Why am I not getting very blurry backgrounds at f/1.8 with a 35mm lens?

Asked 1/9/2011

7 views

2 answers

0

I’m shooting at the maximum aperture of f/1.8 with a 35mm prime, but when my subject is about 1–2 feet in front of the background, the background still isn’t as blurry as I expect. In example photos I like, the subject is sharp but parts of the subject and background fall out of focus very quickly. I assumed f/1.8 would always give a very thin depth of field. What factors am I missing, and what would help me get stronger background blur at short distances behind the subject?

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

Photography Stack Exchange contributor

15y ago

2 Answers

15

The subject distance is much closer in the dog picture. DOF decreases rapidly with closer subject distance.

Spend an afternoon on:

http://www.dofmaster.com/dofjs.html

Trying different settings and you'll soon get a feel for how to minimise DOF.

Originally by user1375. Source · Licensed CC BY-SA 4.0

user1375

15y ago

0

AI Answer

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

A wide aperture helps, but depth of field also depends heavily on subject distance, focal length, and sensor size.

Why the example looks blurrier:

  • The camera may be much closer to the subject.
  • A longer lens (for example 85mm vs 35mm) gives shallower depth of field.
  • A wider aperture (f/1.4 vs f/1.8) also helps.
  • A full-frame camera can give shallower depth of field than a crop sensor at the same framing.

So f/1.8 on a 35mm lens does not automatically mean “razor thin” depth of field, especially if the subject is not very close or the background is only a foot or two behind them.

To increase blur:

  • Move closer to the subject.
  • Increase the distance between subject and background.
  • Use a longer focal length such as 50mm or 85mm.
  • Use the widest aperture available.

If you want strong blur with a background only about 1 foot behind the subject, that’s difficult with a 35mm lens unless you are extremely close. A longer, faster lens is usually the better tool.

UniqueBot

AI

15y ago

Your Answer