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20D and 24-70 2.8L focus issues??!!??
Old 06-29-2005, 02:52 AM   #1 (permalink)
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Anyone have the same gear experiencing focus issues?

I bought my 20D and 24-70 2.8/L about 5 weeks ago. I noticed that the autot focus was wildly inconsistent. SOme shots were tack sharp most were slightly to way off. As if I was drunk! So I brought my gear to Canon (luckily my office is just a few blocks from the service center). They took it in and and had it ready the next day. At first I was impressed, fast service and they quickly identified the problem. They said my camera body was fine but the lens had to be totally recalibrated.

I actually trusted that everything was ok. I shot a job with it and 75% of the shots were soft!!!!!!!!!!!!! Yes, the inconsistent focus issues were gone but the shots were consistently slightly off!!!!!!!!!!!!!!

Needless to say, the gear is back at Canon.


Anyone else experience this?

-Chris
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Re: 20D and 24-70 2.8L focus issues??!!??
Old 06-29-2005, 08:57 AM   #2 (permalink)
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Bad batch released on some of the L series lenses recently, had similar problems occuring with people who had 24-70's and 70-200 2.8 IS's.

Happens from time to time, but canon right on top of it

JasonNJ
GPCB
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Re: 20D and 24-70 2.8L focus issues??!!??
Old 07-02-2005, 06:17 PM   #3 (permalink)
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A few points and questions:

1. Were you shooting RAW or JPG. All digital cameras that I've shot with including the 20D are soft right out of the camera if you shoot JPG and have all the parameters set to their lowest setting. If you shoot RAW, then you have direct control of the data and can do some sharpening right in the converter, although it better to wait till later in the workflow.
2. What shutter speed and focal length were most of the "soft" shots. I other words might it not be a focus issue but just the fact that you're not steady enough handheld. That is a major problem for me. If I shoot with my 70-200 2.8 and I'm shooting handheld, let's say 1/125 and at 125mm, all of the shots are soft. But if I shoot the same shots with a tripod, all the shots are right on and sharp as a tack. I then have to soften the female shots because they're too sharp.
3. How do you focus? Do you point, for example, focus on the eyes, lock the focus and then recompose? If so, this is a sure fire way to get lots of soft shots because when you recompose the the distance to the eyes of the subject from the camera "film" plane are now different, and DOF can get you.
4. Are you making sure you get a focus lock? For example, on the 20D, do you assume you have a lock, when the red square flashes for the focus point, or do you wait for the green light to light up. You can shoot as soon as you get a red square, but true focus lock is not till the green light lights up. I've noticed times when there is a difference in the times when this happens.

But by and large, I've found 2 and 3 to be the problem more often than not.

Cheers,
rfs
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Use only one...
Old 07-03-2005, 10:14 AM   #4 (permalink)
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of the focus points, i.e.; center is what I use. Turn off all the other focusing points, the camera cannot make up its mind which point to focus on, even when you lock it sometime it quickly stutters back and forth. I like to frame, compose, move the center over the eye, focus and lock, back to frame and snap. Sharp everytime. When I got mine I had the same problem, as have many other 20D owners... David Mecey uses the focus point in upper vert frame, or horiz right, that is also a good choice, just remember where you are hot; it will always be the one that flashes red in the viewfinder.

Robert
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Re: 20D and 24-70 2.8L focus issues??!!??
Old 07-03-2005, 03:03 PM   #5 (permalink)
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I've been shooting for 10 years and I've never had this much of a problem with soft images. I'm convinced it's a mechanical failure.

I know it's not a shutterspeed issue. I had exposures at 1/250th F5.6 and they were still soft.

My camera and lens is still at Canon. I called on Friday to check on the status and they are still working on it. [img]/ubbthreads/images/graemlins/frown.gif[/img]

I've already made arrangements to swap the whole setup from Calumet if it doesn't come back from repair at 100%.

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Re: Use only one...
Old 07-03-2005, 03:05 PM   #6 (permalink)
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I've experimented with all of the focus points. Unfortunately, all of them exhibit the same problem.

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Re: 20D and 24-70 2.8L focus issues??!!??
Old 07-03-2005, 06:25 PM   #7 (permalink)
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I'd be interested to hear how things turn out. I know lots of photographers who have shot many years who have had focus issues when coming to digital so that's why I pointed out the 4 items in my list.
Good luck with the camera. I know that I've had exceptional results from my 20D so if you have a good one (and a good lens), then you'll get great shots.



Cheers,
rfs
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Re: Use only one...
Old 07-04-2005, 05:38 PM   #8 (permalink)
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Have you read the manual that came with your camera?

I've experienced the 20D to be much more accurate than the 10D.. however, it isn't perfect in all situations..

Certain light is dificult for any AF system. like shade.. it is a low contrast light that may not yield the most favorable results for you.. however, there ways around that... on your 24-70 L lens, there is a ring towards the front end of the lens...this is called the "manual focus ring".. and with the 24-70 L, even in auto focus mode, you can over ride the camera's "logic" and touch up the focus yourself..

Another way to help you out is by using custom function #4 set to setting #1.

This provides you with full control of the shutter release, and auto focusing opeations of the camera simply because the two functions are not controled by the same button.. instead, the shutter release becomes just a shutter release, and auto exposure lock..like when using AV, or TV mode.. The focus control is in the back of the camera, ..the one by your thumb that looks like an astrisc * (sp?) so, you can compose a shot..and focus on the spot you want, and recompose the shot slightly, and take the picture you want... which is the way I have all my cameras set up like.. It takes a little getting use to but once you have it down, there is no going back..

Also,.. when in tight,..a model's eyes are sunken in a tad from her eye brows..and that may make the shot appear soft.. which is a good time to use manual focus.. I shoot manual focus for the majority of my people pictures, and much of my sports...and it is a lot easier on the 20D than it was on the 10D..or even the D30.. the matt part of the screen is pretty clear compared to the center spot, which is clear..

The thing to keep in mind is that every lens I have had has had AF issues which were mostly me doing the wrong thing.. Every camera is different,...every lens reacts differently...it's just a matter of learning how to use them..
'
Try that out...and see what happens.. (sometimes, hitting the back button more than once helps a bit)

JP
I had to MF this shot because the water spray and mist in the foreground of the shot "confused" the AF into massively front focusing......still, she is a tad soft in the shot because she is moving, and I'm shooting at 1/30th to get the water more smoothy looking..Yep!

 
 
Re: Use only one...
Old 07-06-2005, 04:12 AM   #9 (permalink)
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I do the same thing too. On my Canon 1Ds. Its the answer!!!!! This shot was done with my old 10D. I sold it and am waiting a year or so after the Canon 1Ds mark 2 came out so soon.


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Re: Use only one...
Old 07-06-2005, 12:27 PM   #10 (permalink)
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[ QUOTE ]
I like to frame, compose, move the center over the eye, focus and lock, back to frame and snap. Sharp everytime. When I got mine I had the same problem, as have many other 20D owners... David Mecey uses the focus point in upper vert frame, or horiz right, that is also a good choice, just remember where you are hot; it will always be the one that flashes red in the viewfinder.

Robert

[/ QUOTE ]

Actually your technique, while widely used, will not product sharp photos all the time. If it works for you, then you've been lucky and/or you've been shooting most of your shots at f8 or f11 for f16 where you had enough DOF to compensate. But here is what happens with the method you are using. When you lock the focus on the eyes, lets say they are 10' from the sensor plane of the camera. Now you move the camera back to frame the shot while holding. The distance from the sensor plane is no longer 10' in many cases. Depending on the way the scene is organized there could be as much as a foot or more variance. So if the DOF is not 1', in this example, you would have a soft photo.

Here is a link that discusses the problem a bit more and shows a diagram of the process:

http://tinyurl.com/8ygpq

Now don't get me wrong. I'm not saying that one should not use the technique you do. I use it myself all the time, but primarily I'm a studio shooter and with strobe lighting I'm usually shooting at f8 and f11 so DOF compensates. But when I'm shooting wide open (f2.8, for example). Then I compensate by stepping forward or backward, based on experience as I do the recompose.

Cheers,
rfs
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