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I am taking 2 pictures using:

  1. Nikon D3400 APS-C sensor and an APS-C kit lens, 18-55mm set at 50mm
  2. Nikon D850 full frame camera and a full frame lens 50mm that is designed for full frame Nikon camera

Both systems have lenses mounted on them that is specifically designed for them. I am NOT putting FF lens on APS-C camera nor I am putting APS-C lens on FF camera.
Shouldn't both 50mm images taken by above 1 and 2 have same field of view?
What am I not getting here? Please clarify.

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  • Has this Q been asked before? (Will search for duplicate later.) In mean time, FOV will be different for lenses with same focal length, but different sensor sizes. – xiota Dec 9 '18 at 8:24
  • This answer is concerned with perspective rather than field of view, but the two are closely related & one explanation does cover both, so have a look & see if it goes some way to explaining - photo.stackexchange.com/a/97747/57929 – Tetsujin Dec 9 '18 at 8:42
  • Why is there so much confusion about this? A 50mm lens is a 50mm lens. It is the smaller sensor that affects the field-of-view. (Caveat - "designed for APS-C" lenses additionally have a smaller image circle, but it's not necessary to know that to understand the overall concept.) I really think some company, with the resources in animation, needs to make a YouTube video explaining this. – osullic Dec 9 '18 at 13:32
  • Closely related: Focal length on Full frames and cropped sensors – scottbb♦ Dec 9 '18 at 18:14
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    This question has been asked/answered in nearly endless forms here. What about the previous questions/answers do you not understand? – Michael C Dec 9 '18 at 18:29
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The two lenses project the very same image in the focal plane. The FF camera just takes a wider sample of the image because its sensor is larger. In other words, the APS-C image is exactly the center of the FF image (cropped 20-25% on all sides).

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In your example, both 50mm lenses will have a similar circular image projection, but what changes is how much of that projection is used by the image sensor. APS-C lenses generally have a slightly smaller image circle but the size is not always consistent.

What is more important here is the size of the sensor.

The larger sensor of a Full Frame camera will see more of the image than the smaller sensor of the APS-C “crop” camera.

It is this "crop" that changes the field of view in the final image.

Bob Atkins: Full Frame vs APS-C “crop” enter image description here

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  • Well in this video youtu.be/LxZe4MuM8_Q it says that APSC lenses for APSC cameras have a smaller circular projection. If you put FF lens on APSC camera then it may crop but APSC lenses for APSC sensors does not crop as it already projects a smaller image. So this video says 35mm apsc lens on apsc camera and 35mm ff lens on ff camera will produce an identical image. Only will the image be zoomed up if I put ff lens on apsc camera. Am I right? Can you please watch the video. And thanks for the previous reply – Fardan Hasan Dec 9 '18 at 11:45
  • It doesn't need the video - this is to be expected. An APS-C lens projects a smaller circle, which makes it cheaper & easier to manufacture. If you put it on a FF camera you will get a dark vignette ring beyond that area. FF lens on APS-C just gets cropped, so you can't see what's missing. – Tetsujin Dec 9 '18 at 12:31
  • @FardanHasan The larger image circle of the FF lens contains a wider field of view than the smaller image circle of the APS-C lens. The center of the FF image circle that is the same size as the APS-C image circle contains the exact same field of view as the APS-C lens' image circle. The extra part of the FF image circle that is larger than the APS-C image circle contains things that are outside the edges of the smaller APS-C image circle. – Michael C Dec 9 '18 at 18:31
  • A comment on this answer... it hasn't been stated explicitly, but I think it should be, that in the schematic, where the blue shaded area represents a full-frame lens and the pink shaded area represents an APS-C lens, it should be assumed that the two lenses have the same focal length (i.e. the same figure engraved on the lens). – osullic Dec 10 '18 at 11:37

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