Camera selection can affect the focal length (Nikon)

It's not just the lens' focal length that affects how large a field of view you can achieve. Different lenses may display different image angles on different cameras. The same goes for brands and camera manufacturers.

Imagine you have the lens Nikon 50mm f/1.8 D.

This lens has a fixed focal length of 50 mm, ie you can not zoom in or out. We will now do a test on how the choice of camera can affect the focal length.

We use in the test of three different digital system cameras.

Nikon D700 Nikon D90

We set up some miscellaneous things on a kitchen table, put the camera on a tripod and take some cards.

If we use the lens on your Nikon D700 so it gives the picture below. Note that there is a lot of air around the various objects.

If we now, without moving tripods etc, change camera to your  Nikon D90 we get the picture below. The air around the various motifs is now completely gone and both the dachshund and the clown have been cut.

By changing the camera, we got the same effect as if we had zoomed in on a lens.

Since the lens we used was a fixed optics, without the possibility of zooming back or forth, we wonder - how can it be that we got two different results with two different cameras?

The size of the camera's sensor affects the camera's field of view through the lens

Each digital system camera has an image sensor that digitally detects the image and the flow of light traveling through the lens into the camera. In the older, non-digital, the cameras were, for example, 35 mm film and the digital sensor today fulfills the same function.

The images above could differ depending on how large the digital camera's image sensor is.
An older system camera's classic 35 mm film had the dimensions 36.0 x 24.0 mm, but if you compare with e.g. Nikon D90 so it has an image sensor that measures 23.6 x 15.8 mm. The sensor in the digital system camera Nikon D90 has a size equivalent to 50% of its analog predecessor.

Most lenses on the market are adapted for use with both older film cameras and newer digital cameras. Although the lens in its shape is round, it has a rectangular work surface inside. As you can see below, our three different cameras have different sized sensors, all marked in red below. These sensors should be the camera's eyes and look through the lens.

Nikon D700 Nikon D90

The lens is the same size all the time, of course, but when we move the lens from one camera to another, the camera is what is looking through the lens. The camera's image sensor is the eye and controls how much each camera sees through the lens.

Nikon D700 Nikon D90

The different sensors in the cameras thus see different amounts of the image, therefore the end result also varies. A smaller sensor sees less of the subject. From what the camera sees, the camera creates its image and the camera does not see the clown's entire hat or tail on the dachshund, well then it is not included in the image either. The images are thus cropped already inside the camera, before they are taken, if the sensor is smaller.

Nikon's different sensor types

There are two different sensor types in Niko's cameras and the different sensors are different sizes.

Sensor Dimensions (Crop factor)
FX (Fullformat) 36 x 24 mm
DX (APS-C) 23.7 x 15.5 mm (1.5x)

Crop factor

With digital cameras, people talk about something called a crop factor or in English 'crop factor'. The crop factor indicates how much smaller the digital camera image is. In the fall Nikon D90 is 1.5x, because the analog size of the analog camera is 50% larger than the sensor in Nikon D90.

Crop factor = Perceived focal length extension

Since we get the effect of zooming when the sensor becomes smaller, we talk about focal length extension. The image angle and focal length you get with the Nikon D700 and Nikon 50mm f / 1.8 will be basically the same as you get with the Nikon D90 and Nikon AF 35mm f / 2 D, because you then multiply 35 by 1.5 and get 52 mm. < br>
Below you can see the focal length extension that applies to these two camera models, which represent Nikon different sensor types.

Nikon D700 Nikon D90
FX , Full frame DX sensor
No focal length extension Focal length extension 1.5x

Why is all this important to me? How does it affect me in practice?

As we talked about earlier, by changing the camera, we got the same effect as zooming. With different cameras, we got a perceived change in focal length. Therefore, the focal length of an objective is not always what it appears to be. A lens and a focal length of 50 mm can suddenly become 75 mm, depending on the camera used.

If in the past you had a Nikon analog camera and a wide-angle lens, this lens may not be experienced in the same way when you then use the lens on your newly purchased Nikon digital camera. The wide viewing angle may be perceived as narrower and this is not because the lens' properties have changed, but because the cameras work in different ways. You must therefore be aware and prepared for the effect of the choice of camera on the focal length of the lens before buying a new lens or camera.

Lensora will help you

On Lensora.com, we always calculate the perceived focal length for you, so that you can see how much the perceived focal length is on your particular camera when you look closer at a lens.