You are putting the pedal to the medal with that cybershot, great work! There are two general classes of still cameras:
A) Point and Shoot
Sony Cybershots, Canon Powershots, Nikon Coolpix, and Kodak Easy Shares all fall under this category among many others. The flash, sensor (digital film), lens, and everything else come in one package out of the box.
B) DSLR (Digital Single Lens Reflex) or SLR for film
These cameras come with...well, a camera. The lens is a separate piece which can easily be removed and replaced with a different one. This allows us to use several lenses, each designed to handle specific scenario.
Point and shoot cameras are a much less expensive route because there is much less hardware to buy. They are a "jack of all trades, master of none" handyman package. A DSLR can serve as a plumber, carpenter, underwater welder, or whatever else as long as you have the necessary pieces of the puzzle. Each piece should do its job better than a point and shoot if used properly, but they may fair worse than a point and shoot at jobs they were not designed for.
That is the most basic explanation I can muster in the DSLR vs. Point and Shoot argument.
The quality of the DSLR camera itself, which we will call the body from now on, is usually much better than that of a point and shoot camera. For one, they typically have much larger image sensors. Think of a sensor as a roll of film. Instead of a 24 frame roll it is a single frame that you can develop, record to a memory card, and re-use in a fraction of a second. Pull some old 35mm negatives out of the dresser and look at their size. If you had a 35mm image sensor, it would be the same size!
Point and shoot cameras typically do not have 35mm image sensors. This is a nifty diagram that belongs to wikipedia.org:
Your Canon PowerShot SD1100 IS has a sensor size of 1/2.5". Note 1/2.5" is the smallest green box in the diagram above. Say, I thought you had a Sony Cybershot? Well, you obviously got some decent results with your 1/2.5", so what is the difference between that and the others? Price for one. A 35mm digital image sensor (just the sensor never mind the rest of the body) could run $1k++.
I want you to look at your computer monitor. No, no, I know you are looking at it right now but I want you to get up close and personal. Put your eyes as close to the screen as you possibly can and what do you see? Squares. Lots and lots and lots of squares. Each of those squares is a pixel and each pixel represents an individual color. The text you are reading isn't letters at all but a bunch of black, white, and grey squares placed in a specific order. Digital image sensors record light coming through your camera lens with similar pixels. Your *PowerShot* SD1000 has 8,300,000 pixels on its image sensor, or 8.3 megapixels.
That's a lot of pixles, and they are all in that tiny 1/2.5" box above crammed like sardines! As if a possible drop in from PETA (People for the Ethical Treatment of Androids) wasn't bad enough, those pixels are doomed to a life of lower quality because of their compact nature. Digital noise becomes a big problem on 1/2.5" image sensors as you crank up ISO speeds. If you had 8.3 megapixles on an APS-C sensor (Canon's smallest DSLR sensor, see above), you could use higher ISO speeds with a sigh of relief.
What is ISO you ask? Well when you take a photograph there are 3 main aspects that control it. A triangle if you will. ISO is one corner, Shutter Speed another, and last but not least Aperture.
ISO speed determines how sensitive your camera sensor is to the light which hits it. The light entering the camera isn't enough to display the proper brightness of the scene, so a high ISO can amplify the signal to make it brighter. Some information is lost in transition which shows up as noise, or speckles all over the image. Combat "œnight vision" goggles work using super high ISO speeds.
Shutter Speed is a measure of time in seconds. It represents how long the photo was actually taken. 30 seconds would be a long exposure, 1/100 of a second would be an average speed, and 1/8000 of a second would be very fast.
Aperture is a measure of the lens's diameter compared to the focal length. By focal length I mean a 50mm lens or 135mm lens, ect.
Think of a slip and slide you played on as a kid in the summer. You have to get the "slip and slide" nice and wet or it will just be a "slip and cry". Instead of a garden hose with a gate valve, you have a well pump with an on and off switch and a hose with selectable nozzles.
How long you turn the pump on to let the water out is like shutter speed. A Longer pump time = more water; A Longer shutter speed = more light.
How wide of a nozzle you select is like aperture. A wider nozzle aperture = more water; a wider lens aperture = more light. I can even use the same term with that one.
Now here is the kicker, and I mean this is REALLY important. Shutter Speed, Aperture, and ISO are all broken down into measurements called "stops". A stop of any of the three is equal in *amount of light* to a stop of the other two. They look like this:
Shutter Speed (most light [longest] to least light [shortest]): 30 seconds, 15 seconds, 8 seconds, 4 seconds, 2 seconds, 1 second, 1/2 of a second, 1/4 of a second.
Each time you move a stop, the shutter speed halves itself.
Aperture is harder to see because it's a measure of diameter, but the stops look like this (most light [widest] to least light [narrowest]): f/2, f/2.8, f/4, f/5.6, f/8.
(2.8) x (square root of 2) = 4 is the pattern.
So a Shutter Speed of 1/100 of a second and an aperture of f/4 will have the same brightness level as a Shutter Speed of 1/50 and an aperture of f/5.6
Well what happens if you are taking a picture at night time and you've pushed the shutter speed and aperture to the max? What would you do if the well ran out before we got enough water on our slip and slide? Put soap on the slip and slide to make the water wetter!! Similarly, we can crank up the ISO speed to amplify the light that hits our image sensor.
ISO speed stops (from least light to most light) are 100, 200, 400, 800...
Well I'm getting sleepy so respond with any questions and I'll pick this back up later.
