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Old Aug 5, 2011, 9:10 PM   #1
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Default Need help with focus!!

Been looking around a few forums to post my question, and it seems this one is the one the seems the best!

Now, here is my problem :
I can't seem to ever get the focus spot on... always close, but never perfect. Tried everything I can think of : ISO, AF/MF, IS/OS on and off, different lenses. I've tried 3 lenses up to now, and nothing gives me perfect results.

Could the camera be "out of focus"? Really bad luck with 3 different lenses? Bad technique? Or am I just expecting too much out of the T1i?

I've included an attachment to show the best I've been able to do in the past week. I'll gladly sent the original pic if needed.
Attached Images
 
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Old Aug 5, 2011, 9:41 PM   #2
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The images exif data would be helpful.
Contains the aperture set, focal length used, shutter speed, ISO used, on newer canon lenses even the distance focused at.
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Old Aug 5, 2011, 10:23 PM   #3
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Quote:
Originally Posted by PeterP View Post
The images exif data would be helpful.
Contains the aperture set, focal length used, shutter speed, ISO used, on newer canon lenses even the distance focused at.
Yes, it could be useful!

Here it is in .txt format
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File Type: txt Focus exif.txt (8.7 KB, 138 views)
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Old Aug 6, 2011, 12:25 AM   #4
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select the af point
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Old Aug 6, 2011, 3:14 AM   #5
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Quote:
Originally Posted by Badguy75 View Post
Been looking around a few forums to post my question, and it seems this one is the one the seems the best!

Now, here is my problem :
I can't seem to ever get the focus spot on... always close, but never perfect. Tried everything I can think of : ISO, AF/MF, IS/OS on and off, different lenses. I've tried 3 lenses up to now, and nothing gives me perfect results.
Welcome to the forum.

Quote:
Could the camera be "out of focus"? Really bad luck with 3 different lenses? Bad technique? Or am I just expecting too much out of the T1i?
It seems unlikely that there is a problem with the camera. Even if
there was a problem with the autofocus system, manual focus should
work properly. If you have doubts about the camera, try shooting a
focus test chart. http://regex.info/blog/photo-tech/focus-chart

The default setting of the T1i uses all nine AF points. I find that
mine will focus on anything in the frame except for the subject.
I usually use single point AF using the centre AF point for shots
where focus is critical.

If you are using manual focus, make sure the diopter adjustment
in the viewfinder is set properly for your eyesight.

Quote:
I've included an attachment to show the best I've been able to do in the past week. I'll gladly sent the original pic if needed.
It would help if we could see the EXIF info. If you upload a large image,
the forum software automatically resizes it. During this process, the
EXIF info is removed from the image file. Make sure your photo is smaller
than 1024 pixels on the longest side before you upload it. See this post:
http://forums.steves-digicams.com/1187480-post11.html
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Old Aug 6, 2011, 6:56 AM   #6
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idenny has the right idea. select the center focus point then make sure it is on the object you want in focus. choose an fstop for whatever dof you want and there you got it
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Old Aug 6, 2011, 10:34 AM   #7
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Quote:
Originally Posted by Badguy75 View Post
Yes, it could be useful!

Here it is in .txt format
Thanks. That gives a clear picture of how you took the shot.

Your focus seems to be reasonably accurate. The sharpest
point is a couple of inches in front of the duck. The error (if any) is
quite small.

I see you took the shot at the widest aperture setting of f/5.6. This gives
a fairly shallow DOF as shown by the blurred background. I think you
could get a sharper image if you stop the lens down by 1 stop to f/8.
This will increase DOF a bit, but focus accuracy will be less critical.

I don't have any experience with this lens, but I have found that most
zoom lenses in this price range are a bit soft at maximum aperture.
Stopping down a bit will usually result in a sharper image.

Your shot was taken at: 1/500s f/5.6 ISO-400

In the same light, I would try 1/250s f/8 ISO-400

or maybe 1/125s f/8 ISO-200 using OS or on a
tripod with OS off.
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Old Aug 6, 2011, 5:50 PM   #8
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Quote:
Originally Posted by corkpix View Post
Thanks. That gives a clear picture of how you took the shot.

Your focus seems to be reasonably accurate. The sharpest
point is a couple of inches in front of the duck. The error (if any) is
quite small.

I see you took the shot at the widest aperture setting of f/5.6. This gives
a fairly shallow DOF as shown by the blurred background. I think you
could get a sharper image if you stop the lens down by 1 stop to f/8.
This will increase DOF a bit, but focus accuracy will be less critical.

I don't have any experience with this lens, but I have found that most
zoom lenses in this price range are a bit soft at maximum aperture.
Stopping down a bit will usually result in a sharper image.

Your shot was taken at: 1/500s f/5.6 ISO-400

In the same light, I would try 1/250s f/8 ISO-400

or maybe 1/125s f/8 ISO-200 using OS or on a
tripod with OS off.
Thanks for the information.

I've been using the center focus point ever since I learned how to use manual and A-Dep modes.

The focus in the eye-piece is perfect, everything seems crystal clear, and has been adjusted for my eye sight.

I have tried using higher ISO (200-400) and lower aperture, and no success with any of these.
I was out today taking some pics, and nothing seemed to work... 200 ISO, lower apertures, tripod mounted, no OS, manual focus, auto focus, OS on... Not one pic was crystal clear.

I've had that problem with all 3 lenses I have owned.
I might try another Sigma 120-400 lens that one of my friends has, and will try my 120-400 on his 60D.

I'll print out the focus test chart and snap up a few pics with different settings and post them on here.

Thanks,
David
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Old Aug 7, 2011, 12:10 AM   #9
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It does look slightly off perhaps, but possibly just at the limit of the factory tolerance.

You need to shoot some test charts. It is possible that your camera needs calibration.

You can send your camera and lenses to Canon and they will (though possibly they may charge a fee) calibrate your camera and lenses. Get in contact with your Canon service centre. This sort of thing is free if you have a subscription to their pro services.

Also it's not really obvious how you are judging what is "crystal clear". Hopefully not at 100% magnification on a computer screen. Almost nothing looks sharp at 100% even with the most expensive equipment.
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Old Aug 7, 2011, 8:48 PM   #10
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Just got around to testing the focus with some charts, and I seem to have a slight back focus problem with the camers.
I didn't have much light to test with, so I will redo the tests tommorow when there is more natural sunlight.
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File Type: txt IMG_4989 exif.txt (8.5 KB, 98 views)
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