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12-11-2010, 12:41 AM   #1
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Octagonal Bokeh

Dear All,

I accidentally found this bokeh while taking a blurry picture of the Xmas tree with my A 50 1.4 lens.

Is this normal? which one is better the circular, hexagonal or this one?

Thanks


Last edited by HoBykoYan; 10-09-2012 at 02:13 AM.
12-11-2010, 12:46 AM   #2
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QuoteOriginally posted by HoBykoYan Quote
Dear All,

I accidentally found this bokeh while taking a blurry picture of the Xmas tree with my A 50 1.4 lens.

Is this normal? which one is better the circular, hexagonal or this one?

Thanks
It's normal have non-circular boked when you stop down the lens (i.e. not wide open)

However, some lenses have more aperture blades (14+) will also give you circular boked when stopped down. Which boked is better is rather a personal preference IMHO.
12-11-2010, 01:14 AM   #3
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bokeh is all about smoothness, so the circular ones are better.
12-11-2010, 02:30 AM   #4
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It's normal for lenses with non circular aperture blades. If you don't want to chase lenses with many blades then have a look at DA*55 and DFA100WR, they have rounded aperture blades so even stopped down they produce circular highlights

12-11-2010, 02:54 AM   #5
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QuoteOriginally posted by Eagle_Friends Quote
bokeh is all about smoothness, so the circular ones are better.
I beg to differ. (not my pic btw)

12-11-2010, 03:13 AM   #6
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Better is the one that doesn't have well defined edge.

So that when you have a busy background, separate features blend together instead of drawing distinct shapes.

Now i'm just not sure if there was such thing, or the smoothness of OOF spot edge depends on the light source.

If you took the image @ F/1.4 they would be round.
12-11-2010, 07:35 AM - 1 Like   #7
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I beg to differ with every one here.

While the shape of the bokeh on point lights represents the shape of your aperture, and to some extent the number of blades, what is "best" is a function of what you are trying to achieve.

If you want round OFF highlights at intermediate apertures, then you need to look at getting a lens with a high number of aperture blades which are shaped to yeild perfect or nearly perfect circles, (or just shoot wide open) These usually are old Preset lenses, because once automatic apertures came about, the need for fast acting apertures required reduced number of blades, due to the drag ont he blades and the speed at which they had to work.

The preset lenses also have the blades in a different optical position, and that modifies the Bokeh as well.

I di a comparison between a preset 135mm and an SMC tak 135mm, and at correspondingly similar apertures, the preset seemed to have more separation of background and foreground (out of focus vs in focus) Check out the 135mm lens club for the comparisons.

Now, take the same lenses out at night, and stop them down, with a newer lens that has 6 or 8 blades, you will get a starburst on streetlights with 6 or 8 spokes, which is caused by defraction at the corners of the blades, you don't see that with a round aperture, but you might want it. Note the actual number of spokes is blades *2 but since opposite lines overlap on even numbers of blades yo don;t see them. Lots of Nikons however use 9 blades which yeild 18 spokes.

So, the shape of the aperture is good and bad depending on what you want. There is no right or wrong, just different
12-11-2010, 11:03 AM   #8
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Here is an example showing a couple of features Lowell mentioned. The lens has 7 blades so 14 spokes.



12-11-2010, 11:07 AM   #9
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QuoteOriginally posted by Lowell Goudge Quote
There is no right or wrong, just different
Wise words. This is supposed to be art, after all. Which is one of the reasons why bokeh preference is a hard thing to agree on.

If you know what you want, and what your lens is capable of, you can use any "shape" of bokeh to good effect, IMHO. You run into problems when you do not plan with your gear in mind.
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