Why does this photo look strange?

denniscloutier

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I recently got the Olympus 45mm 1.8 to use with my EPL2. I was out playing with it on an overcast day and I shot the attached photo. I was looking upwards into fairly bright clouds and trying to expose for the branches. As a result the background was very overexposed.

I was shooting 1/1250 of a second at F1.8 and an ISO of 200.

The branch I focused on looks reasonably sharp, and the colour looks fairly accurate. But the branches behind the focal plane have a green tinge. There also appears to be fringing around the branches. I don't know how well this is coming through on the jpeg but it is very evident when I look at the RAW file in Lightroom.

Can anyone tell me what is causing this strange effect?

Also, if anyone can tell me how to get rid of the two extra copies of the photo in the post, that would be appreciated too!

Thanks,
Dennis
 

supermaxv

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I see some purple fringing in the front and green fringing in the back, that looks like chromatic aberration to me.
 

denniscloutier

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I thought of chromatic aberration too, but I thought that was mainly a problem with short lenses? This was shot with a short telephoto, and most people seem to think that the Oly 45 1.8 is a good lens.
 

Markb

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It looks like chromatic aberration to me too. Try processing your raw file in Olympus Viewer. You can apply the in camera corrections in the raw developer and see if it makes a difference. I can't help with Lightroom.
 

supermaxv

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I thought of chromatic aberration too, but I thought that was mainly a problem with short lenses? This was shot with a short telephoto, and most people seem to think that the Oly 45 1.8 is a good lens.
If you do some googling you'll see plenty of reports of this happening with this lens, particularly at wide open. Doesn't mean it isn't good though!
 

phrenic

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Yeah it happens in scenes of high contrast (ie sky backlighting).
 

FastCorner

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If you look at pictures that people take of a LensAlign, you'll see the B&W alignment patterns they use show a magenta/green fringe depending on whether you're looking fore or aft of the focus point. While not desirable, this behavior is not atypical and basically what you're seeing here.

For these shots, you can convert to B&W and workaround the issue. :)
 

denniscloutier

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Thanks for your help. These images aren't keepers, but I was curious as to what was going on.

This is my first fast prime lens, so I have never run into this before.

Thanks all.

Dennis
 

rpress

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This is a classic example of longitudinal chromatic aberration (LCA); there are different focal planes for different colors. This is particularly hard to correct in post. Stopping down the aperture will help a lot.

Transverse chromatic aberration (TCA) is a lot easier to fix, and the Panasonic bodies/lenses correct for this automatically.
 

QualityBuiltIn

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It's not a fault or sign of poor lens quality, just a manifestation of the laws of physics; light with shorter wavelengths comes to a focus in front of the sensor while longer wavelengths try to focus behind the sensor. Same thing happens in your eye, just replace the word 'sensor' with 'retina'. Thing is nature would have stopped your pupil diameter way down under those lighting conditions.
 

RobWatson

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It's not a fault or sign of poor lens quality, just a manifestation of the laws of physics; light with shorter wavelengths comes to a focus in front of the sensor while longer wavelengths try to focus behind the sensor. Same thing happens in your eye, just replace the word 'sensor' with 'retina'. Thing is nature would have stopped your pupil diameter way down under those lighting conditions.
Better/different lens design would accomodate more wavelengths for proper correction and eliminate the CA. These capabilities are limited to a large extent by materials and tend to be expensive. Also the lens design may be free of CA entirely (like a mirror system ala newtonian, etc) but then other abberrations become a problem.
 

dhazeghi

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I thought of chromatic aberration too, but I thought that was mainly a problem with short lenses? This was shot with a short telephoto, and most people seem to think that the Oly 45 1.8 is a good lens.
Longitudinal CA is fairly common with fast lenses at wide apertures. This looks pretty typical. Edges with harsh transitions tend to bring out the worse.

Lateral CA is less specific to aperture, and is common among wide angles, though it can be seen with other lenses too.

The bad news is that while lateral CA can be automatically fixed in most post-processing software, longitudinal CA usually requires a fair amount of manual intervention.

DH
 

dixeyk

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Shallow DOF, must be shot wide open, high contrast...looks like CA to me as well.
 
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