Before we get too far into this, we need to have a brief discussion of what a prime lens is. There are two basic types of lenses (yes, there are more, but they are far less common) that we use on a regular basis, prime lenses and zoom lenses. Zoom lenses have a variable focal length (e.g. 24-70mm or 70-200mm) so you can zoom in and out from the subject. A prime lens has a fixed focal length (e.g. 30mm, 50mm). Prime lenses tend to have wider apertures than regular zoom lenses. The downside to prime lenses is that if you need to zoom in or out to compose your scene you “zoom with your feet”. Deciding what you want is purely a personal decision and there is really no right or wrong. While wedding photographers typically shoot with zoom lenses to make it easier to adjust for specific scenes, there are also some that prefer prime lenses due to personal preference. Likewise, while most portrait photographers tend to shoot with primes, there are also some who tend to use zooms because of personal preference as well. Clearly, personal preference is a factor that plays into your decision-making. Having said that, there are also other considerations to take into account
Choosing a Prime Lens
If you want a super fast lens or want that really shallow depth of field, a prime lens can be an excellent choice but picking one out from all the different sizes can be a little daunting. Deciding on a lens really depends on what you plan on shooting. Landscape shooters may want a wider field of view, jewelry shooters may want a longer focal length macro lens, and portrait shooters may want something closer to 50mm to avoid any distortion caused by shorter or longer focal lengths. If you are shooting people, I suggest something between 30mm and 70mm. The cheapest lens you can get is the Nikon or Canon ”Nifty-Fifty” 50mm f/1.8 which will run you about $99 or so. If you want to try out a prime lens without a large investment, these 50mm lenses offer a nice entry point.
If you are not using a full-frame camera body, then keep in mind your crop factor as it will increase the focal length. On APS-C sized sensor (Canon 30d, 40d, 50d, etc) you have to multiply the lens’ focal length by 1.6 so a 30mm lens becomes 48mm which is almost perfect in terms of distortion. The Sigma 30mm 1.4 EX DC HSM is an excellent choice for portrait and product photographers. This is probably one of my personal favorite lenses due to the size, the light weight, the lack of distortion, the super fast f/1.8 aperture and a cost around $450.
Moving up in the focal length, once we get out of the common portrait sizes we get into the longer lengths like 100mm. At this length, there is a compression added to the image that can make things look slimmer than normal so it actually can make for a good portrait lens even though many people may not think to use it as one. I like using this lens for small products such as jewelry or things that have a lot of detail.
With the Sigma 105mm f/2.8 EX DG Macro lens not only gives you a nice long focal length but because it can focus at very short distances it can also create images that are life-sized, this is great for close-ups on things with lots of detail such as wedding ring shots.
Hopefully this has given you some insight into why you may want a prime versus a zoom lens and how to go about choosing the lens that is right for you. As you can see, I am not a purest when it comes to lenses and I have been shooting weddings with a Sigma 24-70 DG for several years. Whatever your brand, whatever your need, do your research and figure out which lenses shoot your shooting style, subject matter, and budget.
Culled from CameraDojo