2. SLR elements
An SLR (Single Lens Reflex) camera, regardless digital or analogue always consists of its body and the lens as illustrated below.
Attaching the lens, simple…yet important.
The simple yet important point to remember is that whenever we want to attached a lens to the body, always align the body and the lens properly before twisting the lens to locking position. As illustrated above, the red marker showed the white line on the lens and the white circle on the body to be aligned.
This kind of marks are standard for different types of lenses, here’s another example: 
Many times, we may be tempted to just twist the lens a whole 360 degree 
hoping to get to the right spot eventually. The problem is that twisting the lens before its properly align may damage the electronic contacts of the lens, as seen on this image: 
.
The lens
Lets take a look at a common kind of lens that we will come across, described in the photograph below.
The focusing ring will be used to adjust the lens based on the distance of the object that we are photographing. In the example above, the measurement comes in two metric, feet (ft) and meters (m). This control is very straightforward, if the image is not sharp, then it’s out of focus 
The next ring below the focusing ring, is the focal ring; this ring controls the magnification of your object. I’m not going into the mathematical depth of focal length, basically the larger the number, the higher the magnification is. Focal length is commonly denoted using F character/
Below the focal ring is the aperture ring. The aperture ring controls how wide the lens opens up, or in other words how much light are allowed to go pass through the lens into the camera sensor (digital) or negative (analogue). Again we won’t get into the mathematical details. A practical rule of thumb is: “less is more”; the smaller the number, the wider you open up, the more light goes through the lens. For example: f/ 3.5 allows more light passing through then f/16. Aperture is denoted with f.
You may notice that some of the rings, in particular the aperture ring do not exist in some newer lenses, this is because the corresponding settings are controllable through the camera body.
Aperture’s involvement will be discussed more on the next section: Bite 3: Speed and aperture – the root of quality shots.
December 26th, 2008 at 4:26 am
hello…i’m thinking to buy a DLSR camera,and maybe I’ll buy canon 400d,I know nothing about camera,i’m using minolta Z20 at the moment which is an all around camera,my question is,how do you set the Aperture and the ISO?for example in a fine day at 12.00,the location is outdoor,and the object is flower,what ISO& aperture should I set?please reply.
thank you.
gabriel
December 26th, 2008 at 9:37 am
Hello Gabriel,
Thanks for your comment firstly. The basic skills to use an SLR is indeed the aperture, shutter speed and ISO. It is an area that can be explored in a full article. I’ll try to be brief and practical.
Using the z20 you should be able to practice your manual exposure control quite well, I used to use the A1 myself as my first digital camera.
Regarding the ISO, generally you’ll want to use a lower ISO like 100 or 200 to minimize the amount of noise in the image. The lower the noise, the better quality your prints will be if you enlarge it. The ISO controls the sensitivity of the camera sensor, how receptible is it to light. The higher the number, the more sensitive the sensor will be.
The aperture is how large your lens aperture blade opens up when shooting, the larger it opens up the more light it allows in (to the camera sensor), the brighter your picture will be. Generally the smaller the numbers (f / 1.4 or f / 2.8) the larger aperture.
The shutter speed is the length of time in 1/X s your camera opens up allowing the light to hit the camera sensor. The longer the shutter opens, the more light your sensor “absorbs” the light, the brighter your image will be.
So there is no set settings for one fine day, it all depends on the light condition on the day. Play with the aperture and shutter to allow the amount of light that can enters the sensor for a lower ISO. As a generic rule, the smallest speed that you can use to avoid blurring by movement is 1/lens length. So if you zoom in to 60mm then the lowest speed you can use is 1/60s.
If you can’t get a good image with the current ISO that you are using, then you have to increase the ISO.
February 22nd, 2010 at 7:30 pm
Hey Arvy.. long time no see. Just want to ask u something.
My brother got my first DSLR camera Canon EOS Kiss F with the standard EF-S 18-55mm 1:3.5-5.6 IS Lens. I’m still a beginner but I wanted to ask which lense would u recommend for the next level up? I’ve been looking at EF-S 18-135mm f/3.5-5.6 IS Lens
June 30th, 2010 at 7:02 am
Hi Suzanna, it’s been a while indeed, hope you are well. I haven’t been watching the blog for a while because of other commitments. In general I suggest getting a lens with fixed aperture, this gives much more flxibilities in different lighting conditions.