Full frame sensor versus cropped - Digital Cameras

There are many reasons why professional photographers prefer a full frame digital camera with a FF sensor over a cropped ASP-C camera. The first reason would probably be the fact that you can enjoy wider shooting angles. On ASP-C sensor, you have to multiply the range by the crop factor. For example, if you use a 14mm lens and you have a 1.5x cropped sensor, you will get 21mm from the lens, instead of 14mm. That means less wide range. With a FF camera, you don't have this "problem", a 14mm lens will be a 14mm lens. If you enjoy shooting images at the tele end, you can enjoy this multiplication on ASP-C sensors, because you get longer reach. For example, a 200mm lens on 35mm will become 300mm on a 1.5x cropped.

The main advantage for Full frame sensors over ASP-C is the physical size of the sensor. The larger the sensor, the larger the pixels/recording micro sensors.  Large pixels usually mean more dynamic range, better signal-to-noise ratio, better color accuracy and higher light sensitivity. All of those advantages should lead to a better image quality overall.

One very popular question on the web is whether a ASP-C sensor (cropped sensor) can perform as a full frame sensor. What we know is that larger sensors provide better image quality in general. Camera manufacturers keep improving the ASP-C sensors. Canon as minimized the gaps between the mini lenses in order to achieve mroe light gathering capabilities and therefore, improve the image quality in ASP-C sensors.



Full frame sensors are also built differently. Because the size of the sensor is larger compared to ASP-C (like in the Nikon D7000 camera), the wires which collect the data from the sensor are at the back of the micro sensors. In CMOS sensors, some of the wiring is at the front surface to save space. Because the surface is used for both the wiring and the recording pixels, micro lenses have to be used to redirect the light onto the photosensitive layer. So this is a somehow a big disadvantage for ASP-C CMOS sensors.  However, this is not the end of the story yet.

Backside Illumination (BSI) sensors have come to help solve many of the problems related to the CMOS sensor design.  The first back illuminated CMOS sensor was introduced in 2009, and many other manufacturers start embracing this technology. Apple used the back illuminated sensor on its latest iPhone mobile phone camera.  We won't get into too many technical details, what you should know is that technology can improve upon what we have today.

So back illuminated sensors could provide a partly solution to some of the problems that we have with small sensors. Even so, there is one thing that just cannot be solved, and that's the size of the photosensitive layer that collects the photons of light.  The larger the surface, the more light it gathers. If you can improve the light gathering capabilities of a smaller sensor, you can do it on a large sensor too.

After all this, you might think that FF sensors perform much better than ASP-C ones, but this is not the case. If you compare a mobile phone camera to a DSLR camera, the differences are huge. However, ASP-C sensors are not that much smaller than 35mm. In fact, when I've seen Canon 5D Mark II vs. Canon 7D or Nikon D700 vs. D300s comparison reviews, the differences were there, but not something that big. Full frame sensors cost more than cropped sensors. That means that in order to create cheaper DSLR cameras, cropped sensors are used. However, wait a minute, the price of FF sensors should have gone down by a large margin. Maybe it is a marketing trick that makes us pay more for FF cameras, when the price difference is really not that substantial?

I think that the FF sensor's price is just too high. Why people have to pay almost twice to get the Nikon D700 over the Nikon D300s? There are almost the same camera, the sensor is different, while the D700 is FF and the D300s is cropped.

I don't know what the future brings, but for now, if you want the best image quality, you should get a FF camera.