Special lenses

Learning goal

You will be able to recognize three kinds of lens designed for particular jobs that everyday lenses can't do, and judge which one is useful for which job. You will explain why a fisheye lens accepts bending straight lines for a very wide angle; you will see that a macro lens can form a small subject on the sensor at its real size, and what working distance and a slice of sharpness measured in millimeters mean; you will tell apart how tilt-shift lenses manage vertical lines with shift and the plane of focus with tilt; you will know how you can roughly do some of these jobs with cheaper tools or with software; and when coming close to a person's face or hands in close-up, you will think, on every skin, about what consent and texture mean.

The question

You are spending a single day in a small town. In the morning, when you photograph the clock tower in the square from below, the tower seems to lean backward, its edges coming closer to each other toward the top. At noon, in a tiny tailor's shop, you want to see the old tailor at their table and the whole shop in a single frame, but none of your lenses sees this wide. In the evening, when you want to come close to the thimble on the tailor's finger and the eye of the needle, your lens can't find sharpness.

What are fisheye, macro and tilt-shift for? Each of these three questions has its own lens: lenses that see very wide, that focus very close, and whose body can tilt and slide. In this lesson we will talk about these special lenses, what they do and how, and in which job each of them is really needed.

Context

On the body of the lens at the flea market we read a magnification ratio and a minimum focus distance; in the inn's courtyard frame, too, we saw the pillars bulging. Special lenses deliberately take one or more of these properties to the extreme. A fisheye accepts bulging not as a flaw but as a design choice; a macro lens makes the minimum focus distance extremely short; a tilt-shift lens lets you change the relationship between lens and sensor by hand.

Most of these lenses aren't used every day in everyday photography. But in particular jobs, in architecture, nature, product photography or cramped interiors, they give a result no other tool can give. Knowing what they do lets you decide whether you really need one.

Simple explanation

What does a fisheye do?

Everyday wide-angle lenses try to keep straight lines straight. This gets harder and harder as the angle of view grows, and objects stretch at the edges. A fisheye lens chooses another way: it gives up keeping lines straight, and in return sees a very wide angle, sometimes approaching a hundred and eighty degrees. Lines passing through the middle of the frame stay straight, but every straight line moving away from the middle curves outward like an arc.

This curving gives the fisheye an easily recognized look: the horizon bends like the edge of a planet, and a small room turns into a big sphere. It is useful in narrow interiors, in action sports, or when you want to see the whole sky in a single frame. When photographing people, though, it needs care: a face falling at the edge of the frame, light or dark, bends noticeably. Keeping the person near the middle of the frame keeps the shape of the face. Because the fisheye's look is strong, when it is used often the lens itself can be noticed more than the subject of the photo; this needs to be done as a choice.

What does a macro lens do?

A macro lens is designed to come very close to a small subject and form it large on the sensor. A true macro lens usually reaches a 1:1 magnification ratio: an insect's eye, the dimples of a thimble or the eye of a needle is formed on the sensor at its real size. Most everyday lenses can't focus this close.

Two things stand out in macro. Working distance is the gap between the lens's front glass and the subject; macro lenses with a longer focal length let you work from farther away from the subject at the same magnification, which means not scaring off a shy insect, or making room to put light on the subject. The slice of sharpness, on the other hand, is measured in millimeters at this closeness; many photographers stop the aperture down to around f/8 or f/11 in macro and build sharpness by moving the body back and forth. If you don't have a macro lens, close-up lenses screwed onto the front of the lens, or extension tubes placed between the lens and the body, can give a similar closeness, with lower quality or a narrower range of use.

What does tilt-shift do?

The body of a tilt-shift lens can make two separate movements. In shift, the optical part of the lens slides up, down or sideways while staying parallel to the sensor. When you tilt the camera up to photograph a building from below, the vertical lines come closer to each other and the building seems to lean back; with shift, though, you keep the camera parallel to the ground and only slide the lens up, and while the top of the building enters the frame, the vertical lines stay parallel. This is the main reason architectural photographers turn to these lenses.

In tilt, on the other hand, the lens tips slightly relative to the sensor, and with it the plane of focus tips too. Normally the plane of focus is parallel to the sensor; when it is tipped, for example laid down toward the ground, a stretch of ground running from the flowers in front to the distant mountains can be kept sharp even at a wide aperture. When tipped the opposite way, the plane of focus turns into a very thin strip, and a city view can look like a toy model. Tilt-shift lenses are usually expensive and most focus by hand. The vertical-line correction of shift can be approached with the perspective correction in editing programs; but this correction crops part of the image and spends some resolution.

What should you think about in close-up?

Macro and close-up let you come closer to a person's eye, eyelashes or hands than anyone looks at an everyday distance. This closeness makes asking that person's permission more important than ever: such a magnified view of a face or a hand is a decision about how that person wants to show themselves.

At this closeness the skin's texture becomes very distinct too. As we saw in Lesson 11.6, side light raises pores and wrinkles; in macro, this texture fills the frame. On light skin fine veins and spots come forward, and on dark skin small glints reflecting the light and the folds of the texture. Showing this or calming it with soft light is a choice made according to what the photo wants to tell and the consent of the person photographed.

Visual evidence

You go back to the day in the town. In the square, with the tilt-shift lens a friend lent you, you keep the camera parallel to the ground and slide the lens up; the top of the clock tower enters the frame and its edges rise straight and parallel to each other. In the tailor's shop, with the fisheye, you take the dark-skinned old tailor, glasses on the tip of their nose, into the exact middle of the frame; the rolls of fabric on the ceiling, the scissors on the wall and the street outside the door curve and fit inside a single sphere, but because the tailor's face is in the middle, it keeps its usual shape.

In the evening, with the tailor's permission, you come close to the thimble with the macro lens. At f/11, moving the body millimeter by millimeter, you put sharpness on the dimples of the thimble. In the frame, the brass dimples of the thimble, the red thread passing through the eye of the needle, and the deep creases on the tailor's fingertip, skin hardened by needle pricks, are sharp; the nail a few millimeters behind is already soft. Three separate jobs, three separate lenses; each one did something an everyday lens can't.

Common mistakes

Summary

Special lenses take one property to the extreme for particular jobs: a fisheye accepts bending straight lines to see an angle approaching a hundred and eighty degrees, and wants faces in the middle of the frame; a macro lens reaches 1:1 magnification and works with a working distance and a slice of sharpness measured in millimeters; a tilt-shift lens keeps vertical lines parallel with shift and manages the plane of focus with tilt. Some jobs can be done roughly with close-up lenses, extension tubes or perspective correction; in close-up, coming close to a person's face and hands requires thinking consciously about consent and texture on every skin.

Mini assignment

In this assignment you will approach the jobs special lenses do with the tools you have.

1. Photograph a building from below, first tilting the camera up, then keeping the camera parallel to the ground and stepping back; compare the vertical lines and try perspective correction in the editing program.
2. Photograph a small object at your lens's minimum focus distance; repeat with a close-up lens or an extension tube if you have one.
3. Photograph a small object at your lens's widest opening and at f/11, focusing by moving the body back and forth, and compare the slice of sharpness.
4. With their permission, photograph someone's hands or eye up close, first with side light, then with soft light.

Check yourself

• When you kept the camera parallel to the ground, did the building's verticals stay parallel?
• At f/11 and moving the body, did you see that the slice of sharpness is measured in millimeters?
• On the hand or eye you photographed up close, regardless of skin tone, were you able to make a conscious choice about showing or softening the texture?

Glossary

Mini quiz

1. On a fisheye lens, what happens to straight lines that don't pass through the middle of the frame?

• A) They stay straight
• B) They disappear
• C) They change color
• D) They curve outward like an arc

2. Why might a macro model with a longer focal length be preferred?

• A) Because at the same magnification it allows working from farther from the subject, that is, a wider working distance
• B) Because it sees a wider angle
• C) Because it removes the slice of sharpness
• D) Because it corrects the white balance

3. When photographing a clock tower from below, which movement of a tilt-shift lens is used to keep the vertical lines parallel?

• A) Tilt
• B) Shift
• C) Zoom
• D) Manual focus

4. What do you think about before photographing someone's hand up close with a macro lens?

• A) Only the aperture
• B) Only the white balance
• C) The person's permission, and the choice between showing and softening the skin's texture
• D) The filter diameter

Answers

1. D — A fisheye gives up keeping lines straight for a very wide angle; straight lines far from the middle curve.
2. A — A long-focal-length macro lets you stand farther away at the same magnification; room is made for shy subjects and for light.
3. B — In shift the camera stays parallel to the ground and the lens slides up; the verticals don't come closer together.
4. C — Photographing a person this close needs their consent; how much of the texture filling the frame will show is decided together too, on every skin.

Summary card

• Fisheye: an angle near a hundred and eighty degrees, bending lines; keep the face in the middle.
• Macro: 1:1 magnification, working distance, millimeter-thin sharpness; f/8–f/11 and move the body.
• Tilt-shift: shift keeps verticals straight, tilt tips the plane of focus.
• Close-up lenses, extension tubes and perspective correction are rough ways.
• In close-up, on every skin, permission and texture are a conscious choice.

Bridge to the next lesson

At the end of the day in the town you used three different special lenses; but most photographers have none of these in their bag. The real question is much simpler: what should you get second, next to the lens that came with the camera? A wider angle, a longer telephoto, a brighter prime? Which should your second lens be? The next lesson talks about choosing a lens according to what you photograph and your budget, and what place secondhand lenses can take in this decision.