I've had this combo for about 5 months. I consistently get very soft photos of action at f/2.8 using AI Servo. Stationary pictures aren't so bad - not perfect but much better than moving target. Am I asking too much from this combo? I think a relatively new camera body and an L lens should produce a sharper image. If this is about as good as it gets, then I'll sell it and let someone else be happy with the result. For me, this doesn't work. I can't crop the image and retain something printable at a reasonable size.

Below (I hope - haven't tried to link photos in this way) is one example.

First - the whole shot showing AF Point - taken AI Servo, ISO 200, 1/3200 f/2.8 AV. Center point active only.

Check the grass to see if the camera back or front focus... if so, you need to do some micro adjustments or send the stuff off to Canon for adjustment.

To me, it looks like the camera backfocus. You might try to shoot a few in a burst to see if the camera will acheive focus...

Should've added additional information:

1. That was taken in H-Burst and is the second frame of 5. All 5 have the same softness, and all 5 have accurate placement of the center focus point.

2. The camera and lens just came back from Canon - I sent it to them 2 weeks ago out of sheer frustration at not being able to troubleshoot it myself and it's gotten no better. This was my first shoot since it's return on Tues Nov 3. It came back from Canon with a setting of -4 for this lens.

3. I've heard (and I'm no pro) that grass is the toughest thing to use as a measure of front / back focus - the blades are too hard to distinguish as sharp vs. not sharp. I tend to agree with that statement.

Thanks again for the response.


WebDog wrote:
Check the grass to see if the camera back or front focus... if so, you need to do some micro adjustments or send the stuff off to Canon for adjustment.

To me, it looks like the camera backfocus. You might try to shoot a few in a burst to see if the camera will acheive focus...

If it was me, I'd shoot at F4 or F5.6 for increased DOF. In this light you still have plenty of headroom for a fast shutter speed.

It should focus better than that. Most likely the camera is out of whack, though the lens can be affected.

EBH

I think its a DOF issue... I think your DOF is just too shallow to expect nailed focus and sharpness of a fast moving object. Additionally the lens isn't going to be as sharp racked out at 2.8 as it might at f/4 or f/5.6 even with stationary objects.

So what happens in circumstances where I need f/2.8 to achieve SS?

I've heard this suggestion before, and while it would likely improve the sharpness, I'm one who thinks that if a lens is F/2.8 and has the L label, it should actually work at f/2.8.



Gochugogi wrote:
If it was me, I'd shoot at F4 or F5.6 for increased DOF. In this light you still have plenty of headroom for a fast shutter speed.

That's why I sent both the camera and the lens to Canon NJ, and this is how it came back. I'm very underwhelmed and trying to decide on next steps.

EB-1 wrote:
It should focus better than that. Most likely the camera is out of whack, though the lens can be affected.

EBH

The DoF argument is silly. At 2.8, it should be sharp, and your focus should be able to track it. Try this. Check your series of 5 and see if the lens is consistently back-focused or front focused. If they are, then you know it's just a bac/front focus issue. If your focus is all over the place, then you know it's a tracking issue.

If your camera supports adjustments, play around with it and see what you can achieve.

You should be able to get much better than this.

Cheers,
Thomas

Check out the sharpness difference between 2.8 and 4 or 5.6 on this lens:

http://www.slrgear.com/reviews/zproducts/canon70-200f28/tloader.htm

Regarding DOF - the white line at the very bottom of the frame is the top of the goal box. This in't a full sized field so it isn't 18 meters out, but it is probably about 12 meters. So she's somewhere between 50 - 60 feet away from me (I'm about 6 feet from the end line).

The DOF calculator that I use says at 50 ft, 200mm, 1.6 crop and f/2.8, I should have about 2 feet of DOF- 1' in front and 1' behind.

With 2 feet of DOF, do you think that's the problem?

If I were dealing with inches of DOF, I'd completely agree. With a foot on either side? I'm skeptical.

And regarding 2.8 vs 4 / 5.6. I agree. But this is an L lens that isn't cheap. If it doesn't work at f/2.8, don't sell it - make it f/4. I had a 70-200 f//4 that was awesome, but it was f//4 and couldn't deal as well with lower light. I "upgraded" to this lens, but so far, the 50d / 70-200 combo has been far from an upgrade.

RichardLavigne wrote:
I think its a DOF issue... I think your DOF is just too shallow to expect nailed focus and sharpness of a fast moving object. Additionally the lens isn't going to be as sharp racked out at 2.8 as it might at f/4 or f/5.6 even with stationary objects.

I have to be honest, I have no idea what that graph means.

ratherfish wrote:
Check out the sharpness difference between 2.8 and 4 or 5.6 on this lens:

http://www.slrgear.com/reviews/zproducts/canon70-200f28/tloader.htm

I share your frustration and the frustration of anyone who has focus issues with their equipment. First lets talk about your exposure setup. Per the EXIF your shooting at 200mm wide open , 2.8. That is not providing you with any margin for error at all. In these lighting conditions you could well afford to drop your ISO from 200 to 100 and shoot AV with a maximum aperture of f5.6 or less, you will still have plenty of shutter speed to stop this motion and hopefully you will end up with a bunch of shots are f4 or f8 which will give you some depth of field. I copied your full size jpeg into CS4 and took a hard look at it. A line of grass just behind her feet is clearly in focus so you need to spend some time with a static set of objects on which you can get some microadjustment done. If you shoot a lot at 200mm then MA the lens there. MA and zooms don't necessarily mix well because the focus will shift as you change the focal length but with a 70-200 and smaller f-stops you should be alright. I wish I was there to help you but it is going to be ok, really. Some exposure work, some MA, and some patience and it will work.

Dave

The culprit here is misfocusing, one explanation could be because the AF point had hardly any contrast to lock on to, I think you would have had better luck if your point was on the shirt rather than the shorts. If everything has been calibrated then it's either user error or one or both of your items are messed up

Dave - thanks for the response.

Agreed that I could close down the aperture in this circumstance, but what happens in 4 weeks when I'm taking shots of her in a moderately lit auditorium as she dances in the Nutcracker? I'll be at 1600 or 3200 and still only get 1/500 or so - at best.

Second, I struggle with saying grass is sharp or not sharp - I'm looking for logos, letters or something else. I've looked at the 400 or so captures from today and the focus just isn't consistent. Even 3-4 frames into a burst, when all have 9+ spotting of the focus point, I get front, back and non focus. The only thing I don't get is sharp.

And re: Micro Adjust etc - I'd be OK with this if I hadn't spent 3 weeks trying it myself, then finally sending to Canon to let them figure it out, and having them send it back in this condition. Just not acceptible.

davenfl wrote:
I share your frustration and the frustration of anyone who has focus issues with their equipment. First lets talk about your exposure setup. Per the EXIF your shooting at 200mm wide open , 2.8. That is not providing you with any margin for error at all. In these lighting conditions you could well afford to drop your ISO from 200 to 100 and shoot AV with a maximum aperture of f5.6 or less, you will still have plenty of shutter speed to stop this motion and hopefully you will end up with a bunch of shots are f4 or f8 which will give you some depth of field. I copied your full size jpeg into CS4 and took a hard look at it. A line of grass just behind her feet is clearly in focus so you need to spend some time with a static set of objects on which you can get some microadjustment done. If you shoot a lot at 200mm then MA the lens there. MA and zooms don't necessarily mix well because the focus will shift as you change the focal length but with a 70-200 and smaller f-stops you should be alright. I wish I was there to help you but it is going to be ok, really. Some exposure work, some MA, and some patience and it will work.

Dave

I've got captures with focus point on the letters - bright white against dark blue - and same result.

Dawei Ye wrote:
The culprit here is misfocusing, one explanation could be because the AF point had hardly any contrast to lock on to, I think you would have had better luck if your point was on the shirt rather than the shorts. If everything has been calibrated then it's either user error or one or both of your items are messed up

Sorry. It's a blur index graph of that lens at various apertures and focal lengths and from edge to edge. Use the sliders to see the results. Purple is sharper than blue. Here's the full review on that lens:

http://www.slrgear.com/reviews/showproduct.php/product/72/cat/11

volyrat wrote:
So what happens in circumstances where I need f/2.8 to achieve SS?

I've heard this suggestion before, and while it would likely improve the sharpness, I'm one who thinks that if a lens is F/2.8 and has the L label, it should actually work at f/2.8.



Gochugogi wrote:
If it was me, I'd shoot at F4 or F5.6 for increased DOF. In this light you still have plenty of headroom for a fast shutter speed.


At the risk of sounding overly snarky... are you not aware that photography is all about making choices for your exposure... all of those choices require have advantages and disadvantages and you have to make concessions for what you are trying to accomplish in your image and your exposure.

Let's look at the argument another way and see if it makes sense... Imagine someone posted the exact same picture, but told you they had shot it at ISO 1600, 1/3200, f/8 and they were complaining that they thought the the noise in the shot was excessive... Your first reaction would be, "well, why'd you shoot it at ISO 1600?" and if that person then said, "well I have a 1 series and there is still some noise present. I think that a 1 series professional camera should be able to shoot at 1600 just as good as it does at 100".. you'd say, this guy is crazy, he obviously doesn't understand that there are drawbacks and consequences that will result from that decision. We all understand this when it comes to ISO... i'm sure you do too... when you push equipment to its absolute limit... even the best professional equipment you are going to have some drawbacks... in the case of aperture, you are going to lose some sharpness. As others have said... you have plenty of room in terms of shutter speed, so you could shoot that at ISO 400, 1/800 and f/5.6 have still stop all of that motion with a sharper image... why does it HAVE to be shot at f/2.8?

My 20D and 40D + 70-700 2.8 tie with my 17-40 as the most used setup.

If I am going out with one lense/body, it is frequently the 70-200. You are having equipment (i.e. calibration) or user issues.

I'm not an expert, but I do have this same camera and the Sigma 70-200 f/2.8. I have been able to get nice sharp images at 2.8 from the 50D no problem, and also on my previous 30D with the same lens. If my Siggy can do it, I'm sure the Canon can. I can't speak to the Canon lens directly, but from the image that you have posted, it clearly looks like the lens is focusing slightly behind the subject. There should be lots of contrast there for proper focus, so I think you can rule that out.

One thing that I have did learn from lurking in the sport shooter pages here, is that to get best results when shooting sports, you really should have the focus and shutter buttons separate from each other. Maybe this is how you do it, but you have not made mention of that. I will say that when I moved to that method of focusing I saw a drastic improvement in my keeper rate. Once I got used to the setup that is.

If all else fails, I'll trade you the Sigma for the Canon...

df