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Old 3rd August 2011
Swordfish Swordfish is offline
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Diffraction effect?

I was initially pleased with the colourful background and contrast to an otherwise ordinary butterfly. However close examination shows the furthermost legs and proboscis are somewhat red/pink. My assumption is that this is a diffraction effect made noticeable by the vivid background colour, but I wonder - is this inevitable in this type of shot, or is it a function of the lens quality? Any views welcome.

This was taken with a 70-300mm @ 300mm



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Martin
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Old 3rd August 2011
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Nick Temple-Fry Nick Temple-Fry is offline
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Re: Diffraction effect?

Nice shot and lovely background colours.

Don't think diffraction is coming into play here - after all this was taken at F5.6. Quite a bit below where you would expect diffraction softening.

Isn't this just dof with the further legs going out of focus and colour coming in from the oof areas around it. Closing down the aperture a bit would probably have resolved it.

By the way it looks like the gallery software has resized the image down to its maximum height of 800, it's resizing software isn't gentle on image quality.

Nick
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Old 3rd August 2011
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Re: Diffraction effect?

I concur with Nick - it's just the background colour merging with the fine out of focus areas of detail in the butterfly. Diffraction is gradual and really only starts at f/6.3-7.1 and is only very noticeable at f/11-16 and onwards.

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Old 3rd August 2011
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Re: Diffraction effect?

Thanks for comments - probably right, its just the very thin members disappearing because of the dof. Smaller aperture may have helped, trouble is these things are never obvious until you're back in front of the laptop!

Nick - not quite sure I understand the comment re the software resizing the image - is there something I should be doing to control this?

Martin
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Re: Diffraction effect?

Quote:
Originally Posted by Swordfish View Post

Nick - not quite sure I understand the comment re the software resizing the image - is there something I should be doing to control this?

Martin
Well I may well be wrong but the resolution in the exif shows as 1280 by 960, whilst the size shows as 1067 by 800. Normally these two are the same.

So I made the guess that you originally posted the image at 1280 by 960 and the gallery software cut it down (after reading the exif) to 1067 by 800 'cos the software doesn't like a height greater than 800. Of course the discrepany may be from elsewhere.

Solution is not to post with a hight greater than 800, if indeed you did.

Nick
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Old 3rd August 2011
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Re: Diffraction effect?

Understood - I did indeed post at 1280 x 960. I guess you're saying that the gallery software does a less good job of resizing than say Photoshop.

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Martin
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