Does a crop sensor change perspective, background compression, or depth of field?
Asked 5/16/2013
3 views
2 answers
0
I understand that longer focal lengths can make subjects look more "flattened" or compressed, and that crop sensors have a narrower angle of view than full frame with the same lens. For example, a 35mm lens on Nikon DX gives a field of view similar to about 50mm on FX.
What I want to know is: does the smaller sensor itself change perspective or the apparent flatness/compression of objects, or does it only crop the image?
For example, if I use a 35mm lens on both DX and FX, from the same camera position, will perspective be different? And why do people say crop sensors affect depth of field?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
10
Foreshorntening (the technical term for the effect of "flattening" objects) is determined by subject distance only, not focal length.
When using a wide angle lens if you are the same distance from your subject as you would be when shooting with a portrait lens, you'll get the same flattering effect, only your subject will take up less of the image.
A crop (DX) sensor will therefore produce exactly the same flatness of objects as a full frame (FX) sensor, provided subject distance remains the same. Furthermore if the full frame lens is 50% longer than the crop lens and has the same size entrance pupil then field of view and depth of field will be the same, thus the two images will be virtually indistinguishable.
Originally by user1375. Source · Licensed CC BY-SA 4.0
user1375
13y ago
0
Generated from our catalog & community — verify before relying on it.
A crop sensor does not change perspective or "flattening" by itself. Perspective (including foreshortening/compression) is determined by camera-to-subject distance, not sensor size.
So if you use the same 35mm lens from the same position on DX and FX, the perspective is the same. The DX camera just records a narrower field of view — essentially a crop of the center of the image.
Where people get confused is when they compare equivalent framing. To make DX and FX pictures look similarly framed, you usually either change focal length or move the camera. If you move farther away, perspective changes because distance changed, not because of the sensor.
Depth of field can also be made equivalent between formats when you match field of view and entrance pupil; in that case the images can look very similar. But with the same lens at the same distance, the main sensor-size effect is angle of view, not perspective.
Recommended products
UniqueBot
AI13y ago
Your Answer
Related Questions
What are the pros and cons of using FX lenses on a DX Nikon body?
Can I get the same 85mm full-frame look on DX by stepping back with an 85mm lens?
Do DX/APS-C lenses use their actual focal length, and do you still apply crop factor?
Will a 35mm DX lens on Nikon DX give the same view as a 50mm FX lens?
How DX and FX lenses behave on DX and FX Nikon bodies