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Olympus E-3 E-3 specific discussion.

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  #1  
Old 29th September 2012
Old John
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Exclamation Magenta fringes on high contrast edges

I have a problem with my E-3 which I have never met before, and I am wondering whether anyone else has ever seen the same thing. I would like to know what causes it and what the fix is.

I sometimes get magenta fringes on high contrast edges. Not always. It looks like chromatic aberration, but isn't. It happens anywhere in the picture. Investigating, I have found the following...

1) It varies with aperture. It is worst at full aperture and decreases as I stop down. I can't see it at f/5.6.

2) It is specific to the E-3 that I have. I also have a Panasonic DMC-GF1 and I do not get the fringes with this (using the same lenses). The E-3 and DMC-GF1 both have Live MOS sensors.

3) I used to have an E-1. Looking at some of the shots I took with this I can see no trace of fringes. Same lens, full aperture, comparable subject.

Does anybody have any clues, please?!
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  #2  
Old 29th September 2012
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Re: Magenta fringes on high contrast edges

I read a post of someone else having this ... sometime this week and dont know where sorry

but hope this post brings your thread to New Posts and someone reads this and can recall the other post
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Old 29th September 2012
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Re: Magenta fringes on high contrast edges

Pretty standard chromatic aberration, Panasonic sometimes correct this in camera. Were you using Raw or jpeg, what lens were you using and what processing software do you use?

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Old 29th September 2012
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Re: Magenta fringes on high contrast edges

I use RAW. Cameras do no processing on this.

Lens is Olympus 50mm f/2.0 macro in particular. Chromatic aberration with this lens? I don't believe it. Chromatic aberration varies over the field, normally being worst in the corners. I can get these fringes anywhere and they look the same regardless of position. And chromatic aberration normally stays the same as you stop down. And why did I not get them with the E-1. Not a trace. Also RAW, with identical post-camera processing. Other lens is a Leica 25mm f/1.4 D Summilux. Same fringes under same conditions.

For processing I use Photoshop CS4.

The E-1 uses a CCD sensor. The camera is inferior to the E-3 in many respects, but I regard the image quality as being better despite it having only 5 Mpx.

It would be interesting to see some pictures taken with the 50mm f/2.0 at full aperture on an E-M5. Manual focusing would have to be used.
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Old 29th September 2012
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Re: Magenta fringes on high contrast edges

CA is worse in digital cameras for some reason. My theory is that it is something about Bayer Array sensors and the demosaicing process. I wonder if CA gets worse as the pixel pitch of the sensor gets smaller, hence it's worse with a 10MP E-3 than with a 5MP E-1.

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  #6  
Old 29th September 2012
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Re: Magenta fringes on high contrast edges

You may be on to something, but I'm not sure. It doesn't explain why I get the fringes with the 10 Mpx E-3 but not with the 12 Mpx DMC-GF1. Also, I would expect to see them with the 5 Mpx E-1 but at a proportionally reduced level and I don't. And why do they disappear on stopping down? That is the oddest bit.

The fringes I get are so bad that I suspect that there is something wrong with my E-3 which is not a generic problem. If all E-3s do then same then a lot of the owners would be screaming.

As I said, I would like to see an image from using the 50mm f/2.0 at full aperture on an E-M5.

I am going to study my images a lot closer and expect to have more to say.
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Old 29th September 2012
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Re: Magenta fringes on high contrast edges

What are you processing the RAW files in? LR, for example, will by default fix M4/3 chromatic abberation for Panny lenses/Bodies.
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Old 29th September 2012
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Re: Magenta fringes on high contrast edges

I process my RAW files in Photoshop CS4, as I said before.

I know about LR's chromatic aberration correction. You can do that in PS also. It doesn't help, because it's not chromatic aberration from the lens.
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Old 29th September 2012
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Re: Magenta fringes on high contrast edges

I suspect Ian is partly right, but I'd put the culprit as the micro-lenses that create the bayer array. In which case the characteristics will vary across camera models - even if the underlying sensor is the same.

As for stopping down - well that changes the angles of incidence - so it may well impact results.

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Old 29th September 2012
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Re: Magenta fringes on high contrast edges

I was thinking about that myself, but somehow it doesn't quite seem to fit. If this is a generic problem for the E-3 I hardly imagine that Olympus would ever have released the camera.
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Old 29th September 2012
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Re: Magenta fringes on high contrast edges

Quote:
Originally Posted by Old John View Post
I process my RAW files in Photoshop CS4, as I said before.

I know about LR's chromatic aberration correction. You can do that in PS also. It doesn't help, because it's not chromatic aberration from the lens.
Sorry, didn't read the full thread
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Old 29th September 2012
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Re: Magenta fringes on high contrast edges

It might aid discussion if John was to post some examples including 100% crops.

However I've seen this on my E-3 where there is a high contrast boundary, and it can occur wherever in the image that boundary falls - particularly if one side of the boundary is considerably over-exposed. This fits the pattern for micro-lens aberration noted in these two articles http://www.dpreview.com/learn/?/Glos...rration_01.htm and http://www.fredmiranda.com/CFrx/ .

I have the feeling I've read a more detailed description elsewhere, but I can't recall the reference.

If we accept that it's aberration at the micro-lense then it would follow that the closer the light is to falling at right angles then the less aberration would occur, this would follow from the stopping down of the lens.

But I doubt if anything is ever quite that simple.

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  #13  
Old 30th September 2012
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Re: Magenta fringes on high contrast edges

Now we're getting somewhere

Last edited by Old John; 30th September 2012 at 10:01 AM. Reason: Sent by mistake
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Old 30th September 2012
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Re: Magenta fringes on high contrast edges

Now we're getting somewhere. I think you're right.

All the shots that show the effect have very bright white, either overexposed or verging on it. I attach two shots, both cropped.

The first shot, taken with the 25mm lens, shows the general effect. The limitations on the size of the files that I can upload do not allow it to show the fringes to best effect, but you can see them all right.

The second shot was taken with the 50mm f/2.0 macro. I changed the samples per inch to enlarge its apparent size. It is an extreme crop to show the detail. There is also some general light scatter (blue).

If the files are saved, they can be zoomed in on and the EXIF data examined.
Attached Images
File Type: jpg 25MM @ F-1.4 E-3 Cropped.jpg (96.9 KB, 22 views)
File Type: jpg Shot 2 Extreme Zoom.JPG (19.1 KB, 18 views)
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  #15  
Old 30th September 2012
Old John
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Re: Magenta fringes on high contrast edges

I attach the same scene as the first one of my previous post. This was taken using my DMC-GF1 in stead of the E-3. No fringes are visible.

Has anyone out there any information about magenta fringes using the E-5? I would like to know with a view to a potential upgrade.
Attached Images
File Type: jpg 25MM @ F-1.4 DMC-GF1 Cropped.jpg (94.1 KB, 10 views)
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