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Old Jan 30, 2004, 5:41 AM   #1
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Default Another focusing problem...!

Hi guys

On Tuesday i spent the day with my nearly 1 year old daughter (how sweet)....! After getting bored of watching daytime television I took out my 300D with 50mm f1.8 and starting taking shots. I took 59 shots in total varying speeds and aperatures (but most at about f4.5). The scene was well lit with no need for flash or very wide aperatures. Last night i downloaded all my images to my Mac but was amazed to find that only about 5 where pin sharp like one would expect from the 50mm lens. Before you ask, yes my daughter is a fast mover but not that fast. I always focus on the eyes yet a lot of these images where very blurred except in front of the eyes things (like toys) would be sharp.

I decided to experiment last night by shooting a scale ruler with a marked line on it and the results where frighteningly bad. Using the centre focus point in p/av/m mode all shots where off. All where sharper to the front of (closer to me) what i aimed the central focus point at. Does this mean i have a front focusing camera...? I have tried it with the 18 - 55 lens as well and yes it occurs there too. Its something I had always noticed but played it down to being the user and not the camera as i was learning. I will post pictures below:

http://www.pbase.com/richiehatch/bad_focus_300d

I think you can see what i mean if you view at 100%. Do you think i should return this camera or is there a solution...?

Thanks

Richie
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Old Jan 30, 2004, 8:44 AM   #2
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Default Looks like camera shake

Based on what I saw in the Exif for those pics, it looks like camera shake is your culprit (I assume you took those shots handheld). A good rule of thumb to follow is to not go below 1/focal length for your shutter speed. Try shooting at ~1/60 or higher at f/2.8. That should make a difference for you.
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Old Jan 30, 2004, 8:51 AM   #3
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Richie

Put the camera on tripod...

select the aperture prioroty mode, use F/8 or F11or f/16 to cover the focus range on both front and rear (DOF)of the ruler.
chose your point of focus, focus and shoot...to avoid camera motion, use timer function..

check result...see if you have the focus problem...stop litsenning to all of the bs paranoia whinnings...

Cheers
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Old Jan 30, 2004, 9:20 AM   #4
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One other comment regarding focus: Adjust your camera so that it is set to focus on only one focus point rather than the 7 that it defaults to if you haven't already done that. With the 7 focus points active, the camera will often choose the wrong point and unless you're paying strict attention to that, you may well think you're focusing on one point while the camera focuses on another.

And, don't confuse this back/front focus chatter with depth of field as I've seen others do.

I agree whole-heartedly with the other posters that at the shutter speeds and aperture you chose are not the best choices for testing. Camera shake at 1/20 sec is common and may even occur on anything other than a tripod with good support.
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Old Jan 30, 2004, 10:06 AM   #5
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Ritchie, This is exactly what I saw when I did the ruler test. The entire field of focus was well in fornt of the the subject. I shot at f 4, 1/60th with a flash so camera shake was not an issue. Your ruler is in focus closer in which would seem to rule out camera shake. Still, I'd be interested to see your results with a tripod.

I like the silly suggestion to use a tripod and set your aperature to f 16. That is an obvious attempt to increse the depth of field so that the entire ruler is in focus and doesn't prove anything if you are tryiing to test how well your camera focuses. Also, try setting AV to f16 and using a flash. It didn't work so well when I briefly owned a DRebel. The Drebel set a slow shutter speed despite the fact that I had the flash on. Or you could try taking a picture of your moving daughter with a tripod and the timer. Good luck with that!

Bill
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Old Jan 30, 2004, 10:29 AM   #6
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thanks guys....

yes i know the rule of thumb about lens length etc etc.... yes i know using a tripod would help (as it happens i had the camera proped on a back of my chair....!).yes i know that setting a smaller aperature would increase depth of field but that isnt the effect i want. Anyway camera shake would effect the entire image not just the part i focus locked onto. If definately does not explain how parts of the image closer to me are sharper than the point at which i focused on...! As well as that all of the shots i took of my daughter where handheld and at a speeds all above 125th at f4 or higher and where still out of focus even tough i locked to her eyes and she didnt move. I will post some images over at pbase on Monday (i am at work now and havent got them with me) and meanwhile i will do the ruler test on a tripod with flash to completely eliminate the camera shake option....!

Thanks guys

richie
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Old Jan 30, 2004, 11:10 AM   #7
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Quote:
Also, try setting AV to f16 and using a flash. It didn't work so well when I briefly owned a DRebel. The Drebel set a slow shutter speed despite the fact that I had the flash on.

No, it worked exactly how you told it to work. If you set the Av to f/16 in Av mode, the camera will select the corresponding shutter speed based on existing light conditions. The flash will then act as fill flash, not the main light. This is the normal behavior as explained in the manual.

If you want to control both the aperature setting AND the shutter speed, you must place the camera in M.


Richie, if you indeed feel that your camera does not focus properly, document your results and send it in to Canon for repair. I won't presume to know your level of knowledge and skill, so disregard this comment if it doesn't apply.... the majority of out of focus issues, underexposure flash issues, etc are the result of not understanding how your camera works and/or poor techniques. This may not be your case and there have been some cameras that needed to be adjusted by Canon.
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Old Jan 30, 2004, 12:11 PM   #8
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thanks ohenry.... its going to get a proper testing at the weekend as its my daughters 1st birthday on Sunday....! I think i will keep the aperature between f8 and 16 (if i can) to somewhat improve the sharpness...! Hopefully its not too dull (as it normally is here in Ireland).

Talk to you Monday

Richie
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Old Jan 30, 2004, 3:57 PM   #9
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ohenry, Are you seriously suggesting that people don't set the f stop wider than f/16? I'm glad I returned the camera if that is the only way to get a decent focus!

By the way, using aperture priority was not my suggestion. I was just commenting on somone else's suggestion.

Willie
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Old Jan 30, 2004, 6:56 PM   #10
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Quote:
Originally Posted by unclewillie
ohenry, Are you seriously suggesting that people don't set the f stop wider than f/16? I'm glad I returned the camera if that is the only way to get a decent focus!

By the way, using aperture priority was not my suggestion. I was just commenting on somone else's suggestion.

Willie
Apparently you didn't read my message correctly. I didn't suggest anything even remotely along that line.
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