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09-13-2011, 01:51 PM - 2 Likes   #1
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Bokeh and Depth Of Field - Zeiss

Did you know that "Bokeh" is a Japanese word?

For those interested, I found this article about the topic.
Enjoy the reading.

Octav

09-13-2011, 02:17 PM   #2
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I knew that but that's some nice reading regardless. Thanks.
09-13-2011, 03:52 PM   #3
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Bokeh is also a term used to describe the mental haze when one is/has been inebriated - hmmm; I still have that single malt scotch I got when I was in scotland, who wants to get bokeh'd?
09-13-2011, 06:23 PM   #4
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Tl;dr

09-13-2011, 07:34 PM   #5
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QuoteOriginally posted by Eagle_Friends Quote
Tl;dr

I clicked the link to the article, it opened the pdf (45 pages!!) and then got an error on my Adobe reader.

"There was an error processing a page. Operation or data is too complex"

Sounds appropriate
09-14-2011, 03:51 AM   #6
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QuoteOriginally posted by steve1307 Quote
I clicked the link to the article, it opened the pdf (45 pages!!) and then got an error on my Adobe reader.
Try updating the Adobe reader, or use another web browser...
09-14-2011, 06:20 AM   #7
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QuoteOriginally posted by Digitalis Quote
Bokeh is also a term used to describe the mental haze when one is/has been inebriated - hmmm; I still have that single malt scotch I got when I was in scotland, who wants to get bokeh'd?
Sadly, you are too far away. I'll just have to stare at lens bokeh instead,
09-15-2011, 05:04 PM   #8
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interesting, reading into page 38 (i've skimmed it as its all over my head at this time of night), I wonder whether this explains the difference between the M85 and M100...maybe its just chance, but I definitely noticed the M100 is sharper and easier to focus, but that the M85 has a nicer bokeh

09-16-2011, 06:10 AM   #9
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QuoteOriginally posted by hoojammyflip Quote
interesting, reading into page 38 (i've skimmed it as its all over my head at this time of night), I wonder whether this explains the difference between the M85 and M100...maybe its just chance, but I definitely noticed the M100 is sharper and easier to focus, but that the M85 has a nicer bokeh
I think you've just described the difference between the $8 bottle of rum and the $45 bottle of rum.
09-16-2011, 09:49 AM   #10
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QuoteOriginally posted by Clinton Quote
I think you've just described the difference between the $8 bottle of rum and the $45 bottle of rum.
Please can you explain what you mean? I'd not compare either lens as a bottle of $8 rum!

I've seen some old reviews of 100mm lenses....the M100/2.8mm was sharper than the others in the test, including the M macro and Tamron 90/2.5. Its on the web, a comparison of 100mm lenses from yesteryear, made in a magazine from that time. Certainly, in my primitive home testing of the lenses, the M100 is very sharp. However, I have had some really superb bokeh out of the M85.

http://www.pbase.com/steephill/teles

I believe that the M85 was potentially under corrected for spherical aberation, Pentax described it in their marketing blurb as "creates a soft focus effect in the areas just beyond the depth of field". Marketing blurb on the Pentax manuals website.

Last edited by whojammyflip; 09-16-2011 at 10:05 AM.
09-16-2011, 10:26 AM   #11
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Which comes round to the question, what are you looking for in a lens? The M100 might have the edge in absolute sharpness, but the M85, with under corrected aberations may be betters as a portrait lens. Beauty is in the eye of the beholder, but I'd not compare either to cheap booze!!
09-16-2011, 01:17 PM   #12
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QuoteOriginally posted by octavmandru Quote
Did you know that "Bokeh" is a Japanese word?

For those interested, I found this article about the topic.
Enjoy the reading.

Octav
That is a great article, one member Rhodopsin first introduced to PF (I believe) awhile back in this thread. Interesting reading, though it does get a bit heated at times over using the term "bokeh" for OOF. Anyway, there were two portions of that article I found most informative, and also surprising. First the informative:

"A composition parameter which can help us to achieve this objective is the adjustment of the blurring in front of and behind the main subject by a suitable combination of aperture, focal length and taking distance. . . . blurring always depends on a large number of parameters. . . . All the parameters listed here influence the phenomena outside the focal plane:

Picture format
Focal length
f-number
The camera-to-subject distance
Distance to the background or the foreground
Shapes and patterns of the subject
Aperture iris shape
Aberrations of the lens
Speed of the lens
Foreground/background brightness
Colour



It might seem one might just do everything right and good bokeh is bound to follow. So I was surprised to read in the Zeiss article (page 26) that some lenses may be incapable of buttery-smooth bokeh because the aperture values "reach a kind of saturation beyond a background distance of about 10 m. Thus, the blurring does not become any greater at larger distances":

"The chart describes a typical photographic situation e.g. in portrait photography: the object field is 70cm wide and photographed in 35 mm format with an 85mm lens. The focus distance to the main subject set on the lens is therefore 1.8 metres.
The distance of the background from the main subject is indicated on the horizontal axis; the vertical axis shows the size of the circle of confusion with reference to the image diagonal. Therefore in this chart the region of the depth of field with which we have been concerned in the first part is up at the top on the left, just outside the scale; at this point the circles of confusion are diagonal/1500 or less; we are there still close to the focus; as we move to the right we move away up to a distance of 100 metres in the background.
Each curve in the chart represents one of the aperture values specified in the legend and all curves have the same character. Initially they fall uniformly (in this process the circles of confusion gradually become larger) and then reach a kind of saturation beyond a background distance of about 10 m. Thus, the blurring does not become any greater at larger distances. This limit depends, of course, on the aperture and when we compare the figures with our experience or just try it with our camera , we learn that we need circles of confusion larger than 1/100 of the diagonal in order to separate the main subject from the background."
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