How DX and FX lenses behave on DX and FX Nikon bodies
Asked 8/17/2012
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I’m looking for a clear reference for what changes when you mix Nikon DX and FX lenses with DX and FX cameras. Using a 100mm lens as an example, what happens to field of view and image coverage in each case?
- 100mm DX lens on a DX body
- 100mm DX lens on an FX body
- 100mm FX lens on a DX body
- 100mm FX lens on an FX body
I’m especially trying to understand the difference between focal length, crop factor, field of view, and why an FX body may reduce resolution when using a DX lens.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
2 Answers
6
Things get much easier if you forget about millimetres and focal lengths and talk about angular field of view.
If you have a '100mm' DX lens what happens when you:
Use it on a DX camera.
You get a horizontal field of view of 13.5 degrees (corresponding to 150mm on a full frame sensor)
Use it on an FX camera.
You get strong vignetting, or your camera crops the image reducing the resolution to 44% of the pixels leaving you with a horizontal field of view of 13.5 degrees (corresponding to 150mm on a full frame sensor)
If you have a '100mm' FX lens what happens when you:
Use it on a DX camera.
You get a horizontal field of view of 13.5 degrees (corresponding to 150mm on a full frame sensor)
Use it on an FX camera.
You get a horizontal field of view of 20.4 degrees (corresponding to 100mm on a full frame sensor)
Here's the same information in a handy table:
+---------------------------------------------------+
| | FX sensor | DX sensor |
+---------------------------------------------------+
| FX lens | 100mm equiv fov | 150mm equiv fov |
| DX lens | 150mm equiv fov* | 150mm equiv fov |
+---------------------------------------------------+
*when used in crop mode, otherwise the lens will vignette a certain amount and the usable field of view will depend on the particular lens, zoom setting, aperture and focus distance.
Originally by user1375. Source · Licensed CC BY-SA 4.0
user1375
14y ago
0
Generated from our catalog & community — verify before relying on it.
The focal length does not change. A 100mm lens is always a 100mm lens, regardless of the camera body. What changes is the field of view and, with DX lenses on FX bodies, whether the lens covers the whole sensor.
For Nikon’s 1.5× crop:
- 100mm DX lens on DX body: works normally; field of view is like a 150mm lens on full frame.
- 100mm DX lens on FX body: the lens usually does not fully cover the larger sensor, so you’ll either get strong vignetting or the camera will crop to DX mode. In crop mode, the field of view is still like 150mm on full frame, but resolution drops because only part of the sensor is used.
- 100mm FX lens on DX body: full coverage, but the smaller sensor crops the image, so the field of view is again like 150mm on full frame.
- 100mm FX lens on FX body: full coverage and the normal 100mm full-frame field of view.
So the key idea is: crop factor changes field of view, not focal length. Using a DX lens on FX mainly affects image circle coverage and may force a lower-resolution crop.
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AI14y ago
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