Autofocus vs. Manual focus on 10D

Hi all, I have a Canon 10D with 17-40/4.0L lens. My pictures come

out as to my expectations. A few things I notice can be better. My

autofocus is a little off. I have tested by focusing Manually and

with autofocus on the same point. My testing was mostlty done on

items with small/fine lettering. The hands down winner from my 100

pictures taken was me Manually focusing the lens. The difference is

measurable when I view the image at full resolution. I have read

everywhere that to get proper sharp photos, use manual focus? What

do you think

Here's one of my examples. The photo was untouched, it was just croped.

<p>Whenever I shoot macro, I use MF as narrow DOF leaves little room for error. MF is more precise as your brain determines the point of focus rather a CPU. With AF, the sensor locks on to the brightest and/or nearest point, not always what you want. Incidentally, the 10D's AF sensor is nearly twice the size of the AF rectangle, so even if you center it on the desired point of focus, it can easily grab a point just above, below or to the side. Check out the actual sensor coverage:</p> <img src="http://mk23.image.pbase.com/u30/chuckwestfall/large/18920257.10DAFCoverage.jpg">

Mine is an EOS 300D, which I believe you call the Rebel. It's very similar, in any case.

 

I don't find autofocus a problem, either with the 18-55mm kit lens, or my Sigma 70-300mm. It's just a matter of using the autofocus points properly. I was a bit dubious at first, but I have to admit autofocus works a treat. (I am assuming that your camera has autofocus points, in the SLR viewfinder.

 

The other factors are:

 

- depth of field required, which is a factor of the aperture selected;

- the available light, as poor light will aways impede your focus, whether you use manual or auto.

I believe if you read around here you will find that there have been problems with 10d's focussing accurately. Perhaps you should send it in to canon.

I have come across many AF cameras where the focus point with AF is different from that of the screen - manufacturing tollerances have a lot to answer for.

My experience with the 10D is that mine focuses accurately, but the focusing points are huge compared to the viewfinder indications (I'd estimate them to be about 3x larger).

 

It's very possible that the camera had locked focus correctly on something that is not what you expected at all.

 

With a camera like the 10D I find that it is hard to manually focus except when there's very little depth-of-field.

Bad exemple... What about trying the same example with a polarizer? Or do the classic

newspaper page from 10+ feet away.