10D & 28-135mm. Colour fringes on highlight areas

[steve_bright1]

This is my first forum thread - please be gentle with me.

<p>I have some strange colour fringes that are appearing adjacent to

highlight areas in my images. I've attached a sample image, taken

with my EOS 10D, down-sized to 600 pixels wide. I've highlighted a

number of areas as white boxes, and these sections are shown

separately, magnified by a factor of two.

<p>Most of the colour fringes are near the edges, red on the left,

purple on the right, but there's even a slight fringe towards the

middle.

<p>If it was a film camera, I'd suspect chromatic aberration from a

really poor lens, but the body is digital and the C.A. is at a level

far worse than I've seen with any other lens. Is there another

explanation? Perhaps digital artifacts from the anti-aliasing filter?

Is something faulty?

<p>Here's the technical info:<br>

<table><tbody>

<tr><td>Camera</td><td>Canon EOS 10D</td></tr>

<tr><td>Lens</td><td>Canon 28-135mm IS USM</td></tr>

<tr><td>Focal length</td><td>28mm</td></tr>

<tr><td>ISO</td><td>100</td></tr>

<tr><td>Shutter speed</td><td>1/6 sec</td></tr>

<tr><td>Aperture</td><td>F22</td></tr>

<tr><td>Size/Quality</td><td>Large/fine</td></tr>

<tr><td>Color space</td><td>Adobe RGB</td></tr>

<tr><td>Parameters</td><td>All normal</td></tr>

</tbody></table>

<p>The full image:

<p align="center"><img

src="http://www.stevebright.com/photonet/IMG_2771.jpg">

<p>...and the small sections:

<p>

<img src="http://www.stevebright.com/photonet/IMG_2771a.jpg">

<img src="http://www.stevebright.com/photonet/IMG_2771b.jpg">

<img src="http://www.stevebright.com/photonet/IMG_2771c.jpg">

<img src="http://www.stevebright.com/photonet/IMG_2771d.jpg">

<img src="http://www.stevebright.com/photonet/IMG_2771e.jpg">

<img src="http://www.stevebright.com/photonet/IMG_2771f.jpg">

<p>Thanks for your advice. I hope I haven't committed a gross faux

pas with all these images, but they are all quite small.

[PuppyDigs]

That's normal for this lens (and all consumer zooms). If you're going to be that critical, start saving up for primes or L series zooms.

[gerry_szarek]

True landscape photographers only use primes. Other problems will be non uniform sharpness, light fall off in the corners, etc. Start saving your pennies. I can also recommend the 17~40F4L, and the 70~200 (all three), I find the L zooms to be pretty good (not as good as primes but what do you expect). Note they are not cheap!

 

Go to Luminous-landscape web site, for a review of canon gear zooms and primes!

 

GS

[Ken Katz]

"True landscape photographers only use primes"

 

http://www.johnshawphoto.com/equipment.htm

[ky2]

Kenneth-- that true photographer uses a Nikon ;)

 

Steve, you're shooting at f/22. Open up a bit or diffraction will kill your image. If you need to smooth water, use a quality ND filter.

[phyrpowr]

Steve,

 

I've blown up several of my shots with this combo, and just don't see the same problem, even washed out pure white surf

[steve_bright1]

Thanks for your responses.

<p>

I've read up on diffraction and as far as I can tell, that's just going to make the images softer rather than giving these colour fringes. Looking back through some images, I found another shot of a very bright white line next to a dark railtrack. The white line had a bright purple fringe and that was shot at F5.6. So I don't think it's diffraction, but I will definitely get an ND filter to smooth water.

<p>

Puppy Face says '...if you're going to be that critical...'. I don't really accept this argument. If this is chromatic aberration caused by a design limitation, then this is worse than I have ever seen, even from lenses costing a third as much. I find it difficult to accept that a company like Canon would be prepared to even put their name on it or release such a poor product to market.

<p>

This leads me to think that the lens is actually faulty in some way, unless...

<p>

The colour fringes do look quite similar to some examples of Moire artifacts I saw on the <a href="http://www.lashier.com/home.cfm?dir_cat=20523&gal_col=1">Lashier photography site</a>

[gabrielma]

Ow ow ow!! My eyes!!!<BR>

And I thought I had a so-so lens. My 28-135 takes better pictures than the one posted above. I do notice some chromatic aberration when I zoom in for a 100% close-up, which is a bit annoying, but that's because my 50 f/1.4 has spoiled me. I don't own any L glass (yet), but I can tell bad glass when I see it, and the lens used for the picture above is less than average. I mean, come on, I have a cheap 0.42 converter strapped on my 28-80 for when I really need to take a picture in a tight space without panning on my 10D, and the quality of that less-than-desirable combination is not as bad (a bit close) as above.<BR>

If I were you I'd exchange it or send it to Canon for repair/exchange.

[anthony_sanseri]

Isn't chromatic aberration a characteristic of the digital camera rather than the lens itself? If so, wouldn't the problem be with the 10D's sensor/image processor, rather than the lens?