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Old Jun 12, 2004, 1:23 AM   #1
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Anyone had this problem with the Rebel/300D.?

The Focus point in this image is at the bottom of the steps yet that area is totally out of focus and the top of the steps are really sharp. You are looking down the steps BTW.



Any ideas folks. Should I take the Camera back.?

Cheers

Mart.:sad:
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Old Jun 12, 2004, 3:21 AM   #2
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If you look at a raw image using the EosViewerUtility or some other tools, you can confirm the focus point -- if the sensor actually tried to use the distant point and got the close point instead, then you should sendthe camera & lensback for an adjustment.

A test shot with a wide aperture and a ruler using a tripod can make this even more clear if necessary.

The following link is another one of this sort.

http://www.photo.net/bboard/q-and-a-...?msg_id=008MTa
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Old Jun 12, 2004, 6:41 AM   #3
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Hi MadWand

Thanks for your answer.

I have checked the focus point using the EOS File viewer, and it is where I said yet as you see from the picture it's totally out of focus.

The problem is that you cannot trust the camera to give a good focus, through the viewfinder looks great then the actual picture looks bad.

I'll take it back I think and ask to try another one, only had it one week. When the shots are sharp they are really sharp. It seems more prominent at telephoto lengths rather than close up shots. Looks like it's quite common reading those other threads.

Thanks again.

Mart.:sad:

PS. I've read some of the other threads and some suggest the softness is normal, the problem I'm having is not softness but incorrect focus point. When the pictures sharp it really is sharp, so soft focus is nothing to do with it.

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Old Jun 12, 2004, 6:58 AM   #4
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Just wondering . . . is this an intermittent problem or is it consistent?

David
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Old Jun 12, 2004, 7:14 AM   #5
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Hi David

It's hard to say cus I seem to have had some good shots but most distant shots focus in the wrong place or don't seem to focus at all.

I'm gonna try some more tests using the suggested ruler or tape and a few objects lined up. I'll use both the Kit lense and my sigma zoom cus it seems to happen with both of the lenses.

I'll post some results as soon as I've done the tests.

cheers



Mart.
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Old Jun 12, 2004, 7:22 AM   #6
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Another consideration is the actual AF area is much larger than the rectangular ouline shown in the camera viewfinder... For illustration only I have attached this modified picture, but clearly the wrong area is selected.

Also certain AF area are sensitive to horizontal details, while other are sensitive to vertical, so be careful when you rotate the camera. Only the center AF point is sensitive to both, but even so the camera can focus outside the focus indicator because its AF active area is larger than what is indicated in the viewfinder!

BTW I'm also in the opinion of people on the posted threads that the issue is rarely the lens, but the camera itself: The focusing element is in the camera, the smartness(software) is also in the camera. The lens is just commanded by the camera to focus back and forth until focus is achieved and detected by the AF sensors on the camera (think about when a teleconverter is inserted between the lens and the camera as well)!
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Old Jun 12, 2004, 8:18 AM   #7
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NHL

I should have said but the image you are using is a 100% crop from the original and is in the normal orientation not rotated and the focus point the camera selected was the center one. So the problem is for real I think but the tests I'm going to do should prove it. I hope.

BTW, where did you get the info about the focus area for each focus point, very useful info. It's not in the manual is it.?:?

Cheers

Mart.


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Old Jun 12, 2004, 9:14 AM   #8
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Don't know if this has to do with what your problem is or not, but . . . .

One day I am out taking some various pix & shooting a passing train. I want to get a pix of the crewman from another stopped train with the rail cars passing in the background (I am using the 28-135 IS) & the lens keeps on focusing NOT on him, but the moving freight cars, so I have to switch the lens over to Manual in order to get the shot I want. I also had this problem at an outdoor music event - before I tried the switching over to Manual - now I know. Autofocus can be a pain sometimes - I remember having this problem back in the 1980's with my S-VHS camcorder, & I put it in Manual focus & left it there!
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Old Jun 12, 2004, 9:52 AM   #9
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Hi Railfire

Once I've done me tests I'll be pretty sure of what's going on, you might be right about it hunting for the wrong thing but I can't see how it's got anything else to find on these steps. The focus was clear through the viewfinder at the bottom of the steps and the pic speaks for itself.

I'll be doing the test tomorrow if the weather's good, I've setup some numbered boards which I'm going to lay out at two yard intervals, there's five in all. I'll be focusing on the number 3 board and see which ones come out in true focus. If that fails I'll try focusing on a different number and test again.

cheers

Mart.
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Old Jun 12, 2004, 8:59 PM   #10
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mf_blues wrote:
Quote:
... BTW, where did you get the info about the focus area for each focus point, very useful info. It's not in the manual is it.?:?
Everything is here (10D focus issue demystified): http://photography-on-the.net/forum/...?TopicID=10948

"In all cases, the actual area that can potentially be evaluated by the AF system is larger than indicated by the AF frame engraved on the focusing screen."
http://www.pbase.com/image/18920257
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