Star points on lights in night shots

dosdan · 10-30-2009, 01:09 PM

The star-effect depends on the number of leaves/blades that form the lens aperture circle. With an even number of leaves, its the same name of star points as the number of leaves. While an odd number of leaves doubles the number of points.

Taken with a Pentax-DA 16-45/F4 - 8 leaves - 8 points

Taken with a Pentax-M 50/F1.7 - 6 leaves - 6 points

Can someone show an image taken with an odd number of leaves?

Dan.

Last edited by dosdan; 10-30-2009 at 01:17 PM.

junyo · 10-30-2009, 01:33 PM

Taken with a Sigma 17-70mm F2.8-4.5 DC, 7 blade diaphram. Looks like 14 star points.

**Ash** · 10-30-2009, 01:50 PM

Hadn't considered the phenomenon until you mentioned it.
One with the 16-50 - 9 blades, so indeed 18 pointed stars...

[IMG]

[/IMG]

Eruditass · 10-30-2009, 01:52 PM

Very cool, I always wondered about that!

**Lowell Goudge** · 10-30-2009, 02:02 PM

actually you always get 2 points per blade, or more appropriately a line.

the reason it looks like double the points on an odd number of blades is because the lines don't fall symetrically on top of each other.

look for a lens where the aperture does not close down symmetrically with an even number of blades and I'll bet you can see the double lines again

Damn Brit · 10-30-2009, 02:03 PM

Moved to Lens forum.

10-30-2009, 01:09 PM	#1
dosdan Pentaxian Join Date: Dec 2007 Location: Brisbane, Australia Photos: Gallery \| Albums Posts: 1,741	Star points on lights in night shots The star-effect depends on the number of leaves/blades that form the lens aperture circle. With an even number of leaves, its the same name of star points as the number of leaves. While an odd number of leaves doubles the number of points. Taken with a Pentax-DA 16-45/F4 - 8 leaves - 8 points Taken with a Pentax-M 50/F1.7 - 6 leaves - 6 points Can someone show an image taken with an odd number of leaves? Dan. Last edited by dosdan; 10-30-2009 at 01:17 PM.

10-30-2009, 01:50 PM	#3
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	Hadn't considered the phenomenon until you mentioned it. One with the 16-50 - 9 blades, so indeed 18 pointed stars... [IMG][/IMG]

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10-30-2009, 01:33 PM	#2
junyo Veteran Member Join Date: Oct 2007 Photos: Gallery Posts: 418	Taken with a Sigma 17-70mm F2.8-4.5 DC, 7 blade diaphram. Looks like 14 star points.

10-30-2009, 01:52 PM	#4
Eruditass Veteran Member Join Date: Jul 2009 Photos: Gallery Posts: 2,207	Very cool, I always wondered about that!

10-30-2009, 02:02 PM	#5
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,887	actually you always get 2 points per blade, or more appropriately a line. the reason it looks like double the points on an odd number of blades is because the lines don't fall symetrically on top of each other. look for a lens where the aperture does not close down symmetrically with an even number of blades and I'll bet you can see the double lines again

10-30-2009, 02:03 PM	#6
Damn Brit Guest	Moved to Lens forum.