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10-30-2009, 01:09 PM   #1
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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?


Last edited by dosdan; 10-30-2009 at 01:17 PM.
10-30-2009, 01:33 PM   #2
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Taken with a Sigma 17-70mm F2.8-4.5 DC, 7 blade diaphram. Looks like 14 star points.
10-30-2009, 01:50 PM   #3
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Hadn't considered the phenomenon until you mentioned it.
One with the 16-50 - 9 blades, so indeed 18 pointed stars...

10-30-2009, 01:52 PM   #4
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Very cool, I always wondered about that!

10-30-2009, 02:02 PM   #5
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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
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Moved to Lens forum.

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