I again got interested in photography around 2004 when I had a chance to visit Japan for couple of months and had a fujifilm digital point and shoot at my disposal. It didn't have any manual controls but some of the pictures came out really good and I slowly started to get the hang of it. What amazed me was that digital was almost matching film quality and took a lot of the negative aspects of film cameras away and bought in challenges for the photographer.
What is a digital camera?
Cameras can be very confusing especially to a regular person who only picks one up for a family get together or an event. During the film days a camera was a lot simpler with mechanical controls and lot less complexity than their digital counterparts. Photographic film was a wonder in itself, it had a property of reacting to light and the camera used that to create negatives of an image by carefully exposing the film to light, simple. Digital is altogether a different animal, a sensor is used to mimic what a film does and create an image which the camera’s processor then copies to a memory card which you can download to your computer. Soon lots of stuff related to Photography like processing labs, films became obsolete. As I was getting to the stage where I could afford photography again digital cameras had taken hold and I had to relearn everything I knew about cameras (but not photography). It was fun and confusing and I am going to try to tell some of the stuff I have learned in the coming paragraphs.
First of all the digital revolution copied a lot from film photography, they just designed the sensor to replicate a film and used electronic controls instead of mechanical or manual controls. The new digital camera has an image sensor as its heart, this sensor copies light that’s falls on it and passes that information (a RAW file) to the Camera’s brain or an image processor which will either provide you the RAW file (in higher end cameras) or convert it into a compressed JPEG format (in lower end cameras). This image can be transferred to a computer and modified using suitable image processing software like Adobe Photoshop (the dark room of digital era). Now since the concept of camera a hasn't been tinkered with the lenses haven’t changed much other than losing some manual controls and most old ones will work fine with modern cameras albeit losing some functionality (like manual aperture control). So let’s try to explain some of the technology and aspects you need to know about the modern digital camera.
The biggest trick in the business. When I started getting interested in digital cameras and tried to get some info about them most camera salesmen used to tell me about how a camera with higher resolution will give you a better picture. Unfortunately it’s a myth that’s even now going very strong as most people like to believe that the performance of a camera can be gauged by this single number and conveniently forget that it’s a tool and like most tools a they have their specific uses. So can a camera’s ability be gauged by the sensor resolution alone? Well the answer is a big fat NO. As any tool there are multiple factors which determine the cameras ability and what a sensor does is only part of it.
Basically a sensor is an electronic contraption which mimics the physical property of photographic film and in recent years it’s managed to almost exceed the performance of film. The pixel count of a sensor is the number of pixels contained in the sensor so 6 mega-pixels means 6 million little pixels in the sensor. The sensors job is to accurately transfer the light which fell on it to the cameras image processor as bits and bytes. Every pixel unfortunately will also have some noise (a random fluctuation in an electrical signal) so the more the picture the more the noise. So the result is that pictures taken with a camera with lower mega pixel count will most often give you a picture with less noise (assuming the sensor size is the same).
Another factor is the actual “physical size” of the sensor. Since a large sensor is extremely difficult to manufacture they come in different physical sizes now from micro four-thirds to medium format. Most of the film cameras used a 135 size film whose digital equivalent is a full frame sensor (36.00 x 23.90), and most consumer DSLR’s now a days use a APS-C sensor (23.60 x 15.60) which is the size of APS film introduced by Kodak in 1996, these sensors are smaller than full frame sensors (a full frame sensor has roughly 2.33 times the area of a APS-C sensor). And the new digital only micro four-thirds sensors (18.00 x 13.5) are even smaller with full frame sensor having 3.54 the area. So essentially a 10 Mega-Pixel camera across these sensor sizes will be vastly different as the size of the individual pixels will vary. The full frame will have huge pixels and the micro four thirds will have tiny pixels, now this gets interesting when we see the advantages of a huge pixel. The light gathering ability of a pixel will greatly increase with its size and the disadvantage of lower resolution will not be able to be perceived by the human eye unless the picture is blown out to a few feet in size. Also a larger sensor will have better dynamic range and better ability to render out of focus parts of your picture more pleasingly.
Last thing we will have to discuss about the sensors are their crop factor. When you read about the focal length of a lens it’s calculated for a 135mm film or sensor. That means on a full frame camera a 50 mm lens is 50mm, easy. As you use smaller sensors they are will give you a narrower field of view as only the small sensor is only able to take the center part of the image projected by the lens. So an APS-C sensor will have a 1.5 crop factor and a micro four-thirds sensor will have 2.0 crop factor. So in essence a 50mm lens will become a 75mm lens on an APS-C sensor and a 100mm lens on a micro four-thirds sensor. This is an advantage for a telephoto shooter (as it will magically convert your 200 mm lens into a 300mm lens on your APS-C camera) but is a disadvantage for the landscape or wide-angle shooter as your 18mm wide angle is not as wide at 27mm.
More to follow soon!!