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08-25-2012, 09:59 AM   #1
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FA*24 weird wide open OOF highlight

While taking night shot with my recently bought FA* 24, I noticed that it has weird shape of OOF highlight when it's wide open. It's not perfect circle but it's not hexagon either (it has 8 blades).


Here's a crop wide open (I tried both with aperture ring on A and directly F2.0 but the result is the same)



As a comparison, here's a crop taken from the same spot, with FA43 wide open


Then I got curious and want to see the highlight when stop down. The following crop are taken at a different time:

F2.0


F2.8


F3.5


Turns out the highlights are only weird when the lens is set to wide open. I wonder what is wrong with my copy and how can I address it? Or is it normal for FA *24? For such an expensive lens I'm somewhat dissapointed. First of all the sharpness wide open isn't what I expected (perfectly fine at F2.8 but then it's so large for only a F2.8 lens). The focus also not easy to lock with my K-5. And then this highlight weirdness

08-25-2012, 10:19 AM   #2
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Huh, wide open the highlights should be mostly circular. The shapes should definitely not be so irregular. You might want to send that lens in for repairs. Or use it to take photos with a spooky feeling to them.
08-25-2012, 11:41 AM   #3
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I'm suspecting the blades aren't opening all the way. If you notice you have a line of sorts above and below the bokeh in the first shot - possibly reflections of the in-the-way blade(s)?

You'll also notice you have a half-smooth effect as well. The lens could just use a little professional cleaning to get the blades to behave themselves...
08-25-2012, 03:04 PM   #4
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My FA24 has perfectly round bokeh wide open. It does show the slight increase of intensity around the fringe of bokeh circles/oblongs, and there is some texture like with the lower portion of your samples, but it doesn't have the spots in the bokeh points that your lens shows.

What I find most interesting about your samples is the "solar flare," if you will, the points of bokeh that are outside of the contiguous OOF point. I would almost expect that the aperture leafs are not only failing to open fully, but might also have become worn and shiny, causing a reflection that you see there.

That said, while it is an imperfection in the lens, it probably wouldn't affect most of the images that I capture with my FA24: the high contrast bokeh that you show here is uncommon in images and almost never a visual point of interest to non-photographers. I would much rather have problems with my aperture leafs than with lens alignment, for example.

If this problem bothers you and you can return the lens, do so. If you can't, then use the lens for a month or two and determine for yourself whether the other merits of this lens make it justifiable to get the lens fixed. This problem won't affect the high-contrast rendering of the lens, the excellent stopped-down resolution, or the fairly unique proposition of a 135-frame 24mm f/2 lens stuck between the categories of huge 24/1.4 lenses, huge f/2.8 zooms, and the slower/smaller 21/3.2.

And then, there's always the journalistic standby: if you can't fix it, feature it.

08-25-2012, 04:34 PM   #5
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You can check the lens at wide open by looking at it.
I think your copy is faulty and cannot be wide open.
08-25-2012, 05:43 PM   #6
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QuoteOriginally posted by Sagitta Quote
I'm suspecting the blades aren't opening all the way. If you notice you have a line of sorts above and below the bokeh in the first shot - possibly reflections of the in-the-way blade(s)?

You'll also notice you have a half-smooth effect as well. The lens could just use a little professional cleaning to get the blades to behave themselves...
QuoteOriginally posted by hoanpham Quote
You can check the lens at wide open by looking at it.
I think your copy is faulty and cannot be wide open.
The problem is, I can't see the blades when it's wide open. I see something circular but not the blades just the opening inside the lens.
I guess I really have to service the lens..

QuoteOriginally posted by JonPB Quote
My FA24 has perfectly round bokeh wide open. It does show the slight increase of intensity around the fringe of bokeh circles/oblongs, and there is some texture like with the lower portion of your samples, but it doesn't have the spots in the bokeh points that your lens shows.

What I find most interesting about your samples is the "solar flare," if you will, the points of bokeh that are outside of the contiguous OOF point. I would almost expect that the aperture leafs are not only failing to open fully, but might also have become worn and shiny, causing a reflection that you see there.

That said, while it is an imperfection in the lens, it probably wouldn't affect most of the images that I capture with my FA24: the high contrast bokeh that you show here is uncommon in images and almost never a visual point of interest to non-photographers. I would much rather have problems with my aperture leafs than with lens alignment, for example.

If this problem bothers you and you can return the lens, do so. If you can't, then use the lens for a month or two and determine for yourself whether the other merits of this lens make it justifiable to get the lens fixed. This problem won't affect the high-contrast rendering of the lens, the excellent stopped-down resolution, or the fairly unique proposition of a 135-frame 24mm f/2 lens stuck between the categories of huge 24/1.4 lenses, huge f/2.8 zooms, and the slower/smaller 21/3.2.
Thanks for confirming that this isn't normal.

Regarding uncommon / not a visual interest shot, I didn't plan to take the first shot. I was using Live VIew and my at one time my K-5 failed to focus and gave up at the lens MFD. And that's when I saw the highlights, they're clearly visible even without zooming.
But I intend to use my FA24 for low light / night shot and soon or later I'm bound to find some OOF highlights in the background although perhaps won't be so noticeable like this. I'd rather have octagon highlights to this irregular thing.

I'm trying hard to like this lens, because I really wanted it for very long time but only able to buy it recently (1 month ago).
08-26-2012, 04:00 AM   #7
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Its not unusual that you can't see the blades when wide open. Try stopping down and see how they look.
I don't know what exactly is wrong, but we can all agree that the bokeh highlights should not look like that.
Oh, btw, do you have a filter on it? A filter can affect highlights (though I can't imagine what kind of filter could do that)
08-26-2012, 08:25 AM   #8
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QuoteOriginally posted by sajah Quote
While taking night shot with my recently bought FA* 24, I noticed that it has weird shape of OOF highlight when it's wide open. It's not perfect circle but it's not hexagon either (it has 8 blades).
My FA*24/2 has no such bokeh at f2-3.5. Sorry for unpleasant info.

08-26-2012, 10:51 AM   #9
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QuoteOriginally posted by ogl Quote
My FA*24/2 has no such bokeh at f2-3.5. Sorry for unpleasant info.
No problem & thanks!

QuoteOriginally posted by Na Horuk Quote
Its not unusual that you can't see the blades when wide open. Try stopping down and see how they look.
I don't know what exactly is wrong, but we can all agree that the bokeh highlights should not look like that.
Oh, btw, do you have a filter on it? A filter can affect highlights (though I can't imagine what kind of filter could do that)
Yes the lens came with a Kenko Portrait Enhancer filter attached. I don't really know what a Portrait Enhancer filter is but I assure you it's not the cause of the weird highlight shape, I've tested with & without filter and came out the same.

In my original post I included crop photos of F2.8 and F3.5 highlights, they are normal for stop down highlights. I just checked the blades at F2.8 they're not perfect but close to octagon shape and if you see the highlights in the picture above they resemble the shape formed by the blades at F2.8 and 3.5 respectively.

Thanks for taking interest though!
08-26-2012, 01:01 PM   #10
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If the camera is faulty, you can shot in Manual mode, set the lens aperture at f2.0, not at A.
The lens should act like a manual lens. Set at A, the body controls the aperture pin of the lens.
08-27-2012, 04:44 AM   #11
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I did that. Both A and direct F2.0, result is the same. Furthermore, while the first two pic in my original post were taken with Pentax K-5, the last three pictures were taken with a different camera, a NEX-5 + Pentax K adapter.

So it's definitely not the camera's fault.
08-27-2012, 05:16 AM   #12
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May be you should try to get a quote from local service for adjustment?
Looks like the lens cannot fully open, more like f2.2 or f2.5.

If you can still see (by your eyes) the blades at wide open position, then it has faulty.

Normally, I won't care since half click down does give sharper compromise - I have a few one whole stop still perfect circle.
But for this lens, the octagon shape is not so nice. It can still use in other cases then.
09-17-2012, 04:59 AM   #13
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was there any resolution to this issue?
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