively diffused. But this image lacks context, and it could have been taken in a studio (although it was taken in the Costa Rican rainforest.) For the second photo I used a very short lens (Nikkor 17-35mm f/2.8D IF-ED; technically not a macro lens, but one that focuses close enough to be used for small natural history subjects.) Here the background of the animal is prominently displayed, making for a much more interesting, engaging portrait. There is no doubt that this photo was taken in the animal’s natural habitat, and it conveys more information about the frog’s life.

4 thoughts on “Macro lenses: shorter is better (often)

  1. I am just learning about macro photography. This helps a lot. I have a 100mm macro (Zeiss), I was thinking about buying a 200 mm macro because I am hoping to get closer. All the small insects that I have approached seemed very skittish. Also, you use 2 or 3 flashes. It looks like one flash is that ring type that fits on the end of the lens. Is that really important? Doesn’t this hurt their eyes?

  2. It is true in linear terms, the greater angle of view (60mm compared with 180mm) gives you a 3 x spread compared with the longer focal length lens. This is both vertically and horizontally so the effect is to give you 9-times the total background area… which is even better. In reality it is even more because of the trigonometry involved…and then with diagonal fisheyes even more again thanks to the curved field. Interesting to see you are using a 14mm Canon lens – what is the practical close-focus on that?

    • The 14mm Canon focuses incredibly close. According to the specs this lens focuses as close as 20.07 cm, but in my experience you will get usable shots from as close as 15 cm (if stopped down to f22.) Unfortunately, you cannot use an extension ring with this lens because the focal point moves to behind the front lens.

  3. I have been shooting with short lenses for a while and just went to the 100mm. I agree with you on needing context and I must admit that while the 100mm is likebutter, I miss my shorter lens. But those were mostly with low end point and shoot cameras. The issue is if your working with super tiny organisms…the 100mm does a better job at getting close enough. I’ve gotten great results with the Ricoh cameras, but you start losing with creatures smaller than a half inch. (although it does shoot in RAW and also has adjustable focus points).What luck have you had with micro organisms while including as much context as possible?

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