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04-26-2011, 11:51 AM   #1
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Light fringing

Hello

I've been searching around to find an answer to what I think is fringing. But I have uploaded a picture of it. Hoping someone here can tell me what it is and how I can combat it.
It's the glow going from the neck (right side), running down the shoulder and arm of the girl in the picture. It's kinda annoying, anyone know how to get rid of it?

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04-26-2011, 12:00 PM   #2
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Well, I'd try stopping the lens down. The EXIF shows f 3.2 which must be wide open. You'll get sharper results higher up. I'm learning how the K5 lets me shoot much higher on the f scale, myself. Try shooting in Av and rolling up the f values. I've been shooting around f8.0 most of the time in sunlight and going up from there.

I don't think it's fringing, I think it's overexposed on the subject (but I'm novice compared with the wizened experts here).
04-26-2011, 12:12 PM   #3
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Couple of questions...

What lens was this taken with?
Were you intended to blow-out the highlights?

And lots of people want to capture highlights as blow-outs and there's nothing wrong with that. And I believe there is a time and place for everything also. However, if you weren't planning on capturing blow-outs, then a quick solution, might be to expose for the highlights.

In the event that your metering doesn't address the highlights, you could use spot metering to selectively target the highlight area and use Exposure Lock when taking the shot. Then... you can process(in RAW) to balance the scene without a controlled highlight.

Another way(perhaps simpler) might be to move the AF confirm bracket to the highlight area within the scene. Using spot this will force metering to expose for the highlight.

And perhaps as a last alternative, you could simply review your shots as adjust them on the fly by manually controlling your shutter and/or settings(ISO/aperture etc).

This is all assuming(of course) that you were not intended to blow the highlights. And so, if you were... then I'd say you'll likely have to find better glass. However, from personal experience, most lenses I know of will bloom to some degree or another when dealing with blow-outs.
04-26-2011, 12:17 PM   #4
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I am also pretty certain that it is neither the camera, nor the lens that is the real culprit here, but rather your settings: You have shot in Av-mode and set the f-ratio at 3.2; your camera responds with a exposure time of 1/3200 - which is absolutely unneccessary in a scene like this. With a handheld 200mm lens and shake reduction on, you need no more than 1/200 sec (or even less) in a situation like this.

By the way, which lens did you actually use?

B.R. / Steen G. B.

04-26-2011, 12:39 PM   #5
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Thanks for your replies I'm still a novice, so there are some things that stumble me now and then.
The lens I used was the Sigma 70-200 mm APO EX DG 2,8 Macro on the Pentax K5 body.

I didn't intend to blow out the highlights. turn the AV down, my pictures just seem to get rather dark tho...
04-26-2011, 01:11 PM   #6
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QuoteOriginally posted by mikknu Quote
Thanks for your replies I'm still a novice, so there are some things that stumble me now and then.
The lens I used was the Sigma 70-200 mm APO EX DG 2,8 Macro on the Pentax K5 body.

I didn't intend to blow out the highlights. turn the AV down, my pictures just seem to get rather dark tho...
Note that if you shoot raw it gives you the possibility of recovering blown highlights and post processing will also permit you to adjust area's that are too dark
(unavoidable fringing can also be reduced/eliminated).
04-26-2011, 02:54 PM   #7
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QuoteOriginally posted by mikknu Quote
Thanks for your replies I'm still a novice, so there are some things that stumble me now and then.
The lens I used was the Sigma 70-200 mm APO EX DG 2,8 Macro on the Pentax K5 body.
Your lens is supposed to minimize that sort of thing. That's why it has APO in its name. But the wider apertures let in more light rays, and more at an angle which is difficult to correct fully.

QuoteQuote:
I didn't intend to blow out the highlights. turn the AV down, my pictures just seem to get rather dark tho...
You could get the same exposure at f5.6 and 1/500 (I think) and end up with a similar brightness. You'd probably end up with some fringing still, but less.

If you can find a statue with similar light on it, that is, sunlight from the side and shaded on the other side, you might experiment in Av mode. That would let the exposure stay fixed and just the aperture vary.

I looked up apochromatic lenses and found that the first design was in 1763. I like this quote from Wikipedia:

"Theoretical considerations of the feasibility of correcting chromatic aberration were debated in the 18th century following Newton's statement that such a correction was impossible."
04-26-2011, 06:39 PM   #8
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The only way to stop blown highlights is to either underexpose to Preserve them or add some front lighting, either with flash or reflector

04-27-2011, 03:36 AM   #9
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QuoteOriginally posted by Just1MoreDave Quote
Your lens is supposed to minimize that sort of thing. That's why it has APO in its name. But the wider apertures let in more light rays, and more at an angle which is difficult to correct fully.

You could get the same exposure at f5.6 and 1/500 (I think) and end up with a similar brightness. You'd probably end up with some fringing still, but less.
Kinda glad to to hear you say it, I was beginning to wonder if the APO part was actually working. This lens does seem to create fringing more than my two pentax kit zoom lenses and my sigma 105 mm macro. That being said, the kit lenses can't go below f/4 or f/6,3 when zoomed in, so that can explain why they don't do it as much, due to higher f/stop. The 105 mm is a prime, so I reacon that's "it's" reason for not fringing much.
Will have to try lowering the AV value like you suggested.

...and interresting quote btw

QuoteOriginally posted by Wheatfield Quote
That's a combination of somewhat over exposure in that area combined with veiling flare.
The fringing is, I suspect, just a typical byproduct of the former.
This is a poster image for why I don't buy anything other than Pentax glass, and why I stay away from zoom lenses in general.
I can understand why you would go for pentax only lenses, but I reacon the prices are also higher for those. I am considering another prime... some day.

QuoteOriginally posted by Lowell Goudge Quote
The only way to stop blown highlights is to either underexpose to Preserve them or add some front lighting, either with flash or reflector
This must be why all flash taken images I have seen, usually look good, edge wise.
04-27-2011, 04:23 AM   #10
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QuoteOriginally posted by mikknu Quote
Hello

I've been searching around to find an answer to what I think is fringing. But I have uploaded a picture of it. Hoping someone here can tell me what it is and how I can combat it.
It's the glow going from the neck (right side), running down the shoulder and arm of the girl in the picture. It's kinda annoying, anyone know how to get rid of it?
From the photo, it looks like the light source is almost in front of the girl (back is completely in shadow) which means your camera is pointing almost into the light source; this maybe the source of your issues. If you have a hood, it needs to be used or have the light more to her back.

I have a lens that does the same thing wide open (ghosting) in very bright light and almost gave up on it. However, I found using an 81B filter and hood actually helped out. But simply having the light source coming from behind the camera also solved the problem.

In such bright lighting, I am surprised you used ISO 400 instead or something like 100 and aperture setting at f3.2 instead of a stop or 2 down, which would have helped with the "light fringing" issue...
04-27-2011, 11:52 AM   #11
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QuoteOriginally posted by theunartist Quote
From the photo, it looks like the light source is almost in front of the girl (back is completely in shadow) which means your camera is pointing almost into the light source; this maybe the source of your issues. If you have a hood, it needs to be used or have the light more to her back.

I have a lens that does the same thing wide open (ghosting) in very bright light and almost gave up on it. However, I found using an 81B filter and hood actually helped out. But simply having the light source coming from behind the camera also solved the problem.

In such bright lighting, I am surprised you used ISO 400 instead or something like 100 and aperture setting at f3.2 instead of a stop or 2 down, which would have helped with the "light fringing" issue...
That shot was taken with the hood on.

Can't really say why it was on ISO 400, course I was fairly sure I had set it to ISO 100. I did do some experimenting while I was out that day, so maybe I was testing TAv at the time.
04-27-2011, 12:57 PM   #12
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QuoteOriginally posted by mikknu Quote
That shot was taken with the hood on.

Can't really say why it was on ISO 400, course I was fairly sure I had set it to ISO 100. I did do some experimenting while I was out that day, so maybe I was testing TAv at the time.
Your EXIF data says ISO 400...

Here is what is happening in your image: Chromatic aberration - Wikipedia, the free encyclopedia - you can see all the CA on that right side of person.

I think your focus is also a little loose. Take the picture again if possible, but have the light source behind the camera... try smaller stops, f5.6-7.1 - you will still be able to achieve a nice Out of Focus (Bokeh) background by moving in closer to girl and zoom out a little to compose image...

Good luck...
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