Please help me Focus Clearly

[bouwy]

Help Please.


I just started photography and I do not know how to use the focus system correctly on my EOS 7D & EFS 17-55mm f2.8 IS.


I tried every possible combination, MF, AF, One shot, A1 & A1 servo in M, AV, TV & P. Most shots seems to be very sharp in a part of the photo,while the other part seemed to be out of focus.


Some shots are brilliant (inclusive in AUTO setting and using flash), but most are unsatisfactory. I have also a EOS 450D and have the same problem.


Can anyone put me on the right track. Thanks

[Sinh Nhut Nguyen]

Do you manually select the AF points or do you let the camera selects them for you? I only use the center point to focus and then I recompose. If you let the camera choose the focus point, it will focus on something that you do not want, usually something infront of your main subject. It's time to get the manual of the cameras you have out and figure out how to set your camera to use the center focus point.

[wickerprints]

I just want to make sure we eliminate this possibility, but are you aware of the concepts of selective focus and depth of field? Do you understand how f-number, subject distance, and focal length influence depth of field?

[bouwy]

I manually select the AF points and yes I use the center point to focus and yes I recompose, however when I take a shot of a 5 people standing next to each other and have selected all the right focus points and settings, I still find that the outer left and right are blurry. Yes your suggestion re: good read of the manual is warrant (which I have done over and over again, but will look at it again), I was hoping that anyone was going to tell me what I did right or wrong. Thanks anyway & I appreciate your input.

[bouwy]

Yes I do understand this. Thanks anyway

[Sinh Nhut Nguyen]

send me a full size sample image @ nhuto@hotmail.com ("nhuto@hotmail.com)

[Chuck Lee]

Your suffering from DSLR DOF reality. Did you shoot that group portrait at f8 or higher. My guess is you didn't. If you did, your shutter speed wasn't any better than 1/50th. That would suck. SLRs have a very shallow depth of field at apertures of f8 and less. Point and shoot compact cameras have much smaller sensors andmuch closer lens to focal plane distance. They obtain a much better depth of thing in focus than large format DSLRs. The trick is to know how to manipulate it. The general rule is to focus on what's up front and the rest will take care of it's self. Or in a group portrait, focus on the subject in-between and pray like hell you get the closests and the farthest in acceptable focus. When in doubt, print a 5 x7. You'll be suprised how sharp everything is. And use a good sharpening algorithim. Irfanview does a really good job. Try 75%. or reduce to 800 wide at 25%. Post processing is very important.


Excuse me if I'm being to bold here.........

[bouwy]

Thanks for your reply Chuck. Yes I often take shots less than f8, but shots taken at f8 or higher are not that great either. Still out of focus at the outer fringes of the pic. Yes I do use Irfanview. Great program. I'm now reading the manual for the 100th time (only joking, feels like it) and hope fully I will figure it out. Again Thanks.

[Sinh Nhut Nguyen]

thanks for the sample image, I've taken a look at it and concluded that there was nothing wrong with the focus, can you point out where you think the flaw is?

[bouwy]

thanks for the sample image, I've taken a look at it and concluded that there was nothing wrong with the focus, can you point out where you think the flaw is?
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Thanks Sinh for your time in accessing the image. The figures on the far outside on the image are not as clear as centre figures of the image. Am I to critical ?.

[Sinh Nhut Nguyen]

Yes you are too critical! I do notice a decrease in sharpnessin the corner of the image, but very minimal though, I have to look very carefully to notice that. Now, you need to know that lenses are sharper in the center than in the far corner. Great prime lenses are sharp from corner to corner, great zoom lenses are sharper in the center with a small decrease in sharpness in the corners, cheap consumer lenses tend to have very soft corners and ultra wide angle lenses tend to have very soft corner too. This is the concensul.If you read Bryan's reviews you will notice that he evaluates a lens performance both in the center and the corner, that's why when you take a look at the ISO 12233 crops you will see the crops in the center, mid frame and corner.


You lens is fine, your camera is fine, your focus is also fine. Stop pixel peeping, get over it, go ou there and start shooting! [:)][:)]


BTW, take a look at Bryan's ISO 12233 crops for the EF-S 17-55mm f/2.8 IS USM.


Nate,

[bouwy]

Yes you are too critical! I do notice a decrease in sharpnessin the corner of the image, but very minimal though, I have to look very carefully to notice that. Now, you need to know that lenses are sharper in the center than in the far corner. Great prime lenses are sharp from corner to corner, great zoom lenses are sharper in the center with a small decrease in sharpness in the corners, cheap consumer lenses tend to have very soft corners and ultra wide angle lenses tend to have very soft corner too. This is the concensul.If you read Bryan's reviews you will notice that he evaluates a lens performance both in the center and the corner, that's why when you take a look at the ISO 12233 crops you will see the crops in the center, mid frame and corner.


You lens is fine, your camera is fine, your focus is also fine. Stop pixel peeping, get over it, go ou there and start shooting! /emoticons/emotion-1.gif/emoticons/emotion-1.gif


BTW, take a look at Bryan's ISO 12233 crops for the EF-S 17-55mm f/2.8 IS USM.


Nate,
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Thanks Nate