Is my Canon 17-55 2.8 IS lens front focussing?

dubcat

dubcat

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Amir
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Hi - I'm not really clued up enough to know what front focussing really means but i suspect i am suffering from it.

I checked my camera and the focus point was the mouth - the right side of it. As you can see in the pic the face is soft but the rug just in front of her is pin sharp! Is this what people mean by front focussing?

I'm gutted because I've noticed many of my wide open shots are slightly out of focus and always thought it was my own lack of skill.. However now i think it is an issue with the camera or the lens. I have had them for a year now though so i can't exactly take them back as faulty :(

I read there is a micro focus capability in my camera - the 50d. Would this help or is the lens too 'out'?

Love to hear your thoughts.
Dub

50d body, 17-55mm f/2.8 IS lens at IS800, f/2.8 and 42mm:
IMG_1831.jpg
 
9 times out of 10 it's user error. I've plenty of shots like this and I'm sure my lenses are fine. Shoot a static subject while on a tripod (IS off), making sure focus locks and see how it performs. Chances are the child was moving, perhaps you accidentally moved too, maybe you missed your mark with the focus point, maybe the light was low and focus lock didn't actually occur... Plenty of things it could be besides your lens.
 
Hmm ok. Good points. I'll conduct some more scientific tests.
 
Best thing to do is get some decent light indoors and shoot an inanimate object using LiveView and a tripod and use either a remote shutter or the self timer. You can test various apertures at various focal lengths to see how it performs on auto focus. If you can manage to get a sharper image using manual focus on LiveView, your camera and/or lens needs calibrating.

This is probably not the case, however. I did this test and found that my 17-85mm is stupidly soft at the wide end compared to the macro end, to the point where it's not even funny, but the focus was spot on.
 
im only new but i tested my lens's the other day, what i done was stuck a cane in the ground, focused in at the base of it and took some pictures on different settings,

then use the grass around the cane to judge where the focusing was at its sharpest.
(it was sharpest at the cane)
made it real easy for me and the lens werent off at all..

not technical i know, but it worked for me.. :D
 
Go and buy a cheap steel tape measure.

Lie the tape measure on your kitchen floor and weight it down.

Get a peice if white paper and draw a fine line on it, stick it under a mark on the measure say at 2m.

Put your camera on a tripod and shoot the tape low down focusing on the paper with the line.

Put the CF card in your computer and look at the photo. You should have a picture of a tape measure that when blown up will have a point where it's in focus.

Is the tape in focus in front ot behind the line ?

Try the lens at different apertures, it will be different.

Now try adjusting the camera for Front ot Back focus and retake the pictures.

The best distance to test the lens at can be found here.

http://www.lensalign.com/ldt/index.html

This site will also show you the pro kit to test with, but be aware the prices arent cheap :D
 
At such wide apertures I find that merely the beating of my heart can throw me off. I doubt the equipment is at fault.
 
From what you guys have written my focus and recompose is probably the guilty party. Am I better off using ai servo mode?
 
Focus and recompose almost always buggers me up at apertures narrower than f/2.8 so yes, I'd consider re-evaluating your technique.
 
The canon tutorial on autofocus on B&H photo video (go to site and tutorials and type Canon autofocus in search) helped me no end with this.
 
I'm afraid that's just user error. Focus is too far out for it to be a calibration issue.

Focus-recompose is tricky at close distance and low f/numbers. You don't say what shutter speed but there is subject movement evident too.

Checking the focus point only tells you which point was used, not necessarily what was focused on when the picture was taken.
 
Dan1502 said:
The canon tutorial on autofocus on B&H photo video (go to site and tutorials and type Canon autofocus in search) helped me no end with this.
Click to expand...

Hi

Do you have a link? I searched but could not find it.

Cheers

Dub
 
HoppyUK said:
I'm afraid that's just user error. Focus is too far out for it to be a calibration issue.

Focus-recompose is tricky at close distance and low f/numbers. You don't say what shutter speed but there is subject movement evident too.

Checking the focus point only tells you which point was used, not necessarily what was focused on when the picture was taken.
Click to expand...

Thanks Hoppy. I am pleased to hear that. User error is far easier for me to cure.
 
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