Learning about photography equipment can be extremely confusing, and this is especially true when it comes to camera lenses. I remember having to search through the internet to figure out what all the numbers and letters in lens names meant!
I the video above, we tackle all of the different things you need to know to fully understand how lenses work. My hope is that this video helps you understand how lenses work so that you can make better purchasing decisions for when you're choosing your first lens, or adding another lens to your growing camera kit.
If you don't have time to watch the video right now, you can continue reading to learn more about camera lenses.
The first part of the lens that I want to focus on is the lens mount, the part of the lens that connects to the camera. When you're shopping for lenses, you'll want to make sure that you're getting a lens that can fit your camera.
If you buy a camera and a lens made by the same company, they should work together... most of the time. See, some companies, especially companies with a long history of camera and lens manufacturing, might have several different types of lenses mounts.
Canon, for example, has 2 different lens mounts of their modern DSLR cameras (and another one for their mirrorless cameras). The EF mount is their full frame lens mount and the EF-s mount is their lens mount for crop sensor cameras.
Because the EF mount is larger, its lenses will work on the smaller EF-s mount, but it will not work the other way around because of the size difference. This is how it works with Canon, and other brands might have varying lens mounts as well. Make sure you double check that you're getting a lens that fits the lens mount of your camera.
The first number that you'll see on a lens is the focal length. The definition of focal length is the distance from the point of the lens in which all light converges, to the image sensor. This is why its written down as a millimeter (mm) value. But you don't need to remember this.
What you do need to remember is the relationship between focal length and angle of view, or how much of a view you can see. The smaller the focal length is, the wider the field of view is. The larger the focal length is, the more compressed the field of view is.
Lenses that are 24mm and wider are called wide-angle lenses. Lenses in the 40mm - 60mm range are called normal lenses and anything longer than that are called telephoto lenses.
The image bellow shows the same scene shot at different focal length, showing the relationship between the focal length and the field of view of the image.
When it comes to focal length, there are two different types of lenses: Prime lenses and zoom lenses. Prime lenses are lenses that only have one focal length. Prime lenses are not as versatile with focal length, but have the advantage of being smaller, sometimes sharper and typically have smaller maximum f-stop values (larger apertures).
Zoom lenses are lenses that have a range of focal length. Zoom lenses are more versatile but are usually bigger, heavier, and typically have a larger maximum f-stop values (smaller aperture).
The second number that you'll see on the lens is going to be written down as a ratio (something like "1 : 2.8"). This number is your maximum f-spot value, or maximum aperture. It's written down like that because your f-stop is technically a ratio, but again, this isn't something we need to remember. The only part of the ratio what we need to take note of is the number on the right side (2.8 in the previous example given).
The reason you'll want to know what the maximum aperture of a lens is, is because the maximum aperture will let the most light in and give you the greatest flexibility with depth of field. Not all lenses are built equally, and so not all lenses will have very large maximum apertures.
Variable Aperture Lenses
You might notice that a lot of kit lenses or entry level zoom lenses will have a range of maximum apertures (3.5-5.6, for example). This means that the lens will have a different maximum aperture depending on which part of the zoom range it's on.
This is typically only found on cheaper lenses because it requires less glass and simpler lens formulas.
Constant Aperture Lenses
When you move into professional lens territory, most zoom lenses will have constant apertures. This means that regardless of which part of the zoom range the lens it on, the maximum aperture will be the same.
This is good because you won't have a change of exposure when zooming in and out with the lens.
Focal length and maximum aperture are the 2 main things that all lenses have, but you're also going to run into lenses with other features as well.
Image stabilization (IS) is a feature that some lenses will have, but different lens manufacturers will have different names for this feature. IS allows you to be able to shoot with lower shutter speeds while avoiding a degree of image blur from camera shakes and vibrations. Depending on the technology inside the lens, image stabilization can allow you to slow down your shutter speed up to 4+ stops bellow what you would normally be able to shoot at without image stabilization.
When you get into professional lens territory, most lenses will be weather proof. This is a feature to look for if you plan to shoot in less than ideal weather conditions from time to time. Just remember, you'll also need to have a camera body with weather sealing to have a fully weather proof package.
Front Filter Thread
This is actually something that all lenses have, but I felt like I needed to mention it, at least briefly. The front filter thread allows you to attach anything from UV filter, polarizing filter, ND filters and more. Different lenses will have different front filter thread sizes, so make sure you to double check your lens before purchasing filters for it. It's also beneficial to have lenses with the same front filter thread so that you're able to switch lens filters between them.
I really hope this post cleared a lot of things up for you, but if you have anymore questions, don't hesitate to leave a comment or send me an email! Also, if you have any friends or family that might find this post helpful, make sure to send it their way!