AF with Sigma 17-70 and/or 40D...

topcatproduction

topcatproduction

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Hi, I was having a play yesterday and reminded me that I really struggle with getting well focussed shots from my 40D. I can't remember if it is as bad when I use my 70-300 but I only had my 17-70 with me yesterday.

It is ok when stationary but when trying to focus on a moving subject it seems very poor and basically want to know if it is my camera, lens- or very likely me! Apart from the first (still) they are all oof, and the first isn't exactly tack sharp, the Sigma is ok and can deliver sharp shots but doesn't all the time.

As I'm trying to work this out not looking for critique I'm hoping this is in the right section!

Some examples from yesterday, all shot using single centre point AF, AI servo and continuous drive. Any ideas where to start getting better results?!

IMG_9510.jpg


IMG_9515.jpg


IMG_9502.jpg


IMG_9503.jpg
 
The second one really looks like motion blur,what shutter speed were you using.:)
 
Sorry forgot to say! Shutter speeds were between 1/250 and 1/320 on these, which I thought should have been high enough- but maybe I was wrong. I keep assuming things that I look back on as stupid mistakes with my photography! I dont get much time for it and when I do I always forget to change some setting that makes a rubbish set!
 
I would raise the shutter a good bit for dogs running around & see how it goes,put it on shutter priority & try it.:)
 
Yep i know what you mean,it costs nothing to fire off a few hundred shots as once they have grown its too late.:)(y)
 
Were you giving the focus system time to settle before shooting? You generally need to track the target for, say, a second or so before shooting to get a sharp shot. USM/HSM lenses settle quicker, but it's true in all cases to some extent.

In addition to that and the comments above, I've not found this camera/lens combination to be great at tracking moving subjects. That's true of most other non-USM/HSM lenses too.
 
gcogger said:
In addition to that and the comments above, I've not found this camera/lens combination to be great at tracking moving subjects. That's true of most other non-USM/HSM lenses too.
Click to expand...

I'll be watching this thread with interest. I've never been happy with my Sigma 17-70, for the same reasons as the OP.
 
Yes I would focus then use continuous drive to fire a few off and the first is always ok then they go downhill as if the lens or camera can't keep up. For stills and macro the 17-70 is really good, excellent focal range and decent aperture, but as said- not sure if it is the lens or camera that struggles with speed.

Saying that when I took my 40D and 70-300 IS USM to the grand prix this summer it kept up a lot better than the sigma, and the cars were going quicker than the dog! It wasn't perfect though, but I think that was down to 1. being stretched at 300mm which is known for being soft, and 2. shooting through a chain link fence :( any thoughts?

Just a quick example using the 70-300 with the same camera:
IMG_7784.jpg
 
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