Question about bokeh

my 2 cents...

Sometimes kit lens with 3.5 to 5.6 does not give good bokeh, because aperture range. Definitely you should get better result with 50mm 1.8 @ f1.8. Also you can try using

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

I hope this helps
Ray

The affect is usually more pronounced with faster apertures, closer focus, longer lenses. At wide angle, you'll have a tough time developing much bokeh unless you're focused very close and there's some separation between subject and background. The online calculator Ray shared can help you see how focal length, subject distance, and aperture setting combine for depth-of-field. Certainly the kit lens can control depth-of-field to an extent, but is somewhat more limited in this respect than faster, longer glass.

...and the kit zoom probably focuses closer than that 50/1.8 as well, something else to consider.

This was taken at f/4 .

Pentax K10D + Pentax-A 70-200/4 @f/4

And this was taken at f/10 :

Pentax K10D + Pentax-A 35-70/4 @f/10

Congrats on the new camera.

At the risk of complicating things, there are really three different things operating here: depth of field (DOF), background blur, and bokeh.

DOF is the easiest of the three. DOF is a function of the aperture: the wider open the lens, the shallower the depth of field. A slow lens does not open as far, so it does not achieve as narrow a DOF. So as Ray says, you can get narrower DOF with your new 1.8.

Now, background blur. This is a constant source of confusion. A longer lens has a different perspective than a short one. The long lens compresses the background, while a short, wide angle lens spreads it out. Therefore, given the same DOF, the background will look blurrier with a longer lens if you change your position so that the image size is the same. (there is a nice, if detailed, explanation of this at http://toothwalker.org/optics/dof.html). This is the source of the widely accepted misconception that longer lenses have shallower DOF. For the most part, they don't. But if all you are concerned with is blurring the background, the effect is the same: the more you zoom out, the blurrier the background will be, for a given field of view--that is, if you stand farther back to get the same size image in the viewfinder with the longer lens.

Finally, bokeh. this usually refers to the quality of the out of focus area. For example, you will find people talking about "smooth" or "buttery" bokeh. This is a property of the lens, including the design of the aperture leaves.

So what does all this boil down to? Unless you are in the market for a new lens, forget about bokeh. If you are using a zoom and have room to move back, you can zoom out as much as possible to increase background blur. Regardless of that, open the aperture up to decrease DOF. (However, most lenses are fairly soft opened all the way up, so if it is a picture where you really want to maximize sharpness, you might sacrifice a little on the DOF side and close the lens down a little.)

The concept of bokeh is often misunderstood by new photographers, in part because so many other photographers on the internet make statements based on erroneous interpretations. As Dan Koretz notes in his comments, shallow depth of field and bokeh are two different but somewhat related issues. Rather like water being wet (comparable to DOF), while describing the water temperature as "comfortable" or "uncomfortable" (or hard vs. soft at extremes of temperature) depends on ones personal comfort level (comparable to bokeh).

My usual advice is to go straight to the source: Google Mike Johnston and bokeh . Or just click on that sentence and read the related links. Mike didn't invent the concept of bokeh, but he's responsible for popularizing it in the US. Talking about bokeh without referencing Mike Johnston is like talking about the Zone System without referencing Ansel Adams.

"Boke" is a Japanese word describing the qualities of "out of focus" areas of a scene. It is especially noticed in highlights (bright areas).Boke can either be smooth, or harsh and disturbing to the eye.

Interestingly I never heard of Mike Johnston? I have however read several of Prof. Merklinger's tomes about "Boke". And in my mind, he is the name associated with the term.

If memory serves (and it doesn't as reliably as it used to), Mike Johnston began writing about "boke" sometime back in the 1990s in a magazine he edited or wrote for. He coined the "bokeh" spelling for the convenience of a Western audience to convey something closer to the correct pronunciation, probably guessing that without some help Westerners would pronounce it like the soft drink "Coke". Stephanie's use of the spelling "bokeh" indicates that Johnston's variant won out over the alternatives long ago, so it's moot.

I do recall the earliest online discussions - pre-web and very early web days - about "bokeh" used Mike's spelling and usually referred to Mike's articles. This was on CompuServe, even before it was absorbed by AOL Online, and on newsgroups.

Web chatter popularized the concept even further to a new audience. Not just a new audience of online participants but a new group of photographers just getting into the hobby. Unfortunately, popularization of the term did not also carry popularization of a complete understanding of the concept behind the term. Hardly a week goes by on photo.net - or a day somewhere online - without a discussion either about or referring to bokeh, many of which tend to perpetuate myths and misunderstandings.

For example, the original poster's comment here (not to imply any criticism of your perfectly legitimate question, Stephanie)...

"I read about bokeh but could not seem to achieve it while using aperature priority mode."

...indicates that while there's plenty of talk about bokeh online, there clearly isn't enough straightforward, factual information to dispel the disinformation and jibber jabber that tends to confound every new photographer who hears about the term. Stephanie appeared to understand that bokeh was somehow related to aperture, but not that it was unrelated to the metering or exposure mode. (Again, Stephanie, not criticizing you or your question, just using this as a convenient illustration.)

Among the more popular myths are that bokeh - the perceived quality or aesthetics of the out of focus areas - is determined solely by iris shape (hence the association with aperture, although the term "iris" more closely relates to the physical mechanism and shape of the aperture; while the term aperture seems to be used most often in reference to metering and exposure). And the related myth, that bokeh describes only the out of focus blobs of light. Consequently, many of the photos displayed that purport to prove the quality of bokeh tend to show only out of focus point light sources in the dark. Round blobs of light are presumed to equal good bokeh; multi-sided blobs are presumed to equal bad bokeh. And I suppose that's fine if most of your photography involves bars, candlelight dinners and similarly romanticized settings.

But the shapes of blobs of light are only half the picture. Some photographers are more concerned about the rendering of out of focus lines and edges. Nature photos, landscapes and wildlife photos are more likely to involve these - grass, twigs, tree limbs, etc. - than blobs of light at night. And while a fast lens used wide open will typically render a nicely rounded blob of light at night, it may not necessarily deliver smooth rendering of out of focus straight lines and hard edges. My old Vivitar Series 1 70-210/2.8-4 zoom used wide open will deliver nicely rounded blobs of light, if I was interested in taking photos of out of focus blobs of light. But the bokeh is harsh for nature photos, with unpleasant doubling or multiple images around OOF edges (nisen-bokeh) of foliage, twigs, branches, grasses, etc.

And now I'm guilty of perpetuating even more jibber jabber. There's already tens of thousands of words about bokeh online.