Balko Photo

What is a single-lens reflex (SLR)?

The single lens reflex (SLR) or digital single lens reflex (dSLR) is considered the serious / professional photographer’s equipment. It is image quality and size (for enlargements) that is paramount to a photog and is the only reason he/she lugs this equipment around! Bulky, heavy, fragile, needing padded cases, it is a pain to transport. Whether on location or an airport, it will leave you wishing for a pack mule! However, if you need that type of image quality, then this is what you need to do.

Technically speaking, the Single Lens Reflex employs a mirror located behind the camera lens which reflects light toward the viewfinder while you are looking through it. Upon shutter release, it swings out of the way, allowing the light to travel from the lens travel straight to the sensor and thereby capture the image.

Before digital, a 60s or 70s photojournalist was equipped with an SLR film camera. That film sat behind the mirror. When the mirror came up the light passed through to the shutter, which opened to expose one frame of the film. With digitals, the film has been replaced with a sensor. That is the medium to capture images and the better the sensor, the better the images.

You might be familiar with the Point and Shoot models that offer a Live View - that LCD screen on the back that shows the image and allows you to compose it before pressing the shutter release. DSLRs did not offer this option until recently and there  are lively discussions as to the value of it. My Canon 40D has this feature, but I admit that I have never used it! I am far more comfortable using the viewfinder, plus the fact that holding the camera away from your body results in more movement. Add to this the heavier lenses, and it really is not feasible to hold a 4+ pound camera/lens combo far outward. This means that more professional photographers will not use it much beyond basic landscape or macro use. Technically, that Live View locks up the mirror, and a prism sends the image to the LCD rather than to the capture sensor.

Megapixels and Sensors

When looking for a digital camera, most people start off with the number of megapixels, thinking that the more mp the camera offers, the better it is. This is a fallacy.

First, the average person does not need the large size or large price tag of a higher megapixel camera. Even your 1.3 mp camera phones are fine for Web use. A 4 or 5 MP model is great for Web and smaller prints. 6 to 8 MP will allow you to print a bit larger - up to xxxxx. Upwards of 9 and 10 megapixels is getting into the professional category.

Photons, we need photons and the more the better! If you want great dynamic range and the ability to make large poster-sized prints, then you need a camera with a large sensor. DSLR sensors are larger than the ones in Point and Shoot models. This allows more photons to hit the sensor and better performance in dim light. Get the best sensor you can afford at the time. Remember that you can (and will) change the camera body, but a good lens will last you for a lifetime! Your lenses will determine your image quality and yes, they can be very expensive. Having been through many lenses, I can tell you that one super quality lens is worth way more than 3 or 4 mediocre lenses.

Types of dSLRs

Big Sensor with Big Lenses: Expensive yes, but oh the image quality! Once you have experienced this, you will have a very hard time accepting anything less. The really big (full-frame) sensor equals reduced image noise (graininess), which can really ruin an image especially in low light or high-ISO situations. The full-frame sensor is the same size as 35mm film resulting in no crop factor. This is great on the wide end, but limits you more on the telephoto end. Some models: Canon 5D, the Nikon D3, Canon’s EOS-1D Mark II / Mark III.

Smaller Sensor with Big Lenses: Using a smaller sensor reduces the price of a camera.  Since 35mm system lenses are still used with it, not all of the image is captured. The edges fall off so you do not get what is on the outer right/left, top and bottom of the frame. It is the difference between looking through a 50mm lens and a 100mm lens. The 100mm lens captures less of the image than the 50mm, though closer. Nearly all the popular digital SLRs fall into this category.

Small Sensor with Small Lenses: Here is a more logical approach — the four-thirds system. Olympus and Kodak were the originators of the standard but Fuji, Panasonic, Sanyo, and Sigma have signed on as well according to www.four-thirds.org.

If you don’t need the latest technology (with its big price tag), and shoot mainly telephoto, consider the Olympus E System. It is a good choice and the 2x crop factor is a huge bonus for telephoto shots. In the smaller and lighter dSLR systems, the Oly E-510 is a great choice. Plus it won the 2007-2008 EISA Award as the “Best Consumer Product.”

Most photographers have a budget which constrains us, so we compromise with the less expensive smaller sensors/big lenses combination. An option for lenses are the digital-only lenses that fit the mount for a 35mm film camera but optically cover only the small sensor of a mid-range digital SLR. They do not work on all the manufacturers models (like full-frame), and have designations like Canon’s “EF-S” lenses and Nikon’s “DX” lenses.