Rings within bokeh lights??

[RollsUp]

Sorry about the title, I don't know the exact words to describe it.
I'm wondering if this is normal shooting at F2.8 ISO 1600 1/10 with a Tamron 28-75 @75mm on a K20D. It's the circles within the red light bokeh I'm referring to. And why is there little spots in there too?

[Marc Sabatella]

JPEG compression artifacts?

[alohadave]

It has to do with how that particular lens renders bokeh. It's going to vary based on how far away the background is and which aperture you are at.

[mattdm]

Since they can be so attention-getting, rings like that are often considered to be a factor in "bad bokeh".

[IsaacEastgate]

I find this in the bokeh on my pentax-m 50mm 1.4. I think it is related in some way to the surfaces of the lens elements, but i cant work out how. Generally, your bokeh doesn't look too bad.

[creampuff]

The rings in the out of focus circles are characteristic of lenses that have aspherical lens elements. The aspheric lens element has subtle changes of the lens curvature where the edges are flatter to correct spherical aberration.

[soccerjoe5]

I like it

[ivoire]

Agree with creampuff and alohadave. i ran into this once in a while with the sigma 10-20mm and used photoshop to smudge or blur the 'artifacts'.

[heliphoto]

My DA* 16-50 does this. I assumed the rings were an interference pattern of some sort.

Here's an example (also xmas lights)...

50mm, f/4, lens near close focus limit and lights about six feet away...

[kerrowdown]

If you don't like 'em or can't live with them, it's time to get Photoshopping.

[creampuff]

I tend to feel primes typically show better bokeh rings because they don't have that many elements when compared to zooms.

[yeedub]

My DA* 16-50mm does that too. I can see rings inside my bokeh circles. At first I thought it might be a defect too

[borno]

Here's some good reading from an old thread by carpents, I think creampuff's right about the aspherical elements

Bokeh, Specular Highlights, Guess The Lens - A Surprising Result

[rfortson]

Originally Posted by Marc Sabatella

JPEG compression artifacts?

I agree with Marc. Looks like a compression artifact to me.

I'll have to go back and look at some of my shots and see if I've gotten this before.

[RollsUp]

Thanks everybody. I'll take it that it as it being the normal characteristics for this lens since it shows up in the RAW file also.
Thanks for the link borno. I haven't read through it yet, I will go back and read it when I have more time.