squirrelman

<p>I have both the Mark II and the 7D but only shoot birds with the 7D due to the extra length I get, which on my 100 - 400 L lens is significant. I see no reason to use full frame and lose the extra length as I shoot mostly wild life and birds. Full frame as on the Mark II I use for portrait and wide angle and landscapes.</p>

Thanks, Julian. According to one of those links, it clearly appears to be refractions caused by the UV filter in conjuction with a longer zoom lens. Easy enough to test this. Will let folks here know what I find later today.

Thanks, that last link was very helpful. Apparently the "bad bokeh" on this lens is more prominent at wider apertures, but fortunately only under certain lighting and pattern conditions.

Thanks folks for your responses. I just spoke to someone who owns the same lens, and he gets the same effect under certain types of conditions. He says "They seem to come from taking pictures of high-contrast parallel structures (leaves/gras in sunlight). Due to the blur some areas of blur overlap and generate a higher brightness than you'd expect and since you have nearly parallel structures to begin with the overlap patterns look non natural."

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I would agree at this point that it can't be the IS.

Any suggestions for reducing or eliminating the strange bokehs

sometimes seen in blurred backgrounds on photos taken with this lens?

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It doesn't always show up, and I'm usually able to eliminate much of

it with some post processing tricks, but it would be preferable not

to have to as it can be very time consuming.

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You can see a sample of what I am talking about in <a

href="http://www.newyorkslime.com/images/woodpecker-unedited-

01.jpg">this unedited frame.</a>

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Not sure if it's a lens effect or caused by the IS technology, but it

only effects blurred areas so I'm suspecting the IS.

Very interesting explanation Tim, expect I'm not buying into it as I've seen the same sort of wierd things happen to shots taken with film.

I think Canon may have errored with this one. It seems to fit a relatively small niche and for the $3,500 price I can't see a 20D user getting it. Even if I didn't own a 20D, I would probably pass on it.

For what I shoot (lots of critter closeups and portraits) I don't see a compelling reason to upgrade. Plus, I only bought my 20D a few months ago!

All forms of photography manipulate images beyond what the human eye experiences. Different films produce different grains, varying degrees of dynamic range, different color castes and biases, varying degrees of black and white contrast and toning or color saturation, etc. Lenses also play a significant role in altering images.

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And both film and digital photographers extensively post process their images. The site definition here at photo.net of manipulation refers to going beyond these usual techniques (see the definition for details). So I believe an effect created by a lens itself would not be considered manipulation.

I seriously doubt that the camera being digital played any serious role in making this image look the way it does.

A fence could indeed be one element causing the light to "wrap" and distort, but it also looks like horrible lighting conditions with a combination of both sun spots/glare and heavy shadows and a resulting errant underexposure.

Just about any animal photo will do provided it will make someone

smile!<div></div>

I own a 20D and have not seen such fringing on correctly exposed photos. I also just checked some moon shots and strongly backlit shots taken in the daylight, and they look fine too. By the process of elimination it sounds like the lens.