Aperture Shutter Speed - Fast or Slow Lenses

A fast lens will typically have a maximum aperture shutter speed of f/2.8 or better (some lenses can have an aperture of staggering f/1.2!), allowing for faster shutter speeds to be used compared to a 'slow lens'. This happens because the wider aperture allows more light to get to the sensor.

Slow Lens

A slow lens on the other hand may only have a maximum aperture shutter speed of f/5.6, needing slower shutter speeds (or a lot more light) to achieve a correct exposure. Remember that this aperture range can be used, normally going down as far as f/22.

An example of a slow lens is an 18-55mm zoom, which has a variable of maximum aperture shutter speed of f/3.5 at 18mm, dropping to f/5.6 at 55mm. This aspect of their construction does make them very affordable, as well as being lighter and more compact, so it's not necessarily a bad thing.

Fast Lens

A fast lens with a similar zoom range would be larger and heavier and would have a maximum aperture shutter speed of f/2.8 straight through the zoom range. You'd have greater control over the depth-of-field, allowing for the creative benefits of shallow zones of sharp focus. If you can justify the extra cost (which can be a lot), fast lenses are fantastic - large apertures, top-notch optics and the flexibility to shoot at faster shutter speeds.

Aperture Guide

f/16

f/11

f/8

f/5.6

f/4

f/2.8

f/2

f/1.4

Shutter Speed

This refers to how fast the ‘shutter’ or capture attribute fires and are measured from less then 1/30thth of a second to 1/500th or 1/ 4000th of a second.

· Faster speeds like 1/500thth are excellent for ‘capturing’ (just as a strobe light can) movement. The faster shutter speeds also allow for lower exposure (controlled by F/stop settings) such as f/2.8.

· Moderate speeds like 1/60th and 1/ 250th allow reasonable f/stops and moderate speeds and are where most work is normally done. Movement from handheld camera is more noticeable at this and lower speeds though, so when lighting conditions mandate slower shutter speeds or using low f/stops with moderate speeds it is recommended that you utilize a tripod to stabilize the image.

· Slow Speeds or less then 1/30th of a second demand a stable camera and all but mandate use of a tripod, but can be useful in allowing use of low f/stops in moderate lighting conditions. Some interesting effects such as blurred motion on a clearly defined background can be achieved with a slow shutter speed and high f/stop – you can also take images of moonlit nights or fireworks with extended (long) speed shots that otherwise are not possible.

F/Stop

Literally the amount of focal length of a lens as compared to the width of its aperture opening, the f/stop refers to the amount of light allowed in during the shutter opening. Each f/stop setting doubles the amount of light reaching the exposure media (ccd or film) and when used in conjunction with shutter speeds is the principle controlling feature of how your photographs will turn out. Lenses are often rated according to ‘speed’ or how low an f/stop they can handle – f/2.8 is excellent, but most lenses are good only from a f/4 and up range.

Many digital cameras control these and other settings in unique fashions, so reading your manual to see what each ‘mode’ setting actually controls is necessary.

Other options available in many cameras fall more into the realm of gadgets then features - for instance many of the newer digital cameras have an ”anti-shake” feature to help stabilize an image … but this can cause reduced pixel count and quality. If you are taking an image of a subject that is unsteady or if you are on a moving platform turning a feature like this on is a good idea – otherwise due to the loss of quality that goes into stabilizing the image you probably want to ensure it is off.

Another example of a feature that you need to know how to disable is the automatic flash – even at the best of times a flash will often create some rather harsh lighting on your subject, and reduce the quality of some shots, at times reflections or when backgrounds demand it they need to be off to get a usable shot at all. In other cases, such as when there is backlighting that would cause your subject to come out unusable even though there is plenty of light you may wish to force this feature to the on position. Knowing how to turn on and off these types of features that your camera offers is vital to quality work, even with the most simple of systems.