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Frequent Contributor
Posts: 28
Registered: ‎09-17-2016

Octagonal Bokeh Question

Croppedbokeh.JPGHi, I'm curious about something I noticed today in one of my photosCroppedbokeh.JPG. Here's a bit of background info: The attached photos (one is cropped to show a close up of bokeh) were taken with a Canon 100mmL lens (Rebel T3i camera). The settings for the water droplet are f/8, 1/200, ISO 200 and for the sunflowers: f/8, 1/320, ISO 400. If you take a look at the top left in the close up photo of the water droplet, the bokeh looks octagonal shaped. Yet, the bokeh looks circular in the sunflower photo.  This is the first time I've seen the octagon shape. If bokeh is, among other things, the shape of the lens aperture, why would it appear round in one photo and octagonal in another using the same lens and similar settings? 

Sunshine.JPG

VIP
Posts: 11,351
Registered: ‎12-07-2012

Re: Octagonal Bokeh Question

"...bokeh is, among other things, the shape of the lens aperture, ..."

 

You are forgetting the "other" things.  Bokeh is effected by the size of the aperture, by the number of aperture blades along with the shape of the blades.  Besides that, the distance from the light source and the DOF in the shot will effect bokeh.  Even the type light, diffused or pinpoint will change it.

EOS 1DX and 1D Mk IV and several lenses!
Reputable Contributor
Posts: 577
Registered: ‎01-25-2018

Re: Octagonal Bokeh Question

B&H has a pretty decent basic explanation of bokeh with a link to more information.  Google B&H bokeh.

 

Under some conditions you can also get light reflection from inside the lens assembly with high brightenss off angle points of light in images which projects back onto the subject and further complicates matters.

 

Rodger

EOS 1DX M2, 1DX, 1D M2, EOS 650 (film), many lenses, XF400 video
Respected Contributor
Posts: 1,861
Registered: ‎12-02-2012

Re: Octagonal Bokeh Question

[ Edited ]

Any lens will give round bokeh shooting wide open.  When you stop down you start to see the shape of your aperture blades.  The blades will form a more round shape if they are rounded rather than just straight.  It also helps with roundness if there are more blades rather than fewer.  

 

You can even make funny shapes by putting a black card over the lens with a shape cut into it.  Stars, triangles, airplanes, kitties, whatever you like. Look at Bokeh Masters.

Scott

Canon 5d mk 4, Canon 6D, EF 70-200mm L f/2.8 IS mk2; EF 16-35 f/2.8 L mk. III; Sigma 35mm f/1.4 "Art" EF 100mm f/2.8L Macro; EF 85mm f/1.8; EF 1.4x extender mk. 3; EF 24-105 f/4 L; EF-S 17-55mm f/2.8 IS; 3x Phottix Mitros+ speedlites

Why do so many people say "FER-tographer"? Do they take "fertographs"?
Frequent Contributor
Posts: 28
Registered: ‎09-17-2016

Re: Octagonal Bokeh Question

Thank you very much, Scotty for the info and Someone else mentioned cutting out shapes out of construction paper To get different shaped bokeh.. I am definitely going to do that!
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VIP
Posts: 11,351
Registered: ‎12-07-2012

Re: Octagonal Bokeh Question

 
EOS 1DX and 1D Mk IV and several lenses!
VIP
Posts: 11,351
Registered: ‎12-07-2012

Re: Octagonal Bokeh Question

All lenses are not created equal. Even no aperture blades dose not guarantee perfect bokeh
EOS 1DX and 1D Mk IV and several lenses!
Honored Contributor
Posts: 5,009
Registered: ‎06-25-2014

Re: Octagonal Bokeh Question


@ebiggs1 wrote:
All lenses are not created equal. Even no aperture blades dose not guarantee perfect bokeh

Moreover, there's no unanimous agreement as to what constitutes perfect bokeh. Among those with strong opinions on the subject, arguments erupt from time to time.

Bob
Philadelphia, Pennsylvania USA
VIP
Posts: 11,351
Registered: ‎12-07-2012

Re: Octagonal Bokeh Question

"...there's no unanimous agreement as to what constitutes perfect bokeh."

 

Amen!  Smiley Frustrated

EOS 1DX and 1D Mk IV and several lenses!
Frequent Contributor
Posts: 28
Registered: ‎09-17-2016

Re: Octagonal Bokeh Question

Why do so many people say "FER-tographer"?......
I think perhaps because they're from Brooklyn!
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