How do you get the blurry background effect?

[vintagesnaps]

To get that blurry background, open up the lens; but also adjust shutter speed/ISO since you're letting more light into the camera when you use a larger aperture.

You might need to reread those links Tomasko; the one from B&H says bokeh is more than blur, it's the aesthetic quality of it. The definition from Nikon says it's the pleasing quality of out of focus blur.

Setting up a shot maybe you could for example turn the subject around, or maybe that wouldn't work if there was lettering or other distraction on the other side, but my point is to the OP - look at what's there in the scene and in the background and think about how it's going to look before you release the shutter. Think about your vantage point, you can move and change the perspective and get something different in the frame.

Depending on the background, even if it's out of focus you could still have shapes or blobs of color or blurred lines and texture that may or may not look good. In the iris example (which is a beautiful photograph) it worked. It doesn't always work that well, it depends.

 

[photo1x1.com]

Bokeh refers to the "quality" of the blur (good or bad).

Anyway... the three things that go together to produce strong out of focus blur are:

1) LOW focal ratio adds to the blur
2) LONG focal length lens adds to the blur
3) CLOSE subject, distant background (if the background is very close to the subject then the difference in focus between subject and background won't be so strongly different.)

Many lenses are just not capable of producing a very strong blur. Most DSLR cameras come with a "kit" lens and it's usually something an 18-55mm zoom with a variable focal ratio which can be as wide as f/3.5 at the short focal length (wide angle) end, and f/5.6 at the long focal length (narrow angle) end. Unfortunately f/5.6 at 55mm will produce very little blur and likewise f/3.5 at 18mm will also produce very little blur. It's a struggle to get much blur out of these lenses unless you resort to extremes such as putting the subject at closest possible focus distance and putting the background very far away.

It's much easier to do with longer lenses.... 85mm and up and hopefully with a low-ish focal ratio (such as f/2 or lower). You'll even get a little blur with a 50mm lens and a low focal ratio (f/1.8 or f/1.4, etc.) but as you get to lower focal lengths it becomes very difficult to produce much in the way of a pleasing blur. I have a 14mm f/2.8 lens and that lens wants the whole world to be sharp almost no matter what I do. The most I can do is get enough blur to make it look like I just barely missed focusing accurately (the blur isn't strong enough to look intentional.)

As you get to much longer focal lengths (e.g. 200mm) then you can even get pleasing blur at f/4.

I have a 135mm f/2 lens which is basically a cream machine (LOADS of background blur) and a 300mm f/2.8 that produces so much blur that diabetics should not look the photos lest they go into insulin shock from all the sweetness! (Ok, I'm kidding... but just a little). The point is, LONG lenses with LOW focal ratios produce a LOT of blur when you have a CLOSE foreground subject and a DISTANT background (not close to the subject).

This is 300mm at f/2.8. In the (distant) background, there is a patio and people are having tea.

Do you see anyone having tea? Neither do I. But since I took the photo, I know that they were there. This is an example of extreme blur. Sometimes you don't want so much blur that the background is no longer recognizable. I have other photos where we specifically wanted soft blur on the background but wanted to make sure you could actually recognize the background subjects for what they were.... in those cases you back away from using the widest possible focal ratio and use something slightly narrower.

BTW, it is also possible to "fake" the background blur using products such as Photoshop.

The blur in this background is fake:

Here's the original (as shot):

In the original you can read the wine bottle ... Silver Palm (a very pleasant cabernet). But this was done for a restaurant who wanted the attention on the food -- and the wine is there to help support the mood. So we want a bottle (for the mood) and we want you to "recognize" the bottle... we just don't want you to be able to read the bottle.

To produce this, I had to use Photoshop using masks and layers... the top layer has a photoshop "lens blur" filter applied but the background does not. There's also a mask to let me selectively reveal the non-blurred plate of food through the "blurred" upper layer and I had to very carefully feather the blur out from around the edge of the plate to create a believable transition. It took a while to do.

The blur was also done to match the intensity of blur in other shots that were going to be used in the same articles.

So why not just shoot at the same f-stop using the same lens as the other images which had the correct "as shot" blur??

This was the only dish on a wide rectangular plate and composed at an angle. When I used the same f-stop as the other shots, the food (the main subject) was not entirely in focus the way we wanted. So we chose to stop down the lens to increase the depth of field, improve the overall look of the food and then "fake" the blur to match the rest of the photos in the shoot.

While I say it is possible to "fake" the blur (with an example), I have seen some really awful fake background blur. It took me several attempts to try to come up with a fake blur that could pass for natural blur (like all things in photoshop... it's a learning experience. )

Awesome iris image, Tim! I love it!

 

[Tomasko]

You might need to reread those links Tomasko; the one from B&H says bokeh is more than blur, it's the aesthetic quality of it. The definition from Nikon says it's the pleasing quality of out of focus blur.

I read them, that's why I'm saying bokeh isn't just that "nice smooth background blur" Designer mentioned.

 

[Ysarex]

One correction. The size of the sensor has nothing to do with depth of field. It is all about lens focal length and aperture as well as distance. Smaller sensor cameras tend to use shorter lenses so that is where this sensor size misconception arises.

I know what you are referring to, so yes and no. But using the same 85mm lens with the same aperture setting and the same crop of the subject with both full frame and crop sensor would result in a much more blurred background on the full frame image, because you are closer to the subject.

Lens focal length and aperture. Subject distance. Nothing else. You can use the 85mm lens at any subject distance. The sensor has nothing to do with it. You are saying that subject distance affects depth of field and, indeed, it does.

Sensor size is a DOF determinant. We've been through this before, but oh well... If you take the same photo with two different cameras having different size recording media, the photo from the camera with the smaller media (sensor or film) will have more DOF. Wolfgang has this one right.

This is the standard equation for hyperfocal distance:

where H = hyperfocal distance, f = lens focal length, N = f/stop and c = circle of confusion. The value for the circle of confusion is in part derived from the size of the sensor. Change the size of the sensor and the value for "c" changes. Change the value for "c" and "H" changes and that's a change in DOF. Therefore, changing sensor size changes DOF.

Joe

 

[bianni]

Why does a bigger sensor lead to a shallower depth of field?

 

[Designer]

The definition from Nikon says it's the pleasing quality of out of focus blur.

@Tomasko

I think Nikon might know something about it, considering the concept originated in Japan.

We can bastardize English 'till the cows come home, but the original Japanese is somewhat protected.

Unless you want to bastardize the Japanese language as well.

 

[Ysarex]

Why does a bigger sensor lead to a shallower depth of field?

That's a lot of confused people and wrong answers.

Joe

 

[SquarePeg]

I always was under the impression that the bokeh can be either pleasing or not. Bokeh is essentially the blur and we can add descriptors like creamy bokeh, harsh bokeh (that jittery hurts your eyes stuff that the cheaper lenses sometimes produce) and of course my favorite, bubble bokeh!

The Legend And the Bubble Bokeh. Review of the Meyer Optik Goerlitz Trioplan 100mm f/2.8

 

[Jamesaz]

I've always considered bokeh to be the way a lens transmits out of focus specular highlights. I could be way wrong though. It's happened.

 

[Tomasko]

@Designer, seems you didn't read the links. No problem, here are more examples for you once again. I can't believe I have to do this on a dedicated photo forum.

wikipedia
Differences in lens aberrations and aperture shape cause some lens designs to blur the image in a way that is pleasing to the eye, while others produce blurring that is unpleasant or distracting—"good" and "bad" bokeh, respectively.

bokeh Meaning in the Cambridge English Dictionary (notice the word "NICE" in the eaxmple, as adjectives are almost always used in conjuction with it)
a blurred (= not clear) effect used in photography:
This lens produces that nice bokeh in the background that looks great in portraits.

bokeh | Definition of bokeh in English by Oxford Dictionaries :

The visual quality of the out-of-focus areas of a photographic image, especially as rendered by a particular lens.

‘a quick, visual survey of the foreground and background bokeh of a variety of lenses’

• ‘Many buy this lens to escape the often poor bokeh of the Vega, but is it really better?’
• ‘Some folks feel the best bokeh has an undefined, blurred edge.’
• ‘For me, the 85 Prime's bokeh just feels easier on the eyes.’
• ‘It is easily light enough for a handheld supertelephoto lens, but what would the bokeh be like?’

It's not my definition or anything, this is a standardised term in photography as you can (hopefully) clearly see. It's everywhere defined as the blur and its visual quality, which can be nice/pleasing or bad. I don't know why you're fighting it.

 

[fmw]

Semantics are always hard to debate.

 

[petrochemist]

One correction. The size of the sensor has nothing to do with depth of field. It is all about lens focal length and aperture as well as distance. Smaller sensor cameras tend to use shorter lenses so that is where this sensor size misconception arises.

I know what you are referring to, so yes and no. But using the same 85mm lens with the same aperture setting and the same crop of the subject with both full frame and crop sensor would result in a much more blurred background on the full frame image, because you are closer to the subject.

But then you're changing one of the other variables listed. You can use the same lens from the same distance & at the same aperture. The FOV will be different but the DOF won't if the images are viewed in the same way (without cropping etc as printing bigger changes the circle of confusion).

 

[Ysarex]

One correction. The size of the sensor has nothing to do with depth of field. It is all about lens focal length and aperture as well as distance. Smaller sensor cameras tend to use shorter lenses so that is where this sensor size misconception arises.

I know what you are referring to, so yes and no. But using the same 85mm lens with the same aperture setting and the same crop of the subject with both full frame and crop sensor would result in a much more blurred background on the full frame image, because you are closer to the subject.

But then you're changing one of the other variables listed. You can use the same lens from the same distance & at the same aperture. The FOV will be different but the DOF won't if the images are viewed in the same way (without cropping etc as printing bigger changes the circle of confusion).

You're right that moving the camera invalidates the comparison but so does changing the FOV. To make a meaningful comparison the two different format cameras must be used to take the same photograph. Just setting up that "same photograph" comparison can create points for debate, but I think most would agree that the two photos should at least contain identical subject content. Should they both be made at the same exposure setting? Same aperture? When we use formulae to calculate DOF we use standardized variables. Then in taking the "same photograph" we should probably use those same variables -- in that case same f/stop for both photos as opposed to same physical aperture diameter since physical aperture diameter is not a standard DOF formula variable. Furthermore we should work with the industry standardized definition and assessment methods for DOF.

If we do that we arrive at the fact that I believe no one contests: The photo from the smaller format camera will exhibit deeper DOF. That's easy enough to test and prove and it's been done over and over and over.

The fact then that the photo from the smaller format camera has deeper DOF is right there plain to see. The standard industry definition for DOF and the formulae used to calculate DOF are consistent with what the above images show and since we have over 100 years of industry acceptance and reliance on those formulae, I for one vote we continue to use them and rely on them: they're proven. In examining those formulae we find that one of the required variables used in the calculations is a value that is in part predicated on the size of the sensor.

Joe

 

[Designer]

@Designer, seems you didn't read the links. No problem, here are more examples for you once again. I can't believe I have to do this on a dedicated photo forum.

It's not my definition or anything, this is a standardised term in photography as you can (hopefully) clearly see. It's everywhere defined as the blur and its visual quality, which can be nice/pleasing or bad. I don't know why you're fighting it.

You are not required to keep on bastardizing the English language. You can cease at any time.

I'm "fighting" for the language.

But heck, let's just see what would happen if I didn't choose to correct your thinking:

Aromatic garbage
Rap "music"
Military intelligence
Congressional action
Ugly bokeh

Considering the source and original meaning of the term; ボケ味, we see that there is no equivalent term for "ugly bokeh".

Just because lazy, ignorant Westerners have bastardized the term by stretching the original definition doesn't mean that the definition has actually changed. It only means that lazy ignorant Westerners have co-opted the term to mean something that it had not meant previously.

Yes, of course, I concede that I am vastly outnumbered by lazy, ignorant Westerners, and that common usage of the term now means any kind of blur that you want. Therefore I yield.

 

[SquarePeg]

Since we can't seem to play nice and disagree respectfully, let's get back to the topic that the OP was really asking about please. I don't think someone who needs to ask how to get background blur really gives two shakes about who is right in these other slightly off topic semantic arguments.