Once you've settled on the subject and the light, you have to decide on
the relative prominence of objects in the scene. By moving the camera
position back and forth, you can adjust the relative size of objects in
the scene. After you're happy with the position, you pick a camera lens whose
angle of view encompasses all the objects that you want to include in
Objects? Relative prominence? I only want to take a picture of my
friend Cyrano! There is only one object in the scene and it is Cyrano's
Au contraire! The objects in this scene are Cyrano's nose, Cyrano's
ears, and Cyrano's eyes. Suppose that you position your camera 10" from
Cyrano's eyes. If his nose sticks out 5" in front of his eyes, then it
will be only half the distance from the camera as the eyes and therefore
relatively more prominent. Stretch out your arm right now and compare
the size of your index finger to the lines of text on the monitor. Only
about as big as a paragraph, right? Now close your left eye and bring
that same finger in until it is just in front of your nose. Note that
your finger appears taller than the entire monitor.
Aesthetic tip from MIT: when your nose sticks out 5" in front of your
eyes, you don't want it to appear relatively more prominent.
Suppose that you actually want this photo as the "before" illustration
in a plastic surgeon's advertisement. Well, then haul out the 24mm wide
angle lens and you can have a complete portrait taken from 10" away.
Suppose that you wish to flatter Cyrano. You'll want to back up until
you are separated by the length of a football field. Now his nose is
still 5" closer to the camera but that is 5" out of 100 yards (note for
European readers: 100 yards is just short of half a standard furlong.)
So instead of being 50% of the distance to the camera as Cyrano's eyes,
the nose is 99.86% of the distance away. It will not be significantly
What about the 24mm lens from this camera position? It will give you a
nice photo of the entire stadium and the city behind it. Cyrano's face
will appear as a portion of a grain of silver on the film. You're now
100 yards away from Cyrano so you will need the Mother of All Telephoto
Camera Lenses. In fact, according to the formulas in my
Professional Photoguide, if Cyrano's face is 12" high, you will need
a 7500mm lens to fill the frame with it. Cyrano will be flattered but
considering that a Canon 600mm lens costs almost $10,000, the effect on
your wallet will not be a happy one.
Exactly how long a camera lens do you need?
Apologies to people from countries that have adopted sensible units.
If sensors and camera lenses were perfect... you would need only one lens!
In a perfect world, you would leave the house with only a Canon 14 super-wide lens. You would
worry only about camera position, secure in the knowledge that the
14mm lens was wide enough to capture the entire subject under 99% of
conditions. Then if you wanted a picture of just a
friend in the middle of the frame, you'd crop down to just the center and
use that. The result would be the same as if you'd used a 100mm portrait
The reason this doesn't work is that lenses and sensors aren't perfect.
If you throw away 98% of the area of the digital sensor (and/or make a
huge enlargement), you can expect to have some pretty crummy looking
pixels. So if you're sure at exposure time that you will want more
magnification, it is best to carry some higher magnification camera
The rest of this article discusses what kinds of camera lenses we might
want to lug around.
Wide angle camera lenses
With a full-frame digital SLR or 35mm film, a wide angle lens is
generally considered anything with a focal length of 35mm or less.
Here are a couple of snapshots taken with an ancient
Canon 20-35/2.8L zoom lens (replaced by
Canon EF 16-35mm f/2.8L II USM, (compare prices)). Note that the image on the left, at 20, appears to be significantly
distorted if you view it from far away. But try clicking on it so that
you get a monitor-filling JPEG. Then move your face in close to the
monitor so that you are viewing it from a few inches away. The
distortion disappears, right? A wide angle lens does not distort
perspective but, if the viewer of the ultimate image does not adjust his
viewing position, it appears to do so.
at 20 (camera closer to car)
35 (camera farther from car)
As a practical matter, most people these days aren't impressed by a
wide-angle effect until you get down to 24mm. Wide angle camera lenses
start to get expensive at 20mm ($500) and wider. So good compromises
these days are are probably a fixed 24 ($250) or a high-quality 16-35
zoom ($1500). See the Canon and Nikon system pages for an idea of what's
A "normal" or "standard" camera lens is one that produces prints with no
apparent wide angle or telephoto distortion. In other words, when
viewed at a standard distance, a print taken with a normal lens will
appear to have no unusual perspective. For a camera taking 35mm film, a
50mm lens is considered normal.
Normal lenses are easy and cheap to fabricate. A 50/1.8 costs under
$100 and will optically outperform most of the lenses in any
manufacturer's line. Furthermore, normal camera lenses allow photography in
rather low light with no flash or tripod. A yuppie with a mid-range
zoom lens has a maximum aperture of f/4. A photographer with a 50/1.8
not only saves $200 but is gathering 4 times as much light (2 f-stops).
With a standard single-lens reflex (SLR; viewing through the lens), this
makes viewing and composition easier because the viewfinder is 4 times
If you don't feel like saving $200, you can get a
50/1.4 which will
gather another factor of 2 in light. If you are a real wastrel, you can
splurge $2500 on a lens like the discontinued
Canon 50/1.0. This gathers 16 times as much light as a typical
Telephoto lenses are high-magnification devices. These are for when you
are photographing something from far away either because you want to
flatten perspective or because you are unable to approach your subject.
It is difficult and expensive to produce a high-quality telephoto lens.
In fact, only in the last couple of decades have manufacturers been able
to design really high quality 300mm and longer camera lenses.
Telephoto lenses can be useful for portraits, most often in the 85-180mm
range. Photography of large animals is facilitated by 300-600mm
lenses. Photography of birds starts with a 600mm lens and goes up from
Telephoto camera lenses that serious Canon EOS photographers buy include the following:
A teleconverter is a small lightweight intermediate optic that will
increase the magnification of a lens, while reducing its effective
aperture. So a 2X teleconverter turns a 300/2.8 into a 600/5.6. A lot
of times new photographers ask me if they can save money by buying a
teleconverter and sticking it onto their 28-70 zoom to get a 140mm
lens. Sadly, good teleconverters cost $400 or $500 and they
only work optically on expensive lenses. With a typical zoom lens,
you'll get vignetting (darkening of the corners) when using a
Teleconverters are for professionals who own expensive lenses and want
to save weight by not carrying two lenses. They are also useful
sometimes with specialized tilt-shift lenses so that you don't have to
buy these in lots of different focal lengths.
Why carry around a whole bag of fixed focal length ("prime") lenses when
you could just buy a
Tamron 28-300 zoom lens for less than $400? With a twist of a ring,
the Tamron will give you any focal length from 28mm to 300mm. The only
problem with this idea is that, sadly, the laws of physics and common
sense have not been repealed.
Photographic lenses in general are not very good. They only appear to
be good because people very seldom enlarge or closely inspect images.
Camera lenses are subject to many kinds of distortion, all of which are more
difficult to reduce in a zoom lens design. Furthermore, zoom lenses
tend to be slower (admit less light) than prime lenses. This forces the
photographer into using flash and/or a tripod.
Does that mean you shouldn't buy a zoom lens? Absolutely not. The
average Canon EOS photographer will own three beautiful zoom lenses:
Canon EF 16-35mm f/2.8L II USM, Canon EF 24-70mm f/2.8L USM (review),
Canon EF 70-200mm f/2.8L IS USM (review). These are a
great convenience for the lazy and/or pressed-for-time photographer.
However, none of these are as good as prime lenses in their focal length
range. Each of these zooms costs over $1000, so they won't help you out
if you don't like the prices of the prime lenses.
Modern digital cameras produce extremely high quality images. In
reasonable lighting conditions, the limiting factor in the quality of
your image will almost always be the lens. If you want to achieve a
good result, you must have the correct lens for the job and it must be a
high quality example of that kind of lens.
Lots of companies make high-quality lenses. Sadly, none of them have
figured out how to break physical laws and do so cheaply. So if your
creative goals require a long telephoto or very wide angle lens, prepare
to cough up the big bucks. If you are using a larger format than 35mm,
prepare to cough up the big bucks for any lens!
If you own a Canon or Nikon digital SLR, a Hasselblad medium format
camera, or any large format camera, you can rent a wide variety of
lenses in most major cities. It will definitely expand your creative
horizons without breaking you financially. Remember when using a large
or medium format camera that a given lens focal length will result in a
different perspective than on a 35mm camera. Use this table to convert.