This series of news articles is intended to help the novice digital photographer who wants to learn more. The aim is to explain key terms and introduce new ideas to help you, as a novice, explore the world of digital photography.

What does that mean? Common terms used in the world of digital photography! Part 2

In Part 1 of this topic, we looked at SLR, DSLR, Sensors, Lenses, Difsuers, Pixels and Resolution. Time to move on to the interesting bits..


Shutter Speed
In terms of digital photography, shutter speed is slightly different to traditional photography. With traditional (film) cameras, the shutter opened when you pressed the shoot button, exposed the film behind the shutter, and then it closed again; covering the film back over in the process.

With the electric sensors in your digital camera, the "shutter" is controlled by the camera's computer. A short shutter speed means the sensor is charged for a fraction of a second which only allows for a small amount of light to hit the sensor. For longer shutter speeds, the sensor is kept charged and open for longer, which allows more light in.

These days though, the shutter noise made by most digital cameras is created by a small speaker in the camera and really only mimics that of a real shutter. It’s useful though: it lets you know when your photo has been taken!

Shutter Delay
It can be frustrating sometimes: you’ve got that perfect shot lined up, and the digital camera seems slow? Shutter delay is a term used mostly by digital photographers, and refers to the time between pressing the shutter button and when the camera actually takes the picture (your camera needs time to set its automatic focus!).

Well, to overcome the problem in most digital cameras, you can generally "pre-focus" by pressing the shutter button halfway, and once the focus has been locked the shutter can be pressed fully.

While the problem may occur in DSLRs if you use the built in automatic functions, it’s less apparent. Getting to know your camera helps a lot, and using manual settings and focus, is not as hard as you think!

Aperture
Ah, the good stuff? One of the most common terms you hear people using in photography is the word aperture! The aperture is simply the hole inside the camera lens that allows light through onto the sensor.

Aperture is measured in “f” numbers, which is just a ratio of the diameter of the hole and the focal length of the lens. DSLR cameras (and some general digital cameras) allow you to change the size of this hole: a larger hole allows more light in, a smaller hole allows less. Easy as!

So why is it important? Well, among other things, it has a major effect on the depth of field! A smaller aperture (higher “f” number) produces a lot of depth of field (see below). The reverse happens with a larger aperture (smaller “f” number). The great thing about DSLRs is that they can produce a board range of depth of field effects, so have fun playing around! Compact / general digital cameras usually can’t, but don’t let that stop you from seeing what your can do (read your manual!).

Depth of field (DOF)
We’ve all seen the comment on someone’s photo “great DOF”, and I guess it’s a compliment really?! So what does it mean? Depth of field is just the measure of how much of a scene (from the front to the back of the image) will be in focus (or how “deep” or “shallow” the view goes).

For portrait or close up photography, its common (and often looks best) to have a “shallow” depth of field (i.e. keeping only part of the image in focus). This allows the subject of you photo to be in clear focus, yet makes the background blurred a little. In landscape photography though, usually you want everything in focus, from the cow or the fence in the foreground to the tree and the hills in the distance (this is a "deep" depth of field).

Examples of shallow DOF (focus only on subject) include:



Examples of deep DOF (all image in focus) include:



Noise
Noise for digital photographers is the equivalent of film grain in traditional photography. It generally shows up on digital photos as small coloured blotches, usually in the darker or sometimes lighter areas of an image. While you probably don’t care about noise in your everyday snapshots, you probably will in your artistic work, especially if you want to make things for large view or printing.

Noise is worse in digital photos when they are taken in low light or night photography, in cameras with smaller sensors (less megapixels), or where the aperture or digital ISO level has probably been bumped up too high and the sensor is unable to deal with or adjust correctly to the extra light. Noise can sometimes be removed or lessened to some extent by computer software (like Photoshop or GIMP) though.

Now, while film grain can sometimes add atmosphere to a photo (that old feeling), digital noise is generally ugly and unwanted. Digital photographers who want the "grainy" effect in their work tend to start with a clean image (i.e. no digital noise) and then add the grain effect afterwards themselves using software.

Digital Camera ISO
ISO is another common term used in photography, which stands for International Organization for Standardization. With traditional film cameras, this referred to the speed of the film and its sensitivity to light or, more simply, the amount of light that was necessary to expose the film (it was often called slow or fast film, see also here). The higher the ISO sensitivity, the more light would be absorbed onto the film.

With the age of digital photography though, most digital cameras have an equivalent to this, which we still call ISO. Your digital camera can be set to determine how much light you allow into the sensor, which in turn increases the exposure level (brightness). Just like traditional film though, greater exposure comes with a potential loss of image quality, although with digital images the loss is seen as image noise rather than film grain.

Potentially, if you’re in a low light setting you have 3 choices to help you out. You can increase the ISO setting which allows more natural light in, even at greater distances (but also noise); you could increase the ISO only slightly and extend the shutter speed (you’ll probably still get some noise), or you could use your flash! It really depends on the subject of your image as to which option/s you chose.

An example of digital noise through the use of ISO can be seen in *thenuke’s work..



File format
In film photography, your photos are recorded onto film which is light sensitive which is then developed with specific chemicals and a negative is produced which you can print photos from.

But as we touched on previously, in digital photography your photos are stored as a digital file on your memory card. There are different types of file formats used in digital photography. Some are “lossy” (the image may be compressed or the quality reduced) and some are “lossless” (the image is full quality and unchanged). Obviously, the higher quality the image, the bigger it is and the more space it takes up on your memory card, so you may be limited by this sometimes.

Generally, most digital cameras record images in the popular lossy file format JPEG. With DSLRs and larger memory cards, you usually get a choice between the two formats and you could chose to record your image in the most common lossless file format, either TIFF or RAW. I guess it depends on what you want to do with the image afterward as to whether you chose JPEG or something else, but generally JPEG is pretty good!

Post Processing
In the days when film photography was the thing, editing of photos was work generally done in the darkroom. Not just developing the photos, but all sorts of things could be done if you knew how: correcting colours, lifting dark areas of a scene, blending two photos together, adjusting the contrast, that sort of thing.

As far as digital photography is concerned though, post processing means you’re using image editing software. The same adjustments and tweaks that you could do with film can be reproduced with software!

The most common photo editing software used these days is Photoshop (CS3 is just out, and it’s great!), however there are other free programs such as GIMP which are quite popular too!


Some links to consider:
http://www.dpreview.com/
http://digital-photography-school.com/blog/
http://digitalphotography.tipcentral.net/
http://www.lexar.com/dp/


Future Editions:
Rule of Thirds
Exposure and how it works
Lighting and Flash
Optical vs Digital Zoom
Lenses and Filters
Special Photography Secrets
Macro special…


Past Editions:
What does that mean? Common terms used in the world of digital photography! Part 1



So what are you waiting for? Go and have some fun taking photos!
Cheers,
Cath