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08-24-2011, 04:45 AM   #1
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K50/f1.2 at f2-2.8

Hi everyone, I'm looking at buying a K50/f1.2 and had a quick question about OOF rendering.

How does the K render our-of-focus highlights stopped down around f2-2.8?

The reason I ask is that I currently use the M50/f1.4, and while it renders gorgeous circular highlights at f1.4, it produces odd 'corners' at f2-2.8 - I'm assuming that these are the result of aperture blades not quite overlapping...

I know the K doesn't have rounded blades, but does it produce the affect I'm experiencing on the M?

Here's an example of what I mean...



08-24-2011, 05:32 AM   #2
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QuoteOriginally posted by nickthetasmaniac Quote
Hi everyone, I'm looking at buying a K50/f1.2 and had a quick question about OOF rendering.

How does the K render our-of-focus highlights stopped down around f2-2.8?

The reason I ask is that I currently use the M50/f1.4, and while it renders gorgeous circular highlights at f1.4, it produces odd 'corners' at f2-2.8 - I'm assuming that these are the result of aperture blades not quite overlapping...

I know the K doesn't have rounded blades, but does it produce the affect I'm experiencing on the M?

Here's an example of what I mean...
No, the K series will do the same things. It does not have rounded blades. Check out the sigma 50mm f/1.4 with 9 rounded aperture blades
08-24-2011, 05:46 AM   #3
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Yeah the K version only has 8 blades so the OOF highlights will get quite ugly once stopping down.
The A series on the other hand has 9 blades and will be more circular stopped down.
08-24-2011, 07:19 AM   #4
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The K50/1.2 at f2.8 won't look much different from the shot you posted. But then my FA43ltd looked just the same. I have to say though, I prefer 8 bladed OOF to 9 bladed. The only lens in that range that would look better is DA*55. thanks to it's rounded blades, the OOF highlights stay circular to nearly f4....

anyway, here are few pics to help you decide:
K50/1.2 @ f4 if I remember correctly:


FA43 @ f2.8


DA*55 @ f2.8


DA*55 @ f2.2



Last edited by axl; 08-24-2011 at 07:32 AM.
08-24-2011, 07:26 AM   #5
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QuoteOriginally posted by nickthetasmaniac Quote
I know the K doesn't have rounded blades, but does it produce the affect I'm experiencing on the M
As I said in the OP, I know that the K doesn't have rounded blades.

I think people have misunderstood - I don't mean the octagonal bokeh (or whatever it's called with 8 sides) - I'm fully aware that that is what you get with straight edged blades.

I'm referring to the 'corners' of the octagons, which display a tail of sorts at f2-2.8 (which is visible in the pic I posted...). If you look inside an M50/f1.4 stopped down to these apertures, you can see that the tip of each aperture blade pulls slightly back from the preceding blade. By roughly f4 they overlap properly and the highlights are standard octagons...

Sorry, I don't know how else to explain it...
08-24-2011, 07:31 AM   #6
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the "ninja stars" are very common and may vary from copy to copy. I don't remember my K50/1.2 creating ninja stars but my FA43 and K55/1.8 did suffer from this "effect"...
08-24-2011, 07:37 AM   #7
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Here are a couple A50/1.2 shot just for reference. Sometimes the same little "notches" that you describe show up (even with the 9 blades). Anyways, I don't think it really matters...hard outer bokeh rings are much more distracting. And it really depends on how strong the specular highlights are in your scene.

at F1.8



And a couple recent ones at F2...



08-24-2011, 07:37 AM   #8
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QuoteOriginally posted by axl Quote
the "ninja stars" are very common and may vary from copy to copy. I don't remember my K50/1.2 creating ninja stars but my FA43 and K55/1.8 did suffer from this "effect"...
Ok thanks

**edit** Thanks Jim as well, posted as I replied!

08-24-2011, 02:51 PM   #9
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My copy of K50f1.2 does have a little sharp ninja edges at one click down, but not significant.
At 'half click' down, it looks better, more rounded shape.
And same at two clicks down.
Only the first click does have sharp stars shape, but as I mentioned, not significant.
08-24-2011, 05:11 PM   #10
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QuoteOriginally posted by hoanpham Quote
My copy of K50f1.2 does have a little sharp ninja edges at one click down, but not significant.
At 'half click' down, it looks better, more rounded shape.
And same at two clicks down.
Only the first click does have sharp stars shape, but as I mentioned, not significant.
Thanks - that sounds similar to the M50, just slightly milder
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