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View Poll Results: Have you experienced focus problems with Canon EF lenses?
No - My EF lenses are near perfection 9 64.29%
No, but I wonder sometimes 2 14.29%
Yes, but Canon fixed the problem 2 14.29%
Yes, and Canon failed to fix the problem 1 7.14%
Voters: 14. You may not vote on this poll

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Old Mar 13, 2005, 12:46 AM   #11
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Sounding more like the mirror isn't returning to the proper position... and since it is a moving part, makes more sense in the scheme of things.

At 8.5 fps... one might expect problems with it.
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Old Mar 13, 2005, 6:48 AM   #12
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TDM_Canon_User wrote:
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Sounding more like the mirror isn't returning to the proper position... and since it is a moving part, makes more sense in the scheme of things.
You have to approach this issue methodically - I know what you think about 'test' charts but real-world pictures are not going to help you isolate this issue, but just show you the problems/results:

1. If the mirror does not 'pivot' back correctly (ie exactly 45 degree) -> Tests with charts will tell you wether the focus is off toward the top of the screen (or toward the bottom), since the AF is centered toward the middle and a 43/48 degree mirror will reflect this

2. Test charts are done in controlled condition and will tell if your camera has problem in low-light/low-contrast - since you set the lighting (variable and reproduceable) and the test patterns are fixed to the millimeters

3. If you keep shooting low contrast foliages (may be gently moving too) or foggy landscapes - we are not getting anywhere :?
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Old Mar 13, 2005, 10:14 AM   #13
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NHL,

Thanks for the map if the body. Yes, I recalled the secondary reflec mirror. Still, when you MANUALLY focus on something only the primary mirror and focus screenare involved. If both the manual and auto-focused image comes out NOT IN FOCUS, I am getting somewhere. Means the auto-focus mechanism is working just fine. That there is a physical defect somewhere in the two/three focus paths thatdonot match.

If the path between the "eye" and the film isn't equal - images on the "film" are not in focus. Thus, if the mirror is out of position when focusing the image will be hacked. This maladjustment is something that often happens to mirrors over time. My old T90 had to be adjusted, my AE1's did too.

What I have verified is:
1:manual focus doesn't achieve prime focus.
2: auto-focus matches a manually focused lens position.
3: image focus varies when auto-focusing multiple repeat images.
4: this is 1D Mark II number two that has failed this way.

Tim

ps: images with my 16mm have shown that in all cases images are focused well in front of the selected subject. Here's one practical example where the rocks are in focus but the subject bridge isn't. Hard to tell in this resize, but in the full image the rocks are fine, but the bridge is blurry. Dozens of images I took with the 16 and 24 that day shown the same ill-effects - foreground sharp, backgroud blurry.
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Old Mar 13, 2005, 3:34 PM   #14
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It gets more interesting...

I went wild and took several dozen full auto at high speed frames. About 150 frames. Then redid the tripod mounted distance focus test.

The latest images look better! Seems using the camera at full speed once in a while might be necessary to keep the mirror operating properly... I'm going to try again under similar light tomorrow morning.

Tim


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Old Mar 13, 2005, 3:53 PM   #15
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TDM_Canon_User wrote:
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ps: images with my 16mm have shown that in all cases images are focused well in front of the selected subject. Here's one practical example where the rocks are in focus but the subject bridge isn't. Hard to tell in this resize, but in the full image the rocks are fine, but the bridge is blurry. Dozens of images I took with the 16 and 24 that day shown the same ill-effects - foreground sharp, backgroud blurry.
Take a look at your picture...

The rocks have all the details whereas the bridge has no discernable contrast for the camera to focus on, and it's darker on top of that - Even an expert photographer would have problem focusing on the trees/bridge manually and the foggy mountain has no define edge...

Plus the glossy water does not help either

In this case I would use hyperfocal and mount the camera on the tripod for ultra-wide DOF... Nice cpmposition BTW too bad the weather didn't cooperate otherwise you wouldn't have any AF problem either :G
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Old Mar 13, 2005, 4:25 PM   #16
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Your missing the original point: my D60 does just fine focusing on these types of images, as did the 1D once upon a time (and maybe does again).

Besides, when the 1D says it focused on the bridge (focus confirmation in viewfinder), it wasn't looking at the rocks. The focal point was "SINGLE POINT", and I had it on the bridge. Beyond that - what's more contrasty: the sky, four stops brighter than the hillside and trees, or the minor variations in the foreground rocks. If I were to believe your viewpoint the camera should have focused on the trees.

If in single point mode the camera ignores the selected subject and focuses on what's most convenient for it - that would be an even worse flaw. This is exactly why there are "selectable" focus points.

Also, it seems to me you must notuse your camera much it real life situations. The images I've taken and shown here are very typical conditions and the 1D has more than enough ability to handle these - they are NORMAL contrast situations. Even the D60, with much less ability handles these conditions just fine. They have both done well in conditions I can't even see well enough to get an optimal focus manually.


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Old Mar 13, 2005, 9:03 PM   #17
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TDM_Canon_User

You're also missing my point - The D60 can focus well doesn't mean the 1D can do the same!!!

1. Taken as a whole the 45-point AF is probably better overall, but when you select one AF point out of 45, this tiny element is now smaller than the center cross element of the D60...
2. Now if this single tiny element aligned with an area which is totally black with no clear delimiter, how is it going to AF ???
3. The single center AF point of the D60 covers a much larger area -> one of its segment is bound to hit an area of high contrast where the camera can work with
4. The sub mirror on the 1D is curved elliptically so it can 'correct' for some amount of play on the main mirror: http://www.canon.com/technology/detail/35mm/af45/


5. Your camera is fine - send it in to Canon to check, but my guess is there's nothing wrong with this fine instrument.
-> If the single AF element on the flying eagle illustration below hit an area which is entirely white or black for example (instead of where it's aimed) the camera can't focus either - but a D60 with a larger AF element will overlap some contrasty details in this image (analogous to multiple 45-points link together), since each of its AF sensor is larger and might work where the 1D won't with one smaller element!!! http://www.naturescapes.net/032005/am0305.htm
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Old Mar 13, 2005, 11:29 PM   #18
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Actually it does. The sensor in the D60 is much smaller (lower resolution) than the focus sensor in the 1D. Also, the compute power behind the 1D focus is much better - with algorithms many years newer. In any case, the number of pixels dedicated to focusing in the 1D is much greater than what the D60 has. To quote that excellent article/link you pointed me to (thanks!):

Quote:
From Canon: This [45 point] sensor has 30 to 40 times more pixels than conventional AF line sensors [in the D60], and it can perform processes impossible for previous sensors, such as the quick and accurate writing of images at a certain level for all 45 points.
Anyway, I think you are under-estimating the ability of the Canon 45 point system. In all cases I think the 1D outperforms the D60... that is, when the mirror doesn't stick at the wrong spot. I think we are in total agreement about Canon being good stuff. But even Canon can have problematic designs - and can make "cheap" goods. The 1D Mark II is an excellent camera - I've many good images from it. On the other hand, something is acting up and it isn't as reliable as it once was. And yes, I am in contact with Canon and they are aware of the issue and want to see my camera again - this time with the raw images on CD so they can read what exactly is happening within the camera to make the images blurry (yes, they do think they are blurry and that the blur is not caused by operator error).

Also, I think the mirror is concave to focus the image onto a smaller area. Much like a reflector telescope has a concave (parabolic) surface as part of the optical path.

Hey - I appreciate the help you are offering - just remember you're not the only one who knows how these things work (something I sometimes forget).

Cheers,

Tim :bye:



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Old Mar 14, 2005, 5:09 AM   #19
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TDM_Canon_User wrote:
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Actually it does. The sensor in the D60 is much smaller (lower resolution) than the focus sensor in the 1D. Also, the compute power behind the 1D focus is much better - with algorithms many years newer. In any case, the number of pixels dedicated to focusing in the 1D is much greater than what the D60 has. To quote that excellent article/link you pointed me to (thanks!)
You still don't get it ???
It has nothing to do with resolution!!!

I'm talking about the AF size ie the area which the single AF cover, and not its resolution -> Many tiny AF sensors in the 1D can fit in the center AF area of the D60

Draw a square 1mm x 1mm area for the 1D as an example, and now draw a cross 3mm high x 2mm wide represented by the D60 coverage area - Does this larger area encompasses more detail to focus on than the smaller single sensor of the larger 45-points? If you point a 1mm x 1mm sensors at a 2mm x 2mm area with no detail to focus on - How can one expect a super high resolution sensor to focus? :shock:
A larger sensor (with less resolution) will see more defined edges outside the 1mm x 1mm limit because its area is larger, and will have more data to work with - Your picture with the building and antenna show that :G

Not trying to be a Smartalex here, but just trying to help - I never said the 45-point AF is inferior, in fact I'm all for it and you were the one who keep saying the D60 focuses better - I'm just trying to understand why in theses circumstances the D60 work out better that's all...

Here's an illustration of what I tried to convey red square is single AF in 1D vs yellow single AF for D60 (I don't know your crop so scaling is off) - but you should get my drift:
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Old Mar 14, 2005, 11:22 AM   #20
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BTW on the 10D, the active AF sensor areas are so much larger than the icon lit up in the viewfinder that it created problems for their users:





ie areas of high contrast outside the square AF icons in the viewfinder get focus instead by the overlapping elements creating all kind of front/back focus issues....
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