Last week I mentioned that I want one of the new Nikon D200 cameras.
Why, you may be asking, would I want such a thing if I have a perfectly good camera already?
The short answer is that this is a DSLR camera. That’s a Digital SLR camera. That means Digital Single-Lens Reflex camera. Got all that? If you want the technical definition, lookup SLR on Wikipedia.
In practice, when referring to a digital camera, the term SLR refers to a whole family of design decisions.
First and foremost, it means that the sensor is bigger than in a typical compact digital camera. My understanding is that it’s about 5 times bigger in each direction, which means it has 25 times the surface area. That’s hugely important, because when the shutter opens, it receives 25 times as much light. There’s no need for more light, so the instead the camera is set up to receive the same amount of light in 1/25th the time: It can use a faster shutter speed in low light, for less motion blur.
The D200 divides that light over 10 million pixels, which is 2.5 times as many as my current camera, resulting in a theoretical (25 / 2.5 =) 10-fold increase in light gathering per pixel. In fact, the D200’s specifications show an 8-fold increase in maximum sensor speed over my Z3 (from ISO 400 to ISO 3200 if that means anything to you).
A second advantage is that (for reasons having to do with physics I don’t quite follow) a larger sensor causes less visual noise (grainy fuzziness) in the images it captures. All other things being equal, the images from a larger sensor are much clearer. Or, again, a trade-off is possible, allowing shooting in lower light without increasing the image noise.
One downside of having a larger sensor is that other parts of the camera have to be built larger to match. The most costly part to enlarge is the lens, which is why SLR cameras use a set of smaller interchangeable lenses instead of one gigantic all-purpose lens. This reduces the cost of the optics a lot, and it allows for an even greater range and quality of lenses.
In order to make sure that the photographer sees the view that the film is going to capture regardless of which lens is mounted, a special optical system is used so that the viewfinder and the photo sensor share the same lens. A mirror is used to switch between the two. This is the Single-Lens Reflex system that gives the camera its name. It also adds to the weight, size, and price of the camera.
Once the engineers have decided that the camera is going to be big and cost a lot, it becomes easier to add other features and performance improvements. I’ll have more to say about that in another post.
Click here for more Nikon D200 information.
Update: Part 2 Is Up.
Leave a Reply