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03-24-2015, 11:23 PM   #1
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DA 15 / DA 20-40 starburst glare?

Hi everyone. So I'm in Metz, France, and I've noticed that when taking pictures of artificial light sources which aren't centered in the frame, there will be a blue glare radiating from the lights. Two examples are posted below.

The first, taken with a DA 15:



It happens with the DA 20-40 too, but it looks much worse due to the glare's lack of definition:



I've taken some night shots before, and all I got were clean starbursts. I'm wondering if maybe it's just this particular kind of light which puts off that blue glow. Any ideas?

03-25-2015, 12:31 AM   #2
dms
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It's flare--did you have a filter on the lens? As regards the zoom I have not used this lens or seen lot's of other people's pictures to know if this is to be expected. Seems worse than I have seen with the 15mm--but (again) not first hand experience.

Last edited by dms; 03-25-2015 at 12:36 AM.
03-25-2015, 12:36 AM   #3
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I've been noticing exactly the same problem in my shots. My initial thinking was to blame it on the somewhat cheap polarizer, but I have wondered about the angles as well. Wondered myself how to work this out. I see plenty of beautiful images with similar lightning without the halos. I wonder how people get it done right. PP work?
03-25-2015, 12:48 AM   #4
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No, no filters on either shot. On the one taken with the DA 15, you can see the geometry of the aperture blades.

03-25-2015, 01:03 AM   #5
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Both shots are excellent. Flare happens, and these lenses are among the most flare resistant lenses in their classes.
03-25-2015, 01:19 AM   #6
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No filters on my lenses either

I have the same issues with flare, and yes they do seem to be worse on the extremes. The smc DA 4/15 Limited.



Another low light shot with the smc DA15:



No flare of note above, but here's the same point of view with the Zeiss Distagon T* 2/35:



Flare is more of a problem with the Zeiss image on the edges when you compare the same scene captured using two different lenses. Somewhat annoying.

And how about the smc DA70 Limited? I really like this lens, but the flare is a bit ordinary here.



I don't have a solution other than post processing to remove it, and if it's neater like the flare from the DA15, I'm not inclined to bother doing anything with it unless I feel it's needed (I do this for a hobby and don't have time to get everything perfect).

I hope some good suggestions follow to help us both.

Last edited by Tas; 03-25-2015 at 01:20 AM. Reason: I missed a space when typing.
03-25-2015, 01:48 AM   #7
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I would say that this looks more like sensor flare (reflections that occur between the different sensor layers) than lens flare. Lens flare usually produces secondary images of the diaphragm blades that are running towards the center of the frame, while sensor flare artifacts are rounded blobs or dots that are running away from the center of the frame.

Sensor flare affects many cameras equipped with Sony sensors, see for example this thread about the Sony A7 full-frame mirrorless camera:

A7 unacceptable flare in night shots ?: Sony Alpha/NEX E-mount Talk Forum: Digital Photography Review

Cheers!

Abbazz

Last edited by Abbazz; 03-25-2015 at 01:53 AM.
03-25-2015, 02:15 AM   #8
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Yeah, I've already seen some sensor flare on my A7 - I read speculation that it's the baked-in phase detection AF sensors in the stack i.e. not present in the A7R.

No problem same shot on my K-S1.

03-25-2015, 05:12 AM   #9
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Those lights are very overexposed, so flare is more likely to show up. If you expose so that the lights are not blown out, the flare will probably be so faint it won't be noticed. But the rest of the frame will be much darker as well..
Modern lens coatings: these eliminate a lot of flare and ghosting, but when they fail, the failure will look more unnatural than it would with older lenses that have simpler optics and coatings
Modern lights: many modern lights are complicated. They don't radiate a whole spectrum of light wavelengths, they might flash at an odd rate, they might have hidden secondary colours, they might have reflectors built in.. so there is a bigger chance it will behave in a way that you wouldn't expect it to.
The best you can do is pick a WB where the flare is not too noticeable or just clone it out. You can try experimenting with different angles, but with raw photos, darkening the flare is usually easiest.

Edit: Also, really nice photos in this thread
03-25-2015, 05:15 AM   #10
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The starbursts happen when you don't have rounded aperture blades. the DA15 and DA21 are known as among the best for this.

The 20-40 has rounded aperture blades. It means the bokeh will be smoother but the star effect will be worse. That's why I haven't replaced my DA21 with the 20-40.

The HD 15 and 2 also have rounded blades.
03-25-2015, 06:28 AM   #11
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Do not go too far down the path of sensor reflections. I have had lenses where sensor reflections were an issue, combined with In my case bright parts in the optical path at the rear of the lens. These do NOT result in geometric reproductions of the aperture, but in patterns of high and low contrast (I.e. Cloudy) areas of the frame.

Reflections and flare of the aperture shape are always a problem with lenses when there is an extremely bright light in the field of view.

I suspect the lens not the sensor, and it is unavoidable
03-25-2015, 07:33 AM   #12
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QuoteOriginally posted by Lowell Goudge Quote
I suspect the lens not the sensor, and it is unavoidable
Nobody needs to suspect anything. flare, diffraction and other comparable phenomenons are pretty well understood and documented. In optics books and such...

Look at the reviews of the HD limiteds and the 20-40, there are loads of comparisons there.
03-25-2015, 10:36 AM   #13
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QuoteOriginally posted by bdery Quote
Nobody needs to suspect anything. flare, diffraction and other comparable phenomenons are pretty well understood and documented. In optics books and such...

Look at the reviews of the HD limiteds and the 20-40, there are loads of comparisons there.
I don't disagree, just was trying to be a little softer to someone who has paid probably a lot for the lens and is a little disappointed.

Although I have never tried, I suspect you could, with the flare pattern map out the lens groupings, Something to play with on some older lenses with poorer coatings. Maybe my super tak 50/1.4 with 8 elements. Surely the flare would be different than my K50/1.4 which is 7 elements.
03-25-2015, 11:03 AM   #14
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QuoteOriginally posted by Lowell Goudge Quote
Although I have never tried, I suspect you could, with the flare pattern map out the lens groupings, Something to play with on some older lenses with poorer coatings. Maybe my super tak 50/1.4 with 8 elements. Surely the flare would be different than my K50/1.4 which is 7 elements.
It's much more strongly linked to the coatings than the lens elements. I wrote a short article about this

All About SLR Lens Coatings - Articles and Tips | PentaxForums.com
03-25-2015, 02:31 PM   #15
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QuoteOriginally posted by bdery Quote
It's much more strongly linked to the coatings than the lens elements. I wrote a short article about this

All About SLR Lens Coatings - Articles and Tips | PentaxForums.com
Yes I know the flare is internal reflections off the element surfaces, hence the emphasis in coatings, what I was referring to is that for each reflection of the apeture in the flare pattern, this represents the position of a boundary, or lens surface that is reflecting, the space between the aperture reflections, and relative size likely relate to the position of the surfaces that are reflecting, hence you could use them to deduce the optical design, or confirm which elements in the design were causing the reflections
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