View of the Drew | Andrew Halpern Photography

Decoding a Lens Name

Zomg, lenses have so many numbers, what do they all mean! Don’t worry, The Drew is here to solve your problems. Bear with this… I’ll explain everything.

On we go….

A typical camera lens is named according to this pattern with various deviations:

{Manufacturer} {Mount type} {Focal Length} {Max aperture} {Stabilization?} {Miscellaneous}

Let’s look at the typical kit lens that comes with many Canon cameras. The Canon EF-S 18-55mm 1:3.5-5.6 IS II.

Manufacturer

Canon

Mount type

EF-S

With current Canon lenses there are three mount types, EF, EF-S, and EF-M.

EF lenses are the most compatible. They can be used with both full-frame and cropped sensor (APS-C) Canon camera bodies.

EF-S lenses (like the one in my example) are specially designed for Canon’s smaller APS-C sensors. They cannot be used on full-frame cameras. These lenses are often either cheaper, or are available in wider focal lengths than are available on EF lenses. For ultra-wide angle type of views, the only option will be an EF-S lens.

EF-M lenses are a new type of lens specially made for Canon’s mirrorless camera system. They are the least compatible lenses and can only work with Canon’s mirrorless offerings. I don’t know much more about them.

There are a plethora of mounts available with other camera systems. Different manufacturers also use different acronyms for the lenses designed for cropped sensor cameras.

Unfortunately, I only know a little bit about other camera systems so you are on your own there. Important questions to keep in mind: Are you using a cropped sensor camera and is your camera an SLR or mirrorless design.

Focal Length

18-55mm

The focal length will be either one number or two numbers. In this case, we have two numbers so we know we have a zoom lens.

Zoom does NOT mean telephoto, it simply means variable focal length. There are ultrawide zooms, standard zooms, superzooms and telephoto zooms.

Ultrawide refers to focal lengths smaller than the view of 24mm on a full-frame system. The lens in my example is *not* ultrawide despite the wide-angle being 18mm. Why is that? Remember that with APS-C cameras we are always dealing with the 1.6x crop factor. In this case, the 18-55mm lens “acts” as if it were a 29-88mm lens on full-frame.

Standard zooms is a murkier description but it generally refers to zoom lens that start at an equivalent view anywhere from 24mm to 35mm at the wide end and progress to a short telephoto range.

Superzooms refer to lenses with zoom-factors greater than 5x. For example, an 18-200mm is a superzoom since 200/18 = 11.1x. These lenses are very convenient but the trade-off is often that they have fairly narrow maximum apertures especially at their telephoto ends. There are other optical trade-offs to be made with this design as well.

Telephoto zooms generally refer to zoom lenses where the minimum focal length is at least 70mm or higher in full-frame terms. These are often used to let you get very close to the subject if you could not otherwise. With telephoto lenses, you need a lot of light and handshake becomes an issue as small movements get magnified. Stabilization helps a lot here.

Primes

If the focal length shows only one number, the lens has a fixed focal length and is known as a prime lens. These often have very wide apertures, let a lot of light in, and are easier and cheaper to design than zoom lenses.  They come in every focal length available.

Maximum Aperture

1:3.5-5.6

This is the widest possible aperture (f number) that the lens can use at a given focal length. Remember that lower f-numbers mean *wider* apertures. The reason for that is we are dealing with denominators. Just like 1/2 is larger than 1/4, the same applies with f-numbers.

With zoom lenses, you will often see two f-numbers. The first number means the widest aperture that the wide-angle extreme can use. The second number refers to the widest aperture that the telephoto extreme uses.

Thus for this lens at 18mm I can use f/3.5, but at 55mm I can only use f/5.6. Between those focal lengths, the maximum aperture gradually gets narrower as one zooms to 55mm.

Some zoom lenses only have one aperture number, this means the maximum aperture is the same throughout the zoom range. Prime lenses will always have one number here since there is only one focal length.

Lenses with wider apertures (f/2.8 or lower) let more light into the camera, allow for blurred backgrounds, and contain more glass for a given focal length.  With zoom lenses and very long telephoto primes, things get expensive. However, at shorter focal lengths, simplified design means that prime lenses can have wide apertures and remain quite inexpensive as far as camera equipment goes. Canon makes an ultra-cheapo, yet sharp and fast 50mm f/1.8 lens that can make some beautiful shots.

Typographic standards vary. For example, you’ll see f/3.5 listed as 1:3.5 or sometimes f/3,5 or some combinations. These all mean the same thing! Be careful! A lens marked 1:2 means f/2.0 not f/1.2.

Stabilization

IS (Image Stabilized)

All other things being equal, it’s always better to have a lens with stabilization. Image stabilization reduces handshake and will let you to handhold the camera with slower shutter speeds and still have a sharp image. Even with a fast lens, stabilization will allow greater flexibility.

Unfortunately, manufacturers will use different acronyms for this. They all mean the same thing. If the lens doesn’t mention it, it doesn’t have stabilization.

Canon = IS (Image Stabilization)
Nikon = VR (Vibration Reduction)
Samsung/Panasonic = OIS (Optical Image Stabilization)
Sony = OSS (Optical SteadyShot)
Sigma = OS (Optical Stabilization)
Tamron = VC (Vibration Control)
Tokina = S (Stabilized)

Olympus = [None, camera bodies have in-body stabilization]

Miscellaneous

II — this means Mark II, Canon’s second revision of the lens.

This is a catch-all category. In my example, it has information about the revision number of the lens. Here is an incomplete list of other stuff you might see.

Focusing motor
USM/HSM Ultrasonic or high-speed motors will autofocus quicker. This is found on better quality lenses.
STM – Stepper Motors allow for quiet focusing during video. The focus is done by wire. It’s a new technology and some lenses with it are optically refined in other ways.

Macro (Macro/Micro)
Macro lenses (Nikon calls it Micro) have a very small minimum focus distance and let you get very close to jewelry, bugs, flowers etc. More expensive.

Perspective Control (TS, PC)
Tilt-shift or Perspective Control lenses allow you to correct for distortions that occur when shooting architecture. Very expensive.

Pro mark (L, Limited, *, SP, AT-X, EX, G)
Some manufacturers put a special mark on lenses designed for professionals. Canon uses “L” which stands for Luxury. These are the top-of-the-line, best performing lenses. Very expensive and usually pretty heavy.

MF : Usually refers to manual focus. Older lenses will not say this, as autofocus hadn’t been invented yet.

Other details

These are usually not included in the lens name but can be found in the specifications or on the lens itself.

Filter Size
eg.   ∅58mm

The “∅” refers to the diameter of the filters that go on the front of the lens. It is usually listed on the front of the lens.

Minimum Focusing distance macro2
eg.  0.25m/0.8ft

This information can sometimes be found on the lens barrel. The distance is preceded by either the word “Macro” (regardless whether the lens is in-fact a macro lens) or a little icon of a flower.   This describes the closest distance you can be to a subject and still be able to focus. True macro lenses will be able to focus much closer than this.

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