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20D w/ 24-70 USM 2.8, focus hit& miss?
Old 06-01-2005, 09:21 PM   #1 (permalink)
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I'm new in the Canon scene and I find myself having a hard time grasping how the 20D thinks in terms of focus.


With the same DOF/exposure, some images seem tact sharp and some soft. I have experimented with selective AF and have yet to find a winning combination.

Anyone else having the same trouble?

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Re: 20D w/ 24-70 USM 2.8, focus hit& miss?
Old 06-02-2005, 02:42 AM   #2 (permalink)
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Can you post some examples of what you are seeing. I use the Canon 20D with a variety of lens and I get tack sharp images. But you must pay attention to details. Also keep in mind that the center focus point is almost twice as effective as the other points, so you may want to use it exclusively (that is what I do). As with all digital cameras, you need to observe the standard rules for handholding of 1/focal lenght. So if shooting at 70mm, you would need to have a shutter speed faster than 1/70th otherwise you will almost always have some softening of the photo. When in doubt, use a tripod. You also need to be sure that you don't have a problem lens. Some lens will back or front focus and this can pose a problem. So be sure you've tested each lens to make sure the focus is really what you point the focus point at.
The other thing that many people overlook is that they will press the shutter button halfway to lock focus, then they'll recompose. This will usually mean that about half their shots will not be sharp where they though they focused. This is because when you recompose you are changing the distance in many cases between what you focused on and the new place the focus point will be pointing after recompose.
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Re: 20D w/ 24-70 USM 2.8, focus hit& miss?
Old 06-02-2005, 07:04 AM   #3 (permalink)
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Yep dittos to what RFS said... plus,... if you see the subject not looking sharp in your view finder, don't be afraid to hit that focus once again..

Also,... (this is extremely helpful)... I have all my cameras..(film and digital) set up so I can AF independently of the shutter release.. The shutter release simply releases the shutter, and locks the metering when pressed half way down.. and I use the button on the back that looks like an astric (sp?) ....(looks like the think on your keyboard when you hit Shift + 8 at the same time.. " * ").... and then you can focus with much much more control.. In fact,..the other day,..my and my friend Dan were out target shooting and I used his camera which isn't set up like mine..but rather to the default way,....well,...I had so much trouble shooting the "normal" way that I actually switched it to manual focus.. Oh, and,...how you set it us is by going into custome functions and select CF 4, with option No. 1 AE Lock / AF ....it takes a day or two to get used to but, once you do,...you'll be thanking me..

Now try that.. [img]/ubbthreads/images/graemlins/smile.gif[/img]

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Re: 20D w/ 24-70 USM 2.8, focus hit& miss?
Old 06-02-2005, 12:02 PM   #4 (permalink)
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I don't know if this would help or not, but I only learned fairly recently that not all focus points are created equal. For example, on my ancient D60 only the center focus point focuses very accurately. The other focus points have a wider tolerance for focus. So if I'm using a narrow DOF, I got to use the center point.

Seems like I read somewhere that the 20D is similar, only a few of the focus points are the more sensitive type.

Like I said, maybe this helps, maybe it doesn't.

lb
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Re: 20D w/ 24-70 USM 2.8, focus hit& miss?
Old 06-02-2005, 10:00 PM   #5 (permalink)
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I hope it's not a faulty lens.

I will concentrate on using the center focus point.

Thanks!

-Chris
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