This guide and our group photography workshops assume that your camera falls into one of two categories, either an interchangeable-lens camera (ILC) or an advanced enthusiast-level fixed-lens camera.
There are two types of digital ILCs, digital SLR and mirrorless. Let’s explore their basic features.
Digital single-lens reflex cameras
At the time of writing, digital SLRs remain the top-selling ILCs, a trend corroborated by the cameras I most commonly encounter in my group photography workshops. The primary feature of a digital SLR is that its lens forms both the optical image in the viewfinder and the image projected onto the digital sensor to make the photograph. In the film era, this feature separated SLRs from more traditional viewfinder cameras, which used separate lenses for their viewing and picture-taking systems. Employing a single-lens design solved the problem of parallax—where the apparent position and rotation of a subject are different when viewed from slightly offset perspectives. Since the separation distance of the lenses in two-lens viewfinder cameras could be as much as the distance between your two eyes, achieving precise framing, especially of close subjects, was nearly impossible.
SLRs use a hinged mirror assembly to facilitate using a single lens for both the viewing and picture-taking systems. The image in the optical viewfinder is formed when light passing through the lens is reflected up (hence reflex) towards a ground glass focusing screen by a mirror angled at 45° to the lens axis. A pentaprism or pentamirror divert the image into the viewfinder’s eyepiece. When taking a photograph, the mirror swings up and out of the light’s path letting it expose the digital sensor.
Advantages of digital SLR cameras:
- Accurate composition. The viewfinder displays the image formed by the camera’s lens and faithfully represents the focus, depth of field, and composition of the resulting photograph.
- No delay viewing. The optical nature of the system means that you see the image in real-time, without delay.
- Optical viewfinder. The optical viewfinder ensures that you see the full tonal range of the scene with your eyes.
- Fast autofocus. The “phase detection” autofocus system in digital SLRs focuses on your subject very quickly.
Disadvantages of digital SLR cameras:
- Bigger and heavier. SLRs are generally larger and heavier than equivalent cameras because the mirror requires a large volume of space within the body of the camera.
- Mechanically complex. The mirror and its movement add significant mechanical complexity to the system, increasing its price.
- Viewfinder blackout. The image in the viewfinder briefly disappears because the mirror must lift out of the way to allow the light to expose the digital sensor.
- Mirror vibration. The mirror’s quick movement can induce vibration in the system at slower shutter speeds.
- Larger, complex lenses. The volume of space occupied by the mirror and its components mean there’s a long distance between the back of the lens and the digital sensor (flange focal distance). In particular, this makes the designs of wide-angle lenses more complex.
Mirrorless interchangeable lens cameras (MILCs) are designed to improve upon some of the shortcomings of digital SLRs, and it’s accomplished by replacing the optical viewing system (mirror, focusing screen, pentaprism) with an electronic viewfinder (EVF), rear LCD, or both. During regular operation, light passing through the lens projects directly onto the digital image sensor, which generates and transmits a live video stream to the viewing system. When a picture is taken, the digital sensor briefly ceases transmission of the video stream to record a photograph at full quality.
Advantages of mirrorless cameras:
- Smaller and lighter. The camera bodies tend to be smaller and lighter than comparably equipped digital SLRs due to the absence of a mirror and its housing.
- Exposure preview. The viewing system shows an accurate representation of the image formed by the lens, and on many models, can simulate the final exposures, white balance, and picture profiles (i.e., what you see is what you get).
- Exposure aides. The viewing systems in advanced models may present additional aides such as exposure warnings, the histogram, focus assist, and more.
- Low-light viewing. The viewing system can provide a brighter view than can otherwise be achieved with an optical viewfinder (or the naked eye) in low-light conditions.
- Precise autofocus. The contrast detection autofocus systems used by many mirrorless cameras are typically more accurate in focusing the subject.
Disadvantages of mirrorless cameras:
- Poor battery performance. Because the electronic viewing system is continuously engaging the digital sensor, MILCs have much weaker battery performance than digital SLRs.
- EVF/LCD lag. Since the electronic viewfinder must process the video signal from the digital sensor and display it for the user, there is a perceptible delay compared to the optical viewfinders of SLRs. The degree of the delay varies between models, with modern higher-end cameras having shorter lag times that border on the imperceptible.
- EVF/LCD resolution. Whereas the visual acuity of your eyes limits the resolution of the optical systems in digital SLRs, small pixel dimensions limit the resolving power of EVFs and LCDs of mirrorless cameras. This makes visual assessments of shallow focus and depth of field difficult and can produce distracting moiré patterns in finely textured subjects.
- Slower autofocus. Contrast detection autofocus, while accurate, is noticeably slower than the “phase detection” autofocus systems used in all digital SLRs and some higher-end mirrorless cameras.
All fixed-lens cameras share two common traits: 1) their lenses are permanently integrated into the camera bodies and can’t be removed; 2) they are mirrorless by design. This market category encompasses a tremendous variety of styles, ranging from the very basic auto-everything point-and-shoots up to enthusiast-level compact cameras featuring a full range of manual exposure controls and more. This guide and our group photography workshops are intended for photographers using the latter type of fixed-lens cameras. A simple method for determining if your compact camera offers this level of control is to check whether there’s a mode dial on top of the camera with the following letters printed on it: M, S, A, and P (or M, Tv, Av, or P for Canon, Pentax, and Leica models).1 There are a couple of notable exceptions to this rule, such as several Fujifilm X series and Panasonic LX100/Leica D‑Lux series compact cameras.
Advantages of fixed-lens cameras
- They’re portable. Fixed-lens cameras tend to be very small and light compared to ILCs because they lack a mirror box, integrate lenses physically deeper into the camera body, and typically use small format sensors.
- Versatile lenses. Most compact cameras with zoom lenses feature a versatile range that can capture both wide and narrow angles of view.
- Grab and go. Everything you need as a photographer, whether it be a flash or a versatile lens, is built-in. Limitation, as it turns out, is freeing; being limited to the one fixed-lens means that you don’t have to deliberate about what lens to bring for each excursion, which is a common source of anxiety for many photographers.
Disadvantages of fixed-lens cameras
- Poor lens options. You only get one opportunity to choose a lens, and it’s at the time of purchase. What if the lens you want comes on a camera you don’t? What if your preferred camera doesn’t have the right lens? You’re out of luck if you desire a super wide-angle lens since no compact cameras have them. The opposite end of the zoom spectrum is easier to accommodate; there are several compact cameras with very high magnification zoom lenses, although they tend to achieve such feats with significant compromises to image quality.
- Limited selective focus. A photographer’s ability to selectively focus on one subject while simultaneously allowing the rest of the scene fall out of focus is primarily determined by the combination of their lens and camera. The quality of how much of the scene is in focus is known as depth of field. In general, the design trade-offs that allow fixed-lens cameras to be compact diminishes your ability to isolate your subject from the background with selective focus.
- Slow zooming. The zoom mechanisms in compact cameras tend to operate on a fly-by-wire principle, where pushing a button or nudging a lever engages an electronic motor that drives the zoom. These tend to work in distinct steps, and not smoothly.
- Slow focusing. Assuming you have the option of manually focusing the lens, the focus mechanisms in every compact camera are operated by the fly-by-wire principles. Additionally, most compact cameras use the contrast detection method for autofocusing their lenses, which, although accurate, is relatively slow.
- Poor ergonomics for manual control. Increased automation is a double-edged sword. Cameras designed for auto-everything operation often sacrifice your ability to access manual controls easily.