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07-07-2017, 08:14 AM   #1
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Aperture shapes.

So... I've noticed that 5, 6, 8, and 9 blade apertures are really common.

These lead to common aperture shapes of:
  • Pentagons
  • Hexagons
  • Octagons
  • Nonagons
But, I'm more interested in less common polygon shapes.

Triangle:
Square:Diamond: (2 blades):
  • Olympus XA
Pentagon: (Really common)
Hexagon: (Really common)
Star (Hexagon variant):
Septagon/Heptagon (7 sides):
Octagon: (Really common)
Nonagon (9 sides): (Really common)
Decagon (10 sides):
Hendecagon (11 sides):
Dodecagon (12 sides):
Triskaidecagon (13 sides):

Icosagon (20 sides):


So, what are some uncommon iris shapes you've seen, or know about?


Last edited by timw4mail; 07-07-2017 at 09:48 AM. Reason: Updating list
07-07-2017, 08:36 AM - 1 Like   #2
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The m42 (or m39) industar 61 has a really nice star pattern closed down between f4 and f11. It has a 6 bladed aperture, rounded but opposite to the regular rounded aperture. Im sure you cand find some nice pics on the internet.

I also think the volna is similar but not so sure

edit: industar 61 l/z and volna 9
07-07-2017, 08:51 AM - 1 Like   #3
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A lot of point-and-shoot cameras have only two aperture blades. Some use notched blades (creating square bokeh) and some use curved blades (creating cateye/elliptical bokeh).

Some instant film and point-and-shoot cameras have a rotating disk or slider with different-sized aperture holes (creating circular bokeh).

There's also a number of kickstarter and novelty lenses that offer waterhouse stop apertures with unusual shapes (stars, snowflakes, speckle, hearts).
07-07-2017, 08:53 AM   #4
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QuoteOriginally posted by photoptimist Quote
A lot of point-and-shoot cameras have only two aperture blades. Some use notched blades (creating square bokeh) and some use curved blades (creating cateye/elliptical bokeh).

Some instant film and point-and-shoot cameras have a rotating disk or slider with different-sized aperture holes (creating circular bokeh).

There's also a number of kickstarter and novelty lenses that offer waterhouse stop apertures with unusual shapes (stars, snowflakes, speckle, hearts).
I was leaning more toward diapharms in unaltered form, and not fixed cutouts
Examples are better than generalizations

07-07-2017, 08:59 AM   #5
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You can quickly google any blade count to find others:

For example "13 blade" aperture - Google Search reveals the Helios 44 and Focal 200mm f4.5 telephoto have that count.

A search for "14 blades" gets the Carl Zeiss Jena Tessar 2.8/50 and others.
07-07-2017, 09:16 AM - 1 Like   #6
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QuoteOriginally posted by timw4mail Quote
I was leaning more toward diapharms in unaltered form, and not fixed cutouts
Examples are better than generalizations
Olympus XA has a two-bladed manual aperture (f/2.8-f/22). The shape is diamond.


Steve
07-07-2017, 09:22 AM - 1 Like   #7
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Jupiter-9 (various factories, various mounts): 15 curved blades, round opening at all apertures.

Arsenal Jupiter-8M (Contax/Kiev): 9 blades, scalloped pattern



Steve

Last edited by stevebrot; 07-07-2017 at 10:26 AM.
07-07-2017, 09:55 AM   #8
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QuoteOriginally posted by stevebrot Quote
Olympus XA has a two-bladed manual aperture (f/2.8-f/22). The shape is diamond.


Steve
QuoteOriginally posted by stevebrot Quote
Jupiter-9 (various factories, various mounts): 15 curved blades, round opening at all apertures.

Arsenal Jupiter-8 (Contax/Kiev): 9 blades, scalloped pattern



Steve
Do you have some links about these lenses?

07-07-2017, 10:00 AM   #9
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But its not that simple. The Pentax M 50mm f1.7 has 6 blades, but the way its aperture stops down its not a perfect hexagon at all apertures. The older Sigma 30mm produces triangular highlight bokeh (due to coma?). Many modern lenses have rounded blades, which keeps the shape more round and avoids hexagons or whatever. This also seems to ruin the 'starburst' effect. Lots of people complained when the SMC DA limited lenses were updated to HD DA limited with rounded blades. Apparently this changes the bokeh and starbursts/diffraction spikes. You can check online for examples, particularly with the DA 21mm.

Anyway, if you want custom bokeh, here are some options
a) some lenses are designed to use aperture blades, like the Daguerrotype
b) some lenses can be modified. There are tutorials and even ebay stores that sell Helios 44 modification that makes the bokeh square. You can get the modified Helios from ebay at a reasonable price
c) You can take a piece of black plastic, cut the shape of aperture that you wish (heart, unicorn, whatever) and put it on the front of the lens' filter. There are threads and many blog posts, youtube videos about this simple DIY
07-07-2017, 10:11 AM   #10
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QuoteOriginally posted by Na Horuk Quote
The Pentax M 50mm f1.7 has 6 blades, but the way its aperture stops down its not a perfect hexagon at all apertures.
It depends on copy (mine doesn't do that), though your point is well-made. Rare is the lens with less than nine blades that is symmetrical at all apertures.


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07-07-2017, 10:24 AM   #11
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QuoteOriginally posted by timw4mail Quote
Do you have some links about these lenses?
Are you asking for bokeh and highlight examples? Google is our friend as is Flickr. Aside from bokeh examples with the J-9, I don't have any to offer:

Jupiter-9 bokeh: Beads on Vibrant Leaves | The peony plant near my front porc? | Flickr

For photos of the lenses and technical details, the J-9 reviews on this site have complete information, and for the other two, Google is still our friend.

Steve

Last edited by stevebrot; 07-07-2017 at 10:31 AM.
07-07-2017, 10:44 AM   #12
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Lens with most aperture blades? lists a few dozen unusual blade-count lenses.
07-07-2017, 10:44 AM   #13
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QuoteOriginally posted by Na Horuk Quote
But its not that simple. The Pentax M 50mm f1.7 has 6 blades, but the way its aperture stops down its not a perfect hexagon at all apertures. The older Sigma 30mm produces triangular highlight bokeh (due to coma?). Many modern lenses have rounded blades, which keeps the shape more round and avoids hexagons or whatever. This also seems to ruin the 'starburst' effect. Lots of people complained when the SMC DA limited lenses were updated to HD DA limited with rounded blades. Apparently this changes the bokeh and starbursts/diffraction spikes. You can check online for examples, particularly with the DA 21mm.

Anyway, if you want custom bokeh, here are some options
a) some lenses are designed to use aperture blades, like the Daguerrotype
b) some lenses can be modified. There are tutorials and even ebay stores that sell Helios 44 modification that makes the bokeh square. You can get the modified Helios from ebay at a reasonable price
c) You can take a piece of black plastic, cut the shape of aperture that you wish (heart, unicorn, whatever) and put it on the front of the lens' filter. There are threads and many blog posts, youtube videos about this simple DIY
Okay, the shape for the majority of the aperture range. A lot of lenses have odd aperture shapes for the first few stops. My point with aperture shapes is more the (stock) shape the diaphragm inside the lens makes, moreso than the bokeh, although the two are obviously closely related.
07-07-2017, 02:53 PM   #14
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There are plastic cameras that have a sort of elongated trapezoidal aperture, as changing the aperture moves the position of a widening groove in front of the lens. I don't have any of these cameras at hand right now, and I can't find an example online.
07-07-2017, 03:44 PM   #15
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then you get into the shape of the aperture at different stops - I love the look of my K55/2 at f2.8:

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