Congratulations on the big photographic jump to an interchangeable lens camera! You're probably already thinking about which lenses to put in your bag – that's why you're here, right? As cool as your new DSLR or mirrorless camera is now, it will not reach its true potential unless you take a deep look into the world of lenses. It is a somewhat sad fact that most interchangeable lens camera buyers never remove the kit lens supplied with the camera, which thwarts the purpose of a interchangeable lens camera . That's why we've put together this guide so you'll know what to look for in lenses to get the most out of your new camera (check out the purchase instructions for the whole camera if you buy one more). Investing in a new lens offers better image quality than upgrading the camera body, not to mention new creative possibilities.
Your First Step
If you have not pressed the shutter button yet, check the lens options for the makes and models you are researching. Sure, it's unlikely that anyone has to buy a dozen lenses for their camera, but the bigger the available collection, the more variety you have to choose, from wide-angle to telephoto and everything in between. Most importantly, make sure that the specific type of lenses you need for your personal photographic style are available for your system of choice. For example, if you mainly photograph landscapes, you will want a different kind of lens than if you intend to shoot mainly portraits (we will start in the details in a minute).
When you buy an interchangeable lens camera, you enter into a relationship with the specific hardware fixture set by the brand. So this is not an easy decision. For example, Nikon and Canon DSLRs use incompatible mounts, while the Canon EOS-M mirror laser series uses an even different mount (as does Nikon's still mysterious mirrorless line). With the exception of Panasonic and Olympus, who share the Micro Four Thirds mount, virtually every manufacturer sticks to its own proprietary lens mount. In some cases, you can have some sort of lens on a different type of body with a mount adapter, which is relatively common for placing DSLR lenses on smaller mirrorless bodies, but this almost always sacrifices some functionality or performance.
Additionally, while Nikon and Canon have been using their respective F and EF mounts for decades, that does not mean that every lens they manufacture is compatible with every body. Some older lenses may not be able to use autofocus on newer cameras, for example. To check Google a lens compatibility chart for your camera make and model, before you add this button to your cart. Also note that some special lenses may not offer autofocus, though you probably will not find it unless you look into the world of creative effect lenses or high-end options from premium lens manufacturers like Zeiss.  Beyond the Basics
DSLRs and mirrorless cameras – especially entry-level models – are often sold in kits, which means that they are usually supplied with a simple zoom lens that is around 18-55mm or 14-42mm and the format of your camera. A common misconception about large models with interchangeable lenses is that they inherently offer better zoom capabilities than a compact camera. In fact, the opposite is often the case. An 18-55mm lens is only a 3x zoom. That's nothing compared to a compact camera like the $ 400 Canon PowerShot SX730 HS with 40x zoom or the new Nikon P1000 with 125x zoom.
Typically, the maximum zoom performance of an interchangeable lens is about 10x, but comparing a DSLR or a mirrorless camera to a point-and-shoot is not really fair. Interchangeable lens cameras use much larger sensors, which produce very high quality images compared to compact models, but these large sensors require equivalently larger lenses. Because of this, small cameras can produce tons of zoom, while larger cameras require multiple lenses to cover the same area.
Zoom is also often confused with how close a lens can render a subject. The zoom number shows as 3x only the range from the furthest angle to the farthest angle of this lens. Zoom is a good indicator of flexibility, but not how close you can get to this lens. For this you need the focal length or the number with a "mm" afterwards, eg 50mm. In point-and-shot cameras, it is common for manufacturers to show the zoom rating of a lens (10x, 40x, etc.) while DSLR and mirrorless lenses indicate their focal length range (18-55mm, 24-120mm, etc.). If a lens has a single focal length, e.g. 50mm, it is a main lens and does not zoom at all.
Focal length and lens categories
The focal length indicates whether or not the lens captures a wide or narrow viewing angle. The focal length of the lens determines the category in which the lens falls. For a full-frame camera:
- fisheye lenses are typically wider than 14 mm (although something as far not necessarily a fisheye is)
- Wide-angle lenses typically cover between 14-35 mm
- standard or normal. Lenses sit around 50mm, give or take
- lenses with telephoto lenses between 70-200mm
- super telephoto lenses bring the subject up close, with a focal length of 300mm or more
- Macro lenses have multiple focal lengths, but allow you to use the subject very close
- Tilt-shift lenses are a type of special lens that is commonly used in architectural photography to correct for distortion
A smaller focal length will capture more of the scene as a larger focal point arises Length becomes the subject bring closer. Wide-angle lenses are then often used for landscaping or working in tight quarters, while telephotos are popular for wildlife, sports and even things like wedding ceremonies. Portrait lenses generally fall in the short telephoto range from 50 mm to 105 mm, although they can be longer. While capturing portraits with a wide-angle lens is possible, such lenses tend to create distortions. That's why your nose looks bigger in selfies; Smartphones have wide-angle lenses.
The focal length also determines how easy it is to blur the background of the image. A telephoto lens makes the background appear blurred than a wide-angle lens, even at the same aperture (which we'll talk about shortly). This is another reason why phones are popular for portraiture; They help separate the subject from the background.
While a macro lens is usually a telephoto lens, it depends on the magnification or aspect ratio of the lens, which is independent of the focal length. A typical macro lens has a 1: 1 reproduction ratio, which means that when you take a coin, for example, the image of the coin being projected onto the sensor by the lens is exactly the same size as the coin itself. So you can imagine how much detail will be visible if you look at that image on your computer screen or make a big printout.
Tilt-shift lenses, on the other hand, are designed to keep lines straight, which is why they are also used in architectural photography. They are expensive niche lenses that you probably will not encounter so early on your photographic journey.
The Numbers Game
Do not put down your phone yet; We will need the calculator. Although the focal length of a lens can be 14-42mm, 18-55mm, 24-70mm, etc., these numbers in different formats can not be directly compared. The actual angle of view you capture is affected by the size of the image sensor. The most common sizes (or formats) are Full Screen, APS-C and Micro Four Thirds. (There are also medium format cameras, but these are pretty much exclusive to professional photographers, so we'll skip them for the time being.)
To understand how a lens looks like on a format compared to another lens, we need another format convert these focal lengths into some kind of standard. The method agreed in the industry for this is the use of the focal length equivalent focal length, which is calculated using a format crop factor .
Most APS-C sensors have a crop factor of 1.5x, so if you multiply the focal length of a lens by 1.5, you get the full-frame equivalent focal length of that lens. (Canon is a weird guy here with a crop factor of 1.6 on its APS-C cameras.) For example, a Nikon D5600's 18-55mm kit lens has a full-frame equivalent focal length of 27-82.5mm. The Micro Four Thirds format is slightly smaller than APS-C and has a 2x crop factor, so a 14-42mm MFT lens has an equivalent focal length of 28-84mm. Do you notice something about these numbers? Right: A 18-55mm APS-C lens offers approximately the same field of view as a 14-42mm MFT lens. For manufacturers and formats, basic kit lenses cover approximately the same zoom ranges and fields of view.
Why is that important? In the days of 35mm film, most cameras used the same recording medium, so when looking at the focal length of a lens, the user immediately knew what angle he would take. A 24mm lens was always a wide angle, a 50mm lens was always a "normal" lens, and a 24-70mm zoom would always cover everything from wide angle to short telephoto.
Nowadays, the only lens the specified lens focal length is One-for-One cameras are full-frame sensors, such as the Nikon D850, Canon EOS 5DS or the mirrorless Sony Alpha A7 series. For these cameras, the sensor is the same size as a 35mm film. For this reason, "frame equivalent" is often written as "35mm equivalent". We stubbornly prefer the first one to avoid confusion: The APS-C 35mm lens statement has a 35mm equivalent field of view of 52.5mm
When buying lenses, always consider how the size of the sensor affects the field of view of the camera resulting images. Using a "fifty-fifty" 50mm f / 1.8 lens with a Canon Rebel T6i will not give the "normal" viewing angle like a full-frame camera. Instead, it is due to the 1.6-fold crop factor to a moderate telephoto at about 80 mm. Similarly, with a Micro Four Thirds camera, a 25mm lens is not a wide-angle lens, but is equivalent to a 50mm lens due to the 2x crop factor.
Once you've decided on your format, you really do not need to worry about equivalence anymore. Put a lens on your camera and what you see is what you get. When comparing formats, understanding the crop factor is not just about knowing what you're talking about. You can save money and make sure you choose the right camera system for your needs. Do not look at a $ 25mm f / 1.8 Olympus lens and think, "Wow, that's a lot less expensive than the $ 750 Nikon 24mm f / 1.8." These are completely different lenses. Instead, compare the Olympus 25mm f / 1.8 with the 50mm f / 1.8 from Nikon, and you'll find that the Nikon is actually much cheaper – just $ 220.