Know Your Numbers and Letters: Lens Explanations

For those of you who are new to the world of lenses, or have just recently started wearing them, it can be tough to know exactly what all the numbers and letters mean. There are so many different types of lenses that offer a variety of benefits depending on your needs. Whether you need glasses for reading, sport activities, or something in between- there’s a lens type for you! In this blog post, we’ll break down some common lens types and their meanings.

lens numbers

F Numbers Mean Aperture

Focal Length and F number both represent an Aperture setting. This is the amount of light that gets into your camera to expose on your sensor or film, respectively. The lower the F-stop (or f/number) will be more “light sensitive.” this means you can shoot in dimly lit areas like indoors without a flash with less graininess than if you were shooting outdoors on a sunny day at ISO 100, for example! If it’s dark outside and I am taking pictures inside my home where there are no windows whatsoever, guess what? You guessed it – I’m using low aperture settings so that I don’t have to use my flash lighting up everyone else who might also be hiding behind me trying not to get caught in the picture!

mm Numbers Mean Focal Length

lens numbers

Numbers in a lens usually refer to the focal length, which is how much of a scene at a distance in front of you is shown in focus. A higher mm number means a greater focal range. The letters usually refer to the aperture set by the lens’s diaphragm blades. When reading from left to right, lower-case letters indicate wider apertures, while upper-case letters indicate narrower apertures. If there are no letters, the lens has a fixed aperture.

The following numbers and letter combinations appear on lenses:

-Focal Length (usually written as mm)

-Aperture Set by Diaphragm Blades (f/no.)

-Fixed Aperture Size (no designation)

While reading from left to right, lowercase letters indicate wider open f stop sizes while uppercase letters indicate smaller size. If there is nothing after the dash it means that particular lens will not change its maximum aperture throughout zooming in or out. This number represents how much of an area you can view at different distances in front of you will be displayed with focus; typically this range varies between 18mm to 55mm.

-Aperture Set by Diaphragm Blades (f/no.)

This number is a set amount of light that the diaphragm blades will allow to come through. If there are no numbers after f it means its fixed and will not change as you zoom in or out; if this does appear on your lens it means you can manually change the size of your aperture by twisting a ring on the lens (image above).

-Fixed Aperture Size (no designation)

If there is nothing after the dash it means that particular lens will not change its maximum aperture throughout zooming in or out. This number represents how much of an area you can view at different distances in front of you will be displayed with focus; typically this range varies between 18mm to 55mm. If there are no numbers, then either this is a prime lens which has only one focal length, or it’s a zoom where all values stay constant through zooming.

Ø Numbers Mean Diameter

The numbers on lenses are used to indicate the diameter of the lens. For example, a 2.5 millimeter lens is smaller in diameter than a 4 millimeter lens.

The numbers on lenses are used to indicate the diameter of the lens. For example, a -0.50 diopter lens is more powerful than a +0.25 diopter lens because it causes light rays from objects at infinity focus closer to your eye and lessens eyestrain nearsighted people experience when they’re trying to see far away things clearly.

Meters and Feet Numbers Mean Focusing Distance

The meters and feet numbers on lenses are typically used for focusing distance. This is typically labeled with a lowercase “m” for meters or a lowercase “ft” for feet. This is a measure of how far the subject in your photo needs to be from the camera for it to appear sharp.

Letters on lenses are often used as an identifier when there might not be any other identifying marks. Often, one lens will have only numbers and another similar lens may just have letters or no markings at all that help with identification. In this case, you want to know what each letter means so that you can get accurate information about which lens you’re using and its capabilities.

Lens Letter Key:

A = Wide Angle Lens (shorter focal length) – e.g., 28mm F= Fast Lens (allows more light in) B = Standard Zoom Lens C = Telephoto/Longer Length Lens – e.g., 70mm D = Macro Lens (allows for close-up shots) E = Telephoto/Longer Length with Vibration Reduction F = Fast with Vibration Reduction G*= Variable Aperture Zoom H*= Super Telephoto (with or without vibration reduction) I*= Professional Grade Lenses J*= Prime Lens K*= Semi-Professional Prime Lens Z = Standard Fixed lens

A few lenses don’t use any letters, but instead only numbers like 18mm, 50mm and 85mm to indicate the focal length of that particular lens. *These are not available on all lenses. Only professional grade lenses typically have letter designations; semi-professional prime and zoom lenses will often just be identified by a number.

Macro 1:1

One of the most popular lenses for amateur photographers are macro lenses. This is because they allow you to get up close and personal with your subjects, whether that is one flower, small group of flowers or insects.

A macro lens is an optical device that allows you to take pictures of very small objects that can’t be seen with the naked eye. A macro lens has a high magnification ratio – typically 1:1 life size (larger than life size) view of objects. This means the structures in the photo will look like they are life size. Macro photography can be done without a lens by using extension tubes or close-up filters, but sometimes these methods aren’t as good as an actual macro lens.

Macro lenses are typically used for close-up photography, but they can be just as useful when photographing landscapes. It’s all about getting up close and personal with your subject!

Other Lens Features

Auxiliary lens: Auxiliary lenses may be used to refocus light entering the eye if the person’s prescription changes over time. People with presbyopia, a condition where near work becomes more difficult, often use auxiliary lenses in one eye to provide clearer vision for close tasks.

Camera Lens Buttons and Dials

Camera Lens Buttons and Dials are the hardware on a camera that controls how an image is seen through the lens. To adjust for this, Camera Lens Buttons and Dials turn the focus ring to change how far out of focus objects in an image are. Changing the Camera Lens Buttons and Dial position also changes how large objects in an image appear to be.

Lens Focusing Ring: The lens focusing ring allows you to move the inner part of a camera’s lens closer or further from an object that is being photographed. Doing this changes how much light is pushed into the film plane, which controls how out-of-focus objects in your image appear. It also changes what size things in your photo will look when they are on screen.

Camera Aperture Ring: Camera Aperture Rings allow you to change how wide open or closed a camera’s aperture blades are while taking photos. This affects the amount of light taken by a camera and therefore how bright or dark an image appears when it comes up on screen for viewing later on.

Zoom Scale: Zoom Scales allow you to change the focal length of your camera lens. When a Zoom Scale is adjusted, objects in an image appear either larger or smaller than they normally would when taking pictures at different distances from them.

Focal Length: The Focal Length tells people how wide (in millimeters) that specific lens can see through it and what things will look like if viewed on screen later on. It also controls the Depth of Field for images taken with that lens; meaning how much out-of-focus light there may be towards the back end of an object’s sharpness near its front side seen in photos captured by this particular type of device.

Lens Distance Indicator: Lens Distance Indicators tell users about their distance from a subject while taking pictures. When an object is closer to the lens than what it currently reads, there will be some space between objects and their sharpness in images taken by that specific type of camera.

Lens Distance Scale: The Lens Distance Scale tells users how far away they are from an object when trying to take photos with this particular kind of device; therefore indicating whether or not you need to get closer for more detailed shots.

Camera Focal Ring: Camera Focal Rings control which part of a camera’s lens should be used as your primary shooter (another term for focal point). It allows people using one of these devices access to multiple lenses without having to switch them out each time they want a different view or magnification.

Lens Exterior Buttons: Lens Exterior Buttons are the buttons on a camera’s exterior that control how it will function all around, including what lenses you can attach to them and other features like zoom or focus rings for specific types of images.

Camera F-Stops Ring: Camera F-Stop Rings allow users to change their lens aperture size by increasing or reducing its opening area. This alters how large an object in an image appears when taking photos with this device, as well as making bright objects darker or less visible if set to closed settings.

Camera Shutter Button: The Camera Shutter Button is one of the main components on any type of camera used today because it controls whether pictures are taken or not. Pushing down on it activates the camera’s shutter to either take a picture, record video footage, or stop taking pictures after a burst of them is captured in a row.

Lens Rings: Lens Rings are part of how you focus an image when using one of these types of devices because they change the distance between objects and their sharpness when seen through that particular lens. It also controls what size images appear when sent from your device onto another for viewing later on.

This Camera Shutter Button adjusts something called Burst Mode which allows people with this type of button to take multiple shots in quick succession without having to reset it before each individual image capture takes place; saving time by snapping photos as fast as you can press the button.

Lens Hood: Lens Hoods prevent light from entering a camera’s lens at awkward angles and thus creating images that are distorted or hard to see as a result of it (such as those taken indoors without enough natural lighting). It also helps protect lenses by keeping them safe from physical damage when not in use for extended periods of time. When removed, you will be able to attach other kinds of lenses like Mic Lenses that allow audio recordings to take place with your device rather than just pictures or videos alone.

Focal Ring Lock: Focal Ring Locks keep specific parts on cameras locked into one position so they do not move during regular usage; which is important because doing so might create blurry or distorted images.

Lens Aperture Ring: Lens Aperture Rings allow people using one of these devices to change the size at which light enters it, creating larger lenses for clear pictures and smaller ones when taking close-up photos so objects look closer than they really are.

Camera Image Sensor Chip: The Camera Image Sensor Chip is a small electronic part that directly affects how much detail is seen in photographs taken with this type of camera because it captures what you see through its lens before sending those images as data onto another device like a smartphone, laptop, etc. It also helps determine where exactly an image appears on screen once downloaded from your device by zooming into specific parts of it if needed.


In this article, we’ve covered the basics of what you need to know about camera lenses and their exterior buttons. From how they work together to produce quality images with minimal distortion or blurriness, to how different settings can be changed at any time without having to switch out your lens; it’s clear that these devices are as important as ever for those who want control over their photography.