Obtaining a blurred background

[Rancor]

So I'm pretty sure I get how to do this, but I want to verify what I think I understand.

To get a blurred background or boka I think is what its called, I want both a large aperture (1.8 or 1.4) and a short distance between my lens and my target/focus.

For a detailed background I want a smaller aperture (11 or 14) and a longer distance between my lens and my target/focus.

Does this sound about right.

 

[480sparky67 66]

You got it! [FONT=&quot]

[/FONT]Focal length is also part of the equation. Wide lenses make it very hard to get an OOF background, while long lenses it's pretty much mandatory.[FONT=&quot]
[/FONT]

 

[Big Mike]

Yes, you are on the right track.

The effect you are after can be achieved (is a result of) a shallow Depth of Field (DOF). The term Bokeh, is usually used to describe the aesthetic quality of the blur...not just that it's blurry. So you might say that a particular lens gives a more pleasing bokeh than another.

The way we control the DOF in our images is mainly with the aperture of the lens. Larger apertures (lower F numbers) will give you a shallower DOF.
Also, the focal length and the distance to the subject play a part. A longer lens gives you a more shallow DOF, but it may require you to back up further from your subject (which increases your DOF). Getting closer to your subject will make your DOF more shallow....but if you have to use a shorter focal length (wider zoom), then it's a trade off.

Also, the degree to which your background (or foreground) are out of focus, will be determined by how far they are away from your subject (focus point). So if you put your subject 5 feet in front of some trees...you may have a hard time getting the trees blurry. But if you put your subject 50 feet in front of the trees, it's much easier to get them blurry in the photo.

 

[thierry]

Bokeh*

 

[thierry]

^ annnd I just seen Big Mike beat me to it he is never a day late or a dollar short

 

[480sparky67 66]

If you're running Windows, download DOFMaster and you can play round with it at your leisure. You can change your lens (focal length), f/stop and focus point and see what would be in focus and what will not.
​

 

[Stradawhovious]

There are 4 factors in controlling DOF three of which you can control, and one you can't outside of purchasing new equipment........ aperture, distance from subject, and focla length are the ones you can control.... and sensor size is the one you can't.

I did a photographic representation of the ones you can control here. http://www.thephotoforum.com/forum/...-forum-photo-gallery/240559-2-8-vs-4-5-a.html

Hope it helps.

Also, Bokeh is not a function of technique, it is a function of the lens. It simply refers to the visual quality of the out of focus areas of a photograph, not the fact that it is out of focus.

 

[Rancor]

Thank you all very much. I definitely understand now.

 

[KmH]

Also, the focal length and the distance to the subject play a part.

Also, the degree to which your background (or foreground) are out of focus, will be determined by how far they are away from your subject (focus point). So if you put your subject 5 feet in front of some trees...you may have a hard time getting the trees blurry. But if you put your subject 50 feet in front of the trees, it's much easier to get them blurry in the photo.

To clarify what Mike says, a longer focal length at the same aperture and image scale in the frame, doesn't actually make the DOF any shallower. To maintain image scale with a longer focal length, the camera to subject distance has to increase.

The longer focal length, and increased subject distance, makes the background appear closer to the subject. (It's called background compression, or perspective compression.)

The background compression makes the blurred background elements larger in the image, making them seem more OOF from shallower DOF, but they aren't really.

Eye Shutter 2 Think: Photography Lesson 3

 

[Rancor]

Thanks a lot everyone. I am almost definitely going to post my first set of 4 tonight, maybe 2 sets. They will probably be junk, but I'm happy starting with junk. I am going to try lightroom 3, but it will be my first attempt and I'll basically just be mimicking common practices and touch ups I've seen in tutorials.

 

[Rancor]

good write up. Also good rundown on the use of bokeh.

It appears that most people (my self included till now) use it like "I'd like a more color". When they should be using it like this "I'd like a more mellow color" or "I'd like a more dramatic color"

 

[KmH]

Bokeh is a function of lens design.

The quality of bokeh is determined by the number and shape of the aperture blades, and optical qualities of the lens elements used and of the coatings used on lens elements.

Jarring, nervous appearing bokeh is produced from few apertures blades having shape edges, like Canons inexpense 50 mm f/1.8 II lens. It only has 5, sharp egded aperture blades. By comparison Nikons inexpensive AF 50 mm f/1.8D has 7 rounded egde aperture blades, and Nikon's AF 85mm f/1.4D "Cream Machine" has 9 round edged aperture blades.

By the way, there are 2 distinct types of bokeh:

1. Cream cheese
2. Hollywood

 

[KevinPutman]

I just take the picture into Photoshop and Gaussian blur the background out =p

 

[enzodm]

I just take the picture into Photoshop and Gaussian blur the background out =p

with a distance map, or equal everywhere?

 

[KevinPutman]

I just take the picture into Photoshop and Gaussian blur the background out =p

with a distance map, or equal everywhere?

Right now, I'd do equal everywhere, then erase (very low opacity brush) to give some depth, depending on how drastic I wanted the Bokeh.
The picture in my signature of the dandelion uses that effect. I just Gaussian blurred the entire background equally.