How can I get very large bokeh while keeping a nearby subject in focus?

Asked 12/22/2016

3 views

2 answers

0

I want to create portraits where a person is sharp but nearby Christmas lights turn into very large blurry circles. I tried a 50mm lens at f/2.8, but when the lights and the face seem close together, I can’t get that same effect. Is there a specific technique or term for this, and what camera/lens setup helps produce it?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

9y ago

2 Answers

7

For the first photo example: Longer focal length and/or wider aperture are needed. 50mm and f/2.8, especially if used on an APS-C camera, won't give that kind of bokeh that close to the focus distance. It looks to be something more like an 85mm f/1.2 on full frame with the (more or less) in focus subject at or near minimum focus distance.

Ignoring the two large round bokeh balls for a second (more on that in a bit), the lights with the largest "cats eye" shaped bokeh balls also appear to be quite a bit closer to or further from the camera that the lights with smaller bokeh that are closer to the same distance from the camera as his face.

"Cat's eye" bokeh is the result of using a very wide aperture lens where the entire entrance pupil is not visible from the angle of the widest light rays in the field of view. This results in the bokeh being vignetted into an irregular shape. The closer to the edge of the field of view the light source is, the more pronounced the distortion of the bokeh shape will be. Highlights coming from light sources near the center of the FoV will be round or nearly round because the entire entrance pupil is visible on the front of the lens from their position. Stopped down the same lens will not demonstrate the effect even for the edge rays. If a lens is designed with uncorrected field curvature, spherical aberration, or astigmatism this can make the cat's eye effect even more pronounced and/or swirly.

enter image description here

Based on the orientation of the direction of the "cat's eyes", which will always be tangent to the center of the lens, it appears the photo was taken with the very large bokeh ball in the exact center of the frame, then cropped to make it off center. Or it may be that the two large round bokeh balls were added in post from a different exposure. The more I look at the photo and the shape and position of the rest of the highlights bokeh, the more I am inclined to take the second view.

Then again, it might have all been done with post-processing.

In the second photo: The string of lights is much closer to the camera at the bottom of the frame than the other end of the string being held by the subject. Imagine the photographer holding the near end of the string of lights at waist level or maybe even chest level while the camera is at eye level. The top light is the out of focus and blown out moon.

Originally by user15871. Source · Licensed CC BY-SA 4.0

user15871

9y ago

0

AI Answer

Generated from our catalog & community — verify before relying on it.

To get that look, the lights cannot be at exactly the same distance as the subject. Focus is sharp on a plane; objects noticeably in front of or behind that plane become blur circles.

For larger bokeh, you generally need:

  • a wider aperture (f/1.8, f/1.4, f/1.2)
  • a longer focal length (for example 85mm rather than 50mm)
  • the subject close to the lens, often near minimum focus distance
  • the lights either closer to the camera or farther behind the subject than they appear
  • a larger sensor can help compared with APS-C

Your 50mm at f/2.8 usually won’t produce such extreme blur at close distances, especially on APS-C. The first example likely uses something like a fast short-telephoto lens on full frame. The “cat’s eye” shaped highlights come from using a very wide aperture near the edges of the frame.

So the key is not a special trick: it’s shallow depth of field plus careful spacing between camera, subject, and lights.

UniqueBot

AI

9y ago

Your Answer