Why are these photos blurry?

[dtrachtman]

I have a Canon Rebel T3i. I have taken a number of group photos w/tripod, w/o tripod, w/flash, w/o flash, various apertures, many on automatic mode. All on autofocus. All of them come out fuzzy, especially the people on the ends. The attached might look ok small on this web page, but if you download it and look at it 100% you will see what I mean. I have two T3i cameras and they both yield the same results. I would probably get a better photo with a phone. Any ideas?

[dtrachtman]

I am the designated photographer at a big conference that my organization puts on and have to run from spot to spot and usually have little notice when a group will want a group shot. I don't have a helper, so it would be hard for me to carry around much more than a camera, extra lens, and a tripod. Maybe if I have more notice I can use some of the additional items you have mentioned. I can see why it would produce a better, more professional looking result.

[dtrachtman]

Hello all again,

I wanted to update this topic and see if anyone had any other ideas. I have now tried the following and none have solved the problem of the people on the sides of my group shots being blurry:

-Made sure the camera focuses on the faces in the middle in both auto mode and manual spot mode

-Used two identical Canon t3i cameras

-Tried smaller apertures and faster shutters

-Used a tripod

-Purchased and tried

a Tokina 11-16 lens

-Purchased and tried a powerful flash

I havent tried raw yet although I doubt it would make much of a difference in this case.

Below are a couple more examples. I had to crop one to get under the 5meg max.

[TCampbell]

You are getting an effect called "chromatic aberration" (often abbreviated "CA").  This can be fixed in software if you have the right software.

When light passes through glass at an angle (like a prism) the light bends (it's why a straw appears to bend if you look at it in a glass of water even though you know the straw is straight).   But blue light (shorter wavelength light) bends more than red light (long wavelength light).   

The edge of a single element of convex lens works like a prism and does this to the light.  The lens maker uses additional lens elements to try to correct for the problem.  It's possible to mostly correct it -- but almost impossible to be perfect.  Some high end glass does a much better job than entry-priced lenses.

Look at the woman on the far left on the bottom photo.  She's got a black jacket and a brooch.  Look at the left edge of that brooch and you'll notice it has a blue fringe.  Look at the right side of the brooch and you'll notice a red fringe.   That's the CA effect.  It's softening or blurring the quality of your image. 

Due to the way CA works, you'll find no effect in the center optical axis of the lens, but you will see the effect around the edges.  

Computer software can separate the color channels, then squeeze or stretch the channels so that they all exactly fit on each other, then recombine.

If you decide to search for a different/better lens, I would recommend renting so that you can evaluate the quality and make sure you've find a lens that meets your needs... then go buy the lens you like the best. 

[dtrachtman]

Hi TCampbell,

Thanks for the suggestion. If it were just CA, then if I looked at just one color channel in Photoshop, it should be sharp, right? It is maybe a little better, but still blurry.

Dan