Understanding Lenses — Kimberly Cauble Photography

Focal length, aperture, 35mm, 50mm, 85mm...prime, fixed, zoom....what does it all mean?!?

I recently started a YouTube Channel for photography education, and one of the first requests I had from 2 different viewers was to share about different lenses and what they are for. So I recorded a video about just that! I am also writing this blog post because as a teacher, I know that some people learn best through watching, and some people learn best when they can read something at their own pace and refer back to it. So if you are trying to understand lenses, what all the numbers mean, and what they are used for, keep reading!

Lenses are represented by differences in focal length, measured in millimeters. “Wide angle” lenses are usually lenses between 10-35mm. Longer focal lengths usually start around 85mm and have the ability to bring a scene closer to you.

Understanding aperture can also help you identify an important feature of a lens. Lenses that have the ability to go “lower” than 3.5, like 2.8, 1.8, or even 1.2, are going to provide you with more bokeh (blur) in your portraits. (For more on aperture, see my blog post “Understanding the Exposure Triangle,” or my YouTube video by the same title.)

Another technical aspect to understand about lenses is whether or not they are “fixed/prime” or “zoom” lenses. A fixed/prime lens does not zoom in or out…it is fixed at a specific focal length. But that doesn’t have to be limiting—you can use your feet to zoom yourself in or out! A zoom lens allows you to stand in one spot and get closer to your subject without physically moving. This is great if you can’t get close to your subject (like a skittish deer or bird in a tree) or you don’t want to get too close to your subject (I used this a lot during Covid to stay at least 6 feet away from my subjects, or maybe you’re photographing a rabid raccoon…in that case, GET AWAY…you don’t need to risk your life for a photo!)

Here are my favorite lenses and what they are best used for!

50mm fixed/prime: This lens captures a frame that is fairly close to what the naked eye is able to see. This was my first prime lens and still one of my favorites, a very versatile lens that is great for capturing portraits, candids, and scenery.
35mm fixed/prime: This wide angle lens allows me to get wide shots without any distortion, like wedding parties and large family groupings after wedding ceremonies. It is also a great portrait lens, especially for those far-away scenes.
105mm fixed/prime: I don’t know how I shot details before I got this lens. It is phenomenal for photographing details, like wedding rings, but it can be used for portraits as well! If this is not an option, you can always buy a set of magnification filters that just screw onto the front of another lens and help you get more close-up images! (This is a set similar to what I purchased to use with my 50mm lens; you just need to make sure you get the correct size for the lens you plan to use it with.)
85mm fixed/prime: This is a great portrait lens that brings your subject closer to you and creates beautiful compression/bokeh. I know many photographers who LOVE their 85mm (but it’s not really my favorite).
24-70mm zoom: This is one of my go-to lenses for weddings and portrait sessions. It allows me to get wide shots but also zoom in a bit to be creative with my compositions.
70-200mm zoom: I love, love, love this lens for weddings and portrait sessions. It allows me to zoom in closer to my subjects so that I don’t have to get in their faces and creates beautiful bokeh! It also came in very handy during the pandemic so that I could create beautiful portraits and still stay at least 6 feet away from my clients.
10-24mm wide angle zoom: I bought this to do some real estate photography for a few of my realtor-friends. I don’t like how it distorts the edges of the photos, but it sure does help me photograph entire rooms!

Below are some images I took of my friend Maria at different focal lengths so that you can see the differences! We were standing exactly the same distance away from each other, but as you can see, the images vary greatly based on the different focal lengths of my various lenses.

There are definitely more lenses for different purposes, but as a wedding and portrait photographer, these are the ones I know most about. Landscape and animal photographers have a whole different skill set AND set of favorite lenses, some much more “zoomy” than the 70-200mm— I’ve seen some all the way up to 600mm!

One last thing…don’t forget to always purchase a filter for every lens…not necessarily to change your image, but to protect the glass! My favorites are Tiffen lens filters, which you can order right from Amazon. You can also buy polarizing filters if you take lots of photos during the day and want to tone down the light a bit, just like sunglasses do.