Discussing FX and DX sensors

Discussing Various Camera Sensor Formats


DX, full-frame, APS-C, FX, crop factor, 24×36, image circle.


Back in the film days, the rectangle that captured the image on a standard SLR (the film) was one size: 24mm x 36mm. That was all there was to it, and nobody really gave it a second thought. Later Kodac introduced 110 film cassette and Cameras which had a very small negative which was as small as 13mmx17mm.

Every camera manufacturer keeps its hardware and equipment slightly different from the competition; even models from the same manufacturer are different. People usually refer to a sensor’s size by its “crop factor.” That’s the number you use to find the 35mm equivalent of a given lens. It’s just like taking the middle of an image and throwing away the outside edges. If a sensor is 24mm x 36mm, then there is no crop factor, since it covers the same area as 35mm film.


Nikon has two different sensor sizes: full frame (FX) and 1.5x (DX).

Canon has three sensor sizes: full frame, 1.3x and 1.6x.

Other manufacturers are in the same range, with Olympus being the notable exception, at 2x.


Some people don’t like the term “full frame” because it isn’t specific. Full compared to what? For the sake of simplicity, when I say “full frame” I mean a sensor that’s roughly 24mm x 36mm.

That’s all well and good, but why should you care? Sensor size is important when you’re trying to pick a camera because full frame sensors have distinct advantages and disadvantages in different situations.

In general, full frame sensors have better image quality across the board, but they really shine when it comes to high ISO performance.

Take a look at the Nikon D300s and it’s full frame sibling the D700. The D300s is widely considered to be pretty good in low light, but the D700 is much better. In the real world, D700 gives a photographer 3 full stops of useable ISO over the D300s; One can shoot at ISO6400 on the D700 where he wouldn’t shoot above ISO1250 on the D300s. This has a lot to do with the size of the sensor. Both cameras have 12 megapixels, but the individual imaging sites on the D700 are farther apart, giving you a cleaner image.

Full frame sensors also give photographers more options when it comes to wide-angle work as your 14 mm lens works at 14 mm and not 21 mm (as in DX Body).

The downside is that FX sensors and lenses are bigger than their cropped counterparts. FX bodies are also more expensive because the FX sensors are about 20 times costlier than DX sensors. More so as the manufacturers load the FX Camera bodies with additional features and controls than DX bodies as they are already costlier so normally professional buy these.

There are also many situations where the crop factor helps you. I like having a little bit of extra reach with my long lenses and would not want to give that up easily as it gives me an edge in some kinds of photography like bird photography and also sometimes in clicking wild life when the subject is not so close.

Crop Sensor vs Full Frame Sensor: Choosing Which is Right For You

After you figure out the difference between a crop i.e DX sensor and a full frame FX sensor, you’ll need to decide which one suits your needs.

For the average consumer, a smaller 1.5x or 1.6x sensor should be fine. If you’re the kind of person who has the 18-55 kit lens and maybe one other lens, it just doesn’t make sense to spend the extra money on full-frame.

If you have lots of glass from the film days, it might be worth looking into a full frame body. Modern Nikon bodies are compatible with nearly every lens Nikon ever made, and Canon bodies all work with EF glass.

Photographers who enjoy shooting landscapes and architecture will definitely want to check out a full frame body (if they don’t already have one). Full frame image quality and wide-angle options are far-far better than their cropped siblings.

If you like shooting in natural and available light, you’ll definitely want to check out a full frame body too. As a FX lens can shoot on ISO in north of 5000 without worrying about excessive image noise, and one has more options when it comes to using (or not using) strobes and artificial light.

For nature, wildlife and sports enthusiasts, it might make more sense to stick with a smaller sensor. You can take advantage of the crop factor to get maximum detail at long distances.



Neeraj Garg