50D Servo Question

On a couple of occasions while shooting with my 50D in Servo I have noticed that the image in the viewfinder starts chattering, ( jumping around like when movie film became disengaged from the projector sprockets ) The photos have not been affected. Has anyone experienced this? Is it time to call Canon? This has happened a few times with two different lenses, my 100-400 and my 70-300.

Yikes... that doesn't sound good.

Is this with just one of your IS equipped lenses? The symptoms sound a lot like a failing IS unit.

JeffreyG wrote in post #7096033
Is this with just one of your IS equipped lenses? The symptoms sound a lot like a failing IS unit.

It has happened with two IS lenses. That is why I'm inclined to think it may not be an IS unit

Larry Weinman wrote in post #7096068
It has happened with two IS lenses. That is why I'm inclined to think it may not be an IS unit

I still think the shaking is caused by the IS unit, but if it occurs on multiple lenses then it sounds to me like the 50D is giving the lens bad commands. Can you get a non-IS lens to do it?

JeffreyG wrote in post #7096088
I still think the shaking is caused by the IS unit, but if it occurs on multiple lenses then it sounds to me like the 50D is giving the lens bad commands. Can you get a non-IS lens to do it?

That's an interesting idea. I'll try that later today. I'll also try it with the lenses where the problem was noticed with the IS shut off. Maybe I have two lenses with failing IS units.

Larry Weinman wrote in post #7096114
That's an interesting idea. I'll try that later today. I'll also try it with the lenses where the problem was noticed with the IS shut off. Maybe I have two lenses with failing IS units.

Yes, try a process of elimination. It would be a big coincidence to have two IS units failing at once, but not impossible. Narrowing down the root cause will save you sending too many items to Canon.

Are you sure it isn't just the camera's AF system trying to lock onto something that it can track? Are you trying to shoot still subjects with AI Servo?

rdompor wrote in post #7096123
Are you sure it isn't just the camera's AF system trying to lock onto something that it can track? Are you trying to shoot still subjects with AI Servo?

^^ +1

So far I have tried it on my 100-400 with IS and with IS shut off, my 70-300 with and without, my 50mm f 1.4, my 35mm 1.4 and 300mm f 2.8 with and without IS. I tried doing a 180 degree fairly fast pan which might seem to be allot but this is what I do normally with birds in flight. This "phenomenon" as Canon would refer to it happens on all lenses, it is most pronounced on the long lenses. I then tried a few of these same lenses on my 40D with Servo and noticed the same thing to a lesser degree. There is sporadic noise coming from within the lenses, ( not IS noise ) probably as they adjust to the different distances. I couild not replicate the jumping around in the vieefinder as that only seems to happen in very bright light ( yesterday when photographing Trumpeter Swans in bright light reflecting off snow )It is overcast and snowing here today. I don't know at this point if this is normal since my 40D was doing pretty much the same thing. Any ideas would be appreciated

Do you have "all" focus points active? Or just the center focus point?

Just center point

OK, it happens on all lenses, so it's your AF rather than IS, and it happens to some degree with the 40D, so it must to some degree be "normal". It is likely related to your AI Servo AF trying to focu on the moving object -- you say birds in flight -- are these birds close enough to fill the center of the viewfinder?

Maybe you could test things out on some things that are bigger, such as cars driving down the road. If the AF is jumping around when you are focusing on a fairly large object, that would be a problem, but you want to compare with the 40D to see if it's out of whack with the 50D.

With small objects, AI Servo will try, but sometimes fail, to focus on the object, and may hunt back and forth and around the center. The actual "point" of focus is larger than the little dot that flashes on the screen, and so you may see the camera focusing on something a bit off-center.

Birds in flight are tricky things and take practice. That's why I suggest testing and learning using larger objects, such as cars, airplanes, bicycles, boats, etc.

Larry,

Try using all focus points. I read somewhere that the AL SERVO works with all focus points active. Give it a try, and let me know.

Thanks!

I'll try the above suggestions as soon as it quits snowing here and the light lifts a little bit. I have been shooting BIF for quite a while now. I hesitate to use all focus points because if there is a busy background, as there was when I was shooting down at the river, the focus tends to lock on something in the background. All points works pretty well when I'm shooting the bird against the sky, otherwise center point works best for me. I'm beginning to wonder if the glare had something to do with it. I was shootiing large white Trumpeter Swans and they were standing on snow covered ice on a bright sunny day.