AF point put of focus! How come?


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dogbone

New Member
Sep 28, 2008
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#1
Hi everyone,

I am a newbie and i just bought my 450D kit 2 weeks ago.

I cant help but notice that the some of the AF points in the viewfinder (bottom 3 AF points to be specific) seem to be out of focus while the other points looks very sharp in comparison. I tried adjusting the knob near the viewfinder (to focus all the points) but it doesnt work, as the same 3 points are still out of focus.

I brought the camera back to CP (where i bought the camera) to ask them to check. The salesman noted the same problem but he says its not a fault cause if we look long enough the 3 points will start to focus (thats what he says but i don see any change). To convince me further, he showed me another 450D which has exactly the same problem. Then showed me a 50D, this time round the out of focus AF point is the top one.

So he just told me that this might be a manufacturing fault by CANON, and ask me to send to service center to check if this problem is registered.

Hence i am just wondering if this problem is common in all 450D and if any one is experiencing this problem?

This i a rather small problem but it is very disturbing when i take pics. Should i head down to
CSC to check? or simply ignore it?

Thanks for your help in advance!
 

Last edited:

ombre

Senior Member
Sep 3, 2008
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#2
Well, I'm not sure if its common to all 450D, maybe the lens is front/back focused too, or the lens has a bad "bottom", so to speak. All these errors will not be handled by the shop, they'll push you to Canon Service Centre once you leave their shop... which is technically the 'black and white' thing to do.

Since its under warranty, bring it to the service center and have it reconfigured. Puts your mind at piece too.
 

dogbone

New Member
Sep 28, 2008
26
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#3
Well, I'm not sure if its common to all 450D, maybe the lens is front/back focused too, or the lens has a bad "bottom", so to speak. All these errors will not be handled by the shop, they'll push you to Canon Service Centre once you leave their shop... which is technically the 'black and white' thing to do.

Since its under warranty, bring it to the service center and have it reconfigured. Puts your mind at piece too.
Hmmm.. what do u mean when u say lens is front/back focused? How do we detect that?
 

wdEvA

Senior Member
Sep 1, 2006
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etanphotography.com
#4
when u say points out of focus, do you mean the points itself of the pictures it focus on?
If it's the points itself (the circles), it would be the focusing screen problem, (since u mentioned u already adjust the diopter, i think it's spelt that way)
you can try taking out the focusing screen of the 450D to check if the points are clearly on the screen. (not how to remove for 450D though), u might wan to google =x and do @ ur own risk, else can bring down to CSS and tell them to check
 

ombre

Senior Member
Sep 3, 2008
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#5
try this with each of your lenses.

Put your AF on the center point only, take a printed matter inclined at a about 45 or 60 degrees angle. Try to use a wide open aperture and the longest end of each lens.

Check and review if the center spot (do not reframe) is the sharpest focus. Sometimes we get biased focuses on the front or back of the center point, this is known as front/back focusing respectively. It can interfere with critical scenes with thin depth of field.

In your case, this may also be confused with out of focus. Your AF point may light up confirming focus, however, the lens is actually front or back focused, making your subject look out of focus.

I'm not sure if my explanation is clear enough, you can goggle for a better explanation. Have my hands abit full if not I actually have sample shots that I can share. But I think google will help you better.
 

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