Focal Length

The use of lens is to focus an image to the sensor. Image is the subject you are shooting. Focus means to zoom in or out, sharpen or blur an image. Lens comes in different range for shooting different scenes. For this reason, the lens of a SLR/DSLR camera can be detached and changed.

Lens is mainly categorised by focal length, measured in mm. A lens may have a fixed single focal length (e.g. 50mm, 85mm). Or a range of focal length (e.g. 17-55mm, 18-200mm).

When I was making purchase for my camera with another friend, this guy at the shop showed us a few different lenses and told us many things which we don't understand. One of the thing he mentioned was crop factor which puzzled me totally. Anyway we just went WAH and WOW at the photos taken. I asked about what those mm numbers of the lenses means. He told me they don't mean much and asked me not to worry about it. How can?! I want to know what they mean and how it relate to the types of photos taken!

I came home and started reading on focal length. I realised it was something I've learnt in school. OMG! I've totally forgotten about it! So, it's back to school time.

As you can see from above, the distance between the lens and sensor is the focal length. This is what the mm numbers are all about. Next, we have to understand how different focal lengths affect the angle of view.

Take a look at the comparison diagram above. Given same distance between the sensor and the subject (tree), as the focal length changes, the angle of view also change. Short focal length gives you a wide angle of view (where you can see more than just the tree). Long focal length gives you a narrow angle of view (where you can only see the tree). In layman terms, zooming OUT means to shorten the focal length to focus a wide scene. While zooming IN means to lengthen the focal length to focus on a particular object in a distance.

Understanding A Camera

It's not about being a geek but I think it is pretty important to understand the fundamentals in a camera in order to take a nice picture. This is especially true if you are using a SLR/DSLR camera, where settings can be adjusted to affect your picture. Unless you want to be shooting with auto mode forever, leaving all settings to the camera itself. Then why the fuck buy a SLR/DSLR?!

The diagram below is brilliant! I stole it (Oops!) off here because I am lazy to draw one myself. They offer on site classes. Sounds interesting to me but I wonder how much it would cost. Anyway...

Main parts in a camera.

Leave aside the camera body. What you see in the diagram above are the fundamentals in a camera needed to take a picture. We should know that the lens of a SLR/DSLR comes seperate from the camera body and the aperture is housed with the lens.

Now, let's briefly discuss about about aperture, shutter and sensor.

Aperture
It's basically just a hole for light to travel through. In some cameras (like the SLR/DLSR), size of the hole can be adjusted to determine more or less light shall pass through. The size of aperture is denoted by "f" numbers (e.g. f1.4, f2.8, f16, f32).

Shutter
The shutter acts like a window. Closed all the time to shut off light from entering the camera. As you press the shutter release button to take a picture, you open the "window". Light travel through the aperture and pass the opened shutter to the sensor for an image to be recorded, then the shutter closes again. While the shutter stays opened, it determines how long the light (coming through the aperture) shall shine on the sensor. In other words, the shutter also determine the amount of light going to the sensor. The duration of the shutter "from open to close" becomes the measurement (i.e. shutter speed). The shutter speed is represented in seconds or fraction of a second (e.g. 30s, 2s, 1s, 1/20s, 1/1000s).

Sensor
This is where image gets recorded when you shoot a picture. In older cameras, films are the sensor we are talking about here. In digital cameras, a CCD or CMOS image sensor is used. When we say sensor here, we mean light sensitive. Too much light you get a picture over exposed (too bright), while too little light you get a picture under exposed (too dark). Changing the sensor setting, we mean to change the ISO speed (e.g. ISO 100, ISO 200, ISO 400). Setting to a higher ISO number simply increase the sensitivity of the sensor towards light (i.e. less light needed for the sensor to capture enough information). Just think of it somewhat like absorbency. The higher the ISO number, the more light absorbent is the sensor.

At this stage, I try not to get myself confused with CCD and CMOS. Just think of it as film. Hopefully when I advance later, I will then blog my notes. For the geeks... Aww... Please search about it yourself, or read here. =Þ

By now we understand that both the aperture size and shutter speed determine the amount of light that will go to the sensor. And the ISO can be adjusted according to the amount of light coming in. In other words, these three are related.

What is SLR or DSLR?

Honestly speaking, I didn't really know what SLR means when I was buying mine (a few weeks ago)! All I know the pros are using it, beautiful pictures come out from it and most important of all - I WANT IT! =D

So... What does SLR/DSLR means?

This is going to be short and simple. A SLR camera simply means Single Lens Reflex camera. DSLR is the same but digital. For this, you don't actually need to know the technical details in order to use the camera, but I will explain what I learnt. =)

Diagram makes things easy!!

A Point & Shoot camera

A typical Point & Shoot camera have a seperate window for the viewfinder. This means when you are aiming for a shot through the viewfinder, you are seeing the viewfinder image (green). While the actual photo taken is what the lens is aiming, the lens image (blue). There is a slight shifted error between what you see and the actual image taken. This error exists when you are aiming too close to your subject and it is technically known as parallax error. But digital camera nowadays comes with LCD display that allows live view. You don't get that error as the images displayed on the LCD are coming directly Through The Lens (TTL).

A SLR camera

In a SLR camera, image (light) coming in from the lens is reflected with a flip-up mirror (green) then a prism device (blue). That's what you see in the viewfinder and it's the image coming from the lens, also almost exactly the same as the picture produced. As you release the shutter to take a picture, the mirror flips up and the image goes directly to back of the camera on the sensor (e.g. film). That's the reason why you experience blackout through the viewfinder on a SLR camera while a picture is taken. Oh and I think that's very good because it always reminds me to remove the lens cover before shooting! Haha!

This concludes here. =)

A note from ME!

My interest in photo taking dates back to school days when films are still needed in cameras. It lasted only for a short period not because I lost interest, but processing the photos (most of which are craps that I shot) was an expensive hobby for a student to have. Good news came and we started to have digital cameras where you can preview shots on a LCD screen.

For some reasons, I only get to own my first digital camera more than a year ago. I had fun snapping people and things around me while putting photos on my blog. But it didn't last me long before I lost interest to shoot again. This time round not with the hobby, it's with the camera. I just felt that the photos I took were lacking some attractiveness in it. I want to take beautiful photos like those in the magazines!!

Finally, I got myself a DSLR camera. =)

Since then, I've been reading up on beginner's guide to photography written by different people. The reason because one guide may have a brilliant explaination on "shutter", but confusing theories on "aperture". While another guide might be the opposite. This actually prompted me to start this blog. I'm not trying to write my own version of guide. Seriously, I'm just a noob (but that's for now). I intend to use this as my platform of note taking. Jotting down my understanding of things that I've learnt as I go along. I am going to write everything in layman terms mainly because my English sucks. Hehe... I might write with Singlish as well because I want to feel comfortable writing - with passion. Also for other beginners who might happen to stumble upon here, I hope they would find my notes helpful.

Christa is doubting me on how long I would maintain this interest this time. I don't know too! If at anytime I stop updating here, it may not necessary be me getting sick of shooting. I'm probably just lazy to write! =Þ

Anyway, enjoy your stay!