Do 50mm and 85mm lenses differ only by how far you stand from the subject?
Asked 8/15/2011
2 views
2 answers
0
If I compare a 50mm f/1.8 and an 85mm f/1.8 of similar optical quality, is the main difference simply my distance from the subject? In other words, can I replace one with the other by stepping closer or farther away, or by cropping? I’m especially interested in how focal length affects perspective, framing, depth of field, and background blur for portraits.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
15y ago
2 Answers
9
Perspective is a function of distance, not the angle of view of the lens. You could crop an image taken with a 50mm lens and get the same result as using an 85mm lens, but walking closer with the 50mm would give your shot a different perspective.
The whole scientific answer I'm not qualified to give, but there is a Wikipedia page on this subject: http://en.wikipedia.org/wiki/Perspective_distortion_(photography)
Originally by user2228. Source · Licensed CC BY-SA 4.0
user2228
15y ago
0
Generated from our catalog & community — verify before relying on it.
Not exactly. The key point is that perspective is determined by camera-to-subject distance, not by focal length itself.
If you stand in the same spot, a 50mm image can be cropped to match the framing of an 85mm image, and the perspective will be the same. What changes is field of view, and cropping throws away image area.
If instead you move closer or farther to keep the subject the same size in the frame, perspective changes because your distance changes. That’s why a closer 50mm portrait can make facial features look more pronounced, while an 85mm portrait is often considered more flattering: you usually stand farther back.
Depth of field and blur are also not identical. From the same position and same f-number, the 50mm will give greater depth of field than the 85mm if you crop to match framing. If you move closer with the 50mm to match framing, depth of field becomes very similar, but the 85mm still tends to give stronger background blur.
So: same position = same perspective; different focal lengths mainly change framing. Changing distance changes perspective.
Recommended products
UniqueBot
AI15y ago
Your Answer
Related Questions
35mm vs 50mm on Sony a6000: can I just step back with the 50mm?
Does an 85mm lens give more background blur than a 50mm if framing stays the same?
Does background blur change with focal length when subject framing stays the same?
Which lens is better for sharp full-body portraits on full frame: 50mm f/1.8 or 85mm f/1.8?
Why do telephoto shots seem to “flatten” or compress a scene?