Many have heard about the

Many have heard about the "dill factor", as well as DX-FX-cameras d3100 and cameras, but few people understand what it means. In fact, nothing complicated about it. There is a misconception that allegedly using the same lens on FX and DX cameras and its focal length is changing, d3100 and it must multiply or divide d3100 by Crop factor. This is all speculation of uneducated people, but first things first.
Historically 35mm film (or rather, its size 24h36mm) was and still is very popular. At the dawn of the digital era Nikon wisely decided that it would be nice to make a digital camera so that you can tie to her old lenses that were produced for decades.
The idea is good, but implementation had problems. Make full frame sensor is too expensive, but very very small - makes no sense. The result was found "golden d3100 mean" - technology that was diagonally in half (1.5) times a frame of 35mm film. 1.5 - a Crop factor ("dill" in English - scrap). By the way, Canon has found the optimal d3100 solution in the form of Crop factor 1.6. Dill named for Nikon DX.
There DX-lens, so that the area of the sensor decreased by more than 2-fold and could save money in the production of expensive optics, thus making the DX-technology accessible to amateurs. Here is a graphic picture d3100 of how much reduced area sensor:
The first rectangle - a 35mm film or FX sensor. Second - DX-sensor compared to FX. The third - a 4: 3 format, which is widely used Olympus, Panasonic, as well as many others. In the bottom row of typical sensor "cameras". For example, the bottom right, which is 1/2, 5 ", in the popular Canon A470. FX-sensor d3100 is full frame, appeared relatively recently and is identical to the size of a frame of 35mm film and works perfectly with all old lenses.
Why is there a zoo sensors? d3100 The thing is the price. Even in the "age of STD" (STD - scientific and technological revolution, as told my teacher of geography, but no one could understand what that means), production FX-sensor costs about 20 times more expensive than DX. Therefore FX-cameras are expensive. Crop factor Himself Very important role osushytel When running on air polnuyu and predstoyt Set Very Much photographer.
But what, after all, these sensors d3100 give us? In the case of Nikon we get excellent compatibility with all Nikon lenses save money, but what's the catch? Machinations that in lens with a focal length of 35mm, such as the DX-camera viewing angle is narrower than the FX-camera. This is well illustrated by a title image.
This is where the confusion of many. Angle for DX-chamber tapers so as if you are on a FX-camera d3100 looking through a lens with a focal length 1.5 times more, ie, about 50 mm. However, the focal length does not change! Changing the viewing angle. d3100 That is, you frame of 35mm should cut a piece of the picture. This is what you see on the DX-camera. And vice versa - if you're accustomed to using 50mm lens on a DX-camera by screwing it to the same FX, the frame you like to move apart, not the focal length change. Changing the focal length equivalent Zoom in / facility, but nothing that you will not find. Here is an example:
I made 2 frames and then combined in Photoshop and separated the brightness for clarity. One shot mode FX (35mm), another - DX. Apparently, no change in focal length occurs. If in a nutshell, the focal length - the distance from the center of the lens to the sensor. It is clear that it will not change and if the lens is the same, and only change the size of the sensor. Who in words is not clear, you can see the video:
Confusion with a focal length arises from the fact that the illusion approximation. It cut a piece of the frame is stretched to fill the screen. This is analogous to the "digital zoom". You compare 10x15 photo printed with a picture of a 35mm photo of the same size, printed with a picture DX and it seems that the second d3100 print objects closer. Yes, they are close, but not by changing the focal length, and due to the fact that a piece of the frame was cut and stretched to 35mm frame size.
Why is it important that does not change the focal length and angle of view? Because the focal length affects many things. For example, when you change the focal length is changing the depth of field. None of this happens d3100 if you have removed the lens from 50mm DX and nachepyly on FX. Depth of field remains the same. In addition, changing the focal length change and composition frame.
What are the benefits FX, for which we pay the money? Due to the large size, the sensor gets rid of digital noise at high ISO. If soap dish noise visible at ISO 400, then the FX-chamber you barely hover to see him on ISO 3200. In low light conditions, such as indoors, it is critically important and Permissions