Focusing with the Canon 40D.

glsammy · #1 (**permalink**) 17-02-2009, 04:53 PM

Recently I commented about a focusing problem with my 40D. At the time my camera was away being repaired, so I was unable to supply any sample images. The repair had nothing to do with the focusing issue, but I did ask them to double check it to ensure it was up to spec.
Today I got the camera back so I went out to try and get some shots to show what I'm experiencing.

Here is a sequence of 4 consecutive shots:

Now I was pleased in so far as I got the bird slap in the centre of the focus point. What I'm not pleased with is that not one of them is anyway near in focus. I was using my 1.4X TC, but I can assure you that it makes little difference with or without it.

Here's a shot with the lens on its own. This one isn't even head on!

I've not prepared these images in any way they're simply re-sized, whilst the shots form the 20D have been worked on. No amount of work will rectify the bad focusing!

The light conditions were not that hot, but they were no worse than when I was at Rufford Park last week when I got loads of similar shots using the same lens on my 20D, and just about all of them were in focus.

Shots from last week:

This confirms my feelings re this camera. It's auto focusing performance for moving subjects, especially coming towards the camera is worse than the 20D. That's progress for you!

NickCantle · #2 (**permalink**) 17-02-2009, 04:58 PM

Surprising that is Graham. I've had little qualm with the system whatsoever. Look at Roger's 40D

glsammy · #3 (**permalink**) 17-02-2009, 05:00 PM

Quote:

Originally Posted by NickCantle

Surprising that is Graham. I've had little qualm with the system whatsoever. Look at Roger's 40D

Show me some head on Images Nick.

Roger confirmed to me himself that on our recent trip to Rufford, he did notice badly focused head on shots.

Not everyone takes that many head on moving shots as I have lately. During normal use there is no problem, in flight shots I took today were fine. It's head on, straight at the camera where it shows this problem.

NickCantle · #4 (**permalink**) 17-02-2009, 05:04 PM

Quote:

Originally Posted by glsammy

Show me some head on Images Nick.

Oh I see what you mean. I thought you meant that the autofocus wasn't very good as you showed an image side on as well. What I'm going on is the fact that I was following swifts and swallows with my 400D in Spring and the 40D certainly outperforms that IMO.

By the way, where would I go to try out head on images? It would be interesting to try it for myself.

NickCantle · #5 (**permalink**) 17-02-2009, 05:05 PM

Quote:

Originally Posted by glsammy

Not everyone takes that many head on moving shots as I have lately. During normal use there is no problem, in flight shots I took today were fine. It's head on, straight at the camera where it shows this problem.

That's very true, the heads on approach seems to be quite exclusive to yourself! So what would be the problem then? Just an inability to judge and adjust to distances?

glsammy · #6 (**permalink**) 17-02-2009, 05:09 PM

I'm not by any means the only one who's noticed focusing problems with the 40D. This is part of the review of the 40D at Canon EOS 40D Digital Camera - Full Review - The Imaging Resource!

"However, there have been quite a few situations where the Canon 40D kept on seeking when the 20D just quickly found and locked focus, specifically when the 40D was in Multi-point AF mode. I've found a few situations where the Canon 40D just seeks and seeks, and never stops. Most cameras give up after a few seconds. This is the first autofocus SLR of any make that I've seen do this. You can turn Focus Seek off in the Custom Function menu, but that still doesn't stop the endless seeking. Oddly, this occurs more for me in vertical mode.

In horizontal mode, Dave had a heck of a time getting the Canon 40D's top center AF point to focus on Marti's hair during the indoor shots. Hair isn't the best place to focus, of course, but it works well enough when we do it with other cameras. In Dave's case, the camera said it was in focus, but it was either front- or back-focusing.

When shooting a soccer match in AI Servo mode recently, the Canon 40D had a hard time finding and keeping focus on my subject. It was usually okay if I could keep the player over the center point, but not always. It still randomly focused many yards behind a player for one frame, then snapped back to proper focus, then back out. Soccer is an extreme example -- and I am spoiled by shooting the 1D Mark II N, and even the 1D Mark III -- but the 20D does better than the 40D in these situations. I got better results shooting in AI Focus mode, which is probably more appropriate for a more random movement game like soccer."

I know exactly what they mean, my camera also does the endless backward and forwards without locking onto the subject.
Never happens on the 20D.

Ollie · #7 (**permalink**) 17-02-2009, 05:24 PM

Quote:

Originally Posted by glsammy

Show me some head on Images Nick.

Roger confirmed to me himself that on our recent trip to Rufford, he did notice badly focused head on shots.

Not everyone takes that many head on moving shots as I have lately. During normal use there is no problem, in flight shots I took today were fine. It's head on, straight at the camera where it shows this problem.

Yes I can definitely confirm that the 40D is not the best at head on moving subjects.

I was slightly at crossed purposes with Graham when he first mentioned this not realising that he actually meant head on. On my last trip to Rufford with Graham I had several head on shots where the centre focus point was dead on but the bird was definitely way off focus. The light was very poor at the time and I thought that was maybe the problem but I have since tried on my local patch in good light and again some of the head on shots were out of focus and at times the camera just kept focus seeking rather than locking on.

Anything slightly at an angle is fine it picks it up and locks on no problem and it's usually in focus.

It is possible to get head on shots in focus but the 40D makes it rather a hit and miss affair.

Roger

glsammy · #8 (**permalink**) 17-02-2009, 06:13 PM

Quote:

Originally Posted by NickCantle

That's very true, the heads on approach seems to be quite exclusive to yourself! So what would be the problem then? Just an inability to judge and adjust to distances?

Not sure Nick, but it's very frustrating. You can see that you've got the bird spot on. The shutter fires but it never locks on. If it ever does lock on then you'll have no problem, the whole batch would be OK. It's that initial locking on that seems to be the problem. It throws the lens into a constant backward and forward seeking mode and never seems to get there.
That sideways shot I posted was a bit of a red herring, no camera is perfect all the time, generally once an angle is there onto the birds, as in this one:

The performance is just fine.

I'd be interested to see if the 50D has the same problem. I'm seriously considering getting a 1D Mark II, purely to get over this problem as it's really bugging me! If the 50D was OK that could be a viable alternative.

DaiTheDragon · #9 (**permalink**) 17-02-2009, 07:10 PM

Graham, when you look through the viewfinder do you see the green focus lock light (the green light wont work with the TC attached). Have you tried using all focus points instead of center only. If there is some decent weather this week I will try and get some head on shots with my 50D to see what it's like.

Dai