View Full Version : Canon 50mm 1.4 hexagonal bokeh

17-02-2011, 1:19pm
I've noticed when shooting at a big aperture with my 50mm 1.4, the bokeh comes out hexagonal...is this normal???

Here is an example


17-02-2011, 1:29pm
Emma the bokeh is related to the shape of the aperture. When the aperture is wide open it is closest to round but as the aperture is made smaller (larger f number) the blades that form the opening make a more hexagonal shape - it depends on the number of blades in your shutter as to what exact shape you will get. The more shutter blades, the rounder the aperture.

17-02-2011, 1:40pm
Thanks for your answer! Makes sense :)

17-02-2011, 1:55pm
I think it is octagonal rather hexagonal. It means that a 50mm 1.4f lens has 8 blades :)

17-02-2011, 2:11pm
They're fairly easy to count. Just set camera to Av and aperture to about f8, remove lens cap, look into front of lens and press the DOF Preview button. You will see the aperture close down and you will be able to count the number of blades - or it may be easier to count the number of sides to the opening. If you can't see it at f8, try a different f number.

17-02-2011, 2:39pm
The Canon 50mm F1.4 has 8 blades and the F1.8 has 5 blades. Quite easy to see in teh bokeh. The question is do you like it! :rolleyes:

17-02-2011, 2:39pm
I know that all the Canon DO leneses have hexagonal bokeh, but didn't realise that their normal lenses cando this too.
I've never experienced this with any of my Canon or sigma lenses.
Mind you, I don't have a 50mm F1.4, but my nift fifty seems to have nicer bokeh than this.

17-02-2011, 3:36pm
I didnt have a problem with it until someone mentioned it to me and now its all I see :/

17-02-2011, 6:33pm
The sigma 50mm 1.4 has 9 blades. Also some lenses have curved blades.

17-02-2011, 9:30pm
f/3.5 is not normally considered to be a 'big aperture' when the lens in question is an f/1.4 type.

Big apertures, I suppose values up to about f/2.8 would be considered big, beyond that you'll get middle sized and then at about f/5.6 and smaller would be considered small(as the lens most likely stops down to f/16).

you'll see these aperture shaped bokeh circles in your images, dependent on the focus distance and the respective distances of the elements in the scene.
so: if you focus on a subject nearer to the camera, the blur circles will be less defined and larger in the background. Also, if you focused at the same distance that you had as in this image and the elements in the frame that produced the octagonal highlights were closer than they were in this scene, they'd also look larger and less defined too. (not as much as if focusing closer tho, as focused distance plays a larger role in the rendering quality of bokeh.

Is it normal?.. yep!

FWIW, at large apertures, that is f/2 and larger, you most likely won't see the aperture blades forming any shapes like this. They're likely to be more rounded, and usually with more colour fringing too.

17-02-2011, 9:41pm
There is a comparison between the Sigma and the Canon here (http://www.youtube.com/watch?v=6uaOC-q6nP8&feature=relmfu)