I have been photographing various subjects for many years, bought and sold equipment and read more product reviews than I can remember. One word which keeps popping up in articles and my discussions with friends is “fast”.
My camera body is “fast”, my memory cards are “fast”; my shutter speeds are “fast” and my lenses are “fast”. Really? Can everything be fast? And just what the heck does fast even mean? Is fast THAT important? Let’s examine what everyone is talking about when talking about fast, and let’s do it a bit slowly....
From the time that film cameras had motors to transport film from frame to frame to today when digital cameras have the ability to take successive images by holding down the shutter button, there has been a concept of “burst rate”. The number of frames per second that a camera is capable of capturing. Limiting factors are generally the operation of a mechanical shutter, mirrors flipping up and down and the number of images the camera can hold in a buffer while transferring to a memory card. High end DSLRs have large buffers and mirror-less cameras do not have to deal with the mechanical limitations of flipping mirrors. Cameras with higher burst rates are said to be “fast” and are desired by sports photographers and for taking specialized photos such as birds in flight.
All memory cards have write and read rates. These ratings tell photographers how quickly images will be transferred to the memory from the in-camera buffer and how quickly they’ll be transferred to a computer for storage or editing. The more you spend the faster your cards can be. If you’re shooting landscapes, you may not need super duper memory speeds, but for fast moving children and pets you might. Also, if you are shooting in RAW format, you may want or need faster transfer rates since those files are much larger than JPG’s.
Most cameras have shutter speeds ranging form 30 seconds to 1/4000 second. Higher end DSLR’s can go as high as 1/8000 second and there are mirror-less bodies on the market with electronic shutter speeds as high as 1/30,000 second. So why is this important? Well, high shutter speeds are used to “stop action” or “freeze action”. It’s not the only way, but a high shutter speed may be the easiest way. If you are a portrait photographer, high shutter speeds may not be important, but if you’re capturing images of race cars at the track or ski jumpers in the air, you need it.
Lenses are probably the most confusing use of the word “fast”. Lenses have apertures that open to allow light into the camera body. Larger apertures such as f/1.8 let in much more light than a small aperture of say f/22. Since all light travels at the “speed of light”, what do photographer mean when they describe a lens as “fast”. For this explanation, we have to refer to two elements of the “exposure triangle” - aperture and shutter speed. Since a larger aperture allows more light into the camera, a higher shutter speed can be used in a given situation. An example of this would be photographing inside an old church. Typically dark interiors require you to open your aperture as much as possible. If you were using a kit lens with a maximum aperture of say f/3.5 you might need to use a shutter speed of 1/10 second, too low to get a good shot hand holding the camera. However, it you had a prime lens in your bag with a maximum aperture of f/1.8 you might be able to use a shutter speed of 1/125 second. The lens with a larger aperture lets you use a higher shutter speed and is described a “faster”.
I’d be pleased to answer any questions you may have on this and other photographic concepts. Leave a comment or send me an email. Thanks.