help! canon 17-55 2.8 lens...

shaylou

shaylou

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Shayne
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I'm a newbe that needs your help. Using canon T3i and just bought a 17-55 2.8 lens.
My other two lenses, 50mm 1.8, let lens 18-55 are no problem using but my 17-55 is nothing but problems. Almost all of my pics are out of focus. I had the lens looked at by two different shops and got two entirely different conclusions. The first shop said the lens was fine but I should expect that at 2.8 it won't perform as well as if it is stopped down. The second shop didn't call me like they were suppose to, could find my work order and then basically hung up on me (said in a panic) "we will call you back". Once they called me back they said they needed to replace the motor along with everything else (basically) and it was going to cost ..... needless to say, I dont feel good about that diagnoses. My question is what are the basics that I need to set my camera to in order to eliminate user error. I can set it up in any surroundings (light, focal distance) that you instruct me. Sorry if this post is a bit out there, I'm just frustrated at this point. Thank you very much for your help.

Btw, I went to a local forum here in the u.s. (Houston Texas) and posted a few questions. The response was a let down compared to this forum. The members of this forum rock! Thanks again....
 
I understand your frustration, there's a lot of words there and virtually no useful information.

What do you believe is wrong with the lens?

Could you post a picture with examples?

What testing have you done?

There are lots of sites on the web with instructions for testing lenses, and you're very lucky, because you have 3 lenses that'll shoot at 50mm. You can take the same shot exactly with all 3 lenses for comparison.
 
Sorry about that. As you can see my frustration has got the best of me. One of the reasons I went with this lens is because of the low light capabilities. My problem is that when using wide open I get out of focus shots. It seems that I don't get focused shots until I'm around f3.8 or so. I tried to cut to the chase and take it straight to the "pros" to to have it checked out but that left me with more questions than answers. I looked up test but as a beginner I'm a bit intimidated with their suggestions. I think I would end up questioning the actual test I performed. I was hoping that there are some simple test or even better some tips on settings I should use or stay away from. I should point out that I did not experience this with either of my other lenses. That's not to say that it is not user error because that is highly likely.
Thanks for your help Phil.
Btw, the advise you gave me on understanding your cameras limitations was priceless. That should be on a wall somewhere.
 
The lens should be great - that's why you bought it right, obviously like any lens it improves when stopped down. But it should be sharper at 2.8 than your kit lens wide open.

The most likely candidate is mis-focus, shallow DoF shows up faults in focussing technique - which is why I suggested a proper test - nothing to be scared of, just set up a tripod and a static subject. If you don't have a tripod - use bright daylight, good technique and a high shutter speed.

If that shows mis-focus then you'll have to do a proper test to ascertain how 'out' it is - or return it.

If it's soft rather than misfocussing, again return it - the lens should be sharp.

If you look on my website, most of the obvious standard lens shots will have been shot with that lens, and I have no worries about shooting wide open -no point in buying a fast lens if you're going to shoot everything at f8.

Glad I've been of help, sometimes the internet feels like we're just shouting out into space and no-one takes any notice.
 
Hi I had the same problem with my 17-55. Did a quick AF test using tape rule at 45 degrees to the lens at about 5ft away. I found the lens body combination was front focusing. Fortunatly on the 7D you can adjust this out. By using micro adgust. Unfortunatly I dont think the 3Ti has this adjustment. So would need to be done by Canon. If you need more info on doing test happy to help.
 
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Front focusing is to be expected if you use an angled rule as the target at which you aim. You want your target to be parallel with the sensor plane. By all means use an angled rule alongside the target in order to identify where the sharp point lies, but focusing on an angled target is not the way to do things.

Something like this is ideal....

Setup :
20100219_122041_0119_LR.jpg


Result :
20100220_161721_0120_LR.jpg


Otherwise, if you compare the size of the focus squares to the details on the ruler you see that a single point covers a whole range of distance values. What's worse, the sensitivity of the AF point extends further than the marked AF point size in all directions. How can you possibly know where the camera should have focused? It could be anywhere within a range of a few cm.

Of course you can spend quite a bit on a ready made tool, with essentially the same design intentions....

http://michaeltapesdesign.com/lensalign.html

But take note of the principles involved. The angled rule is not the focus target. It is used as a separate scale from which to read the sharpest point of focus relative to your non angled target.
 
Hi hope this helps. Pick a series of lines (news print, railings) Focus on one of them pick one you can remember. Download and check were the infocus line is. If it is infront of your chosen line the canera/lens is front focus ing. If behind its back focusing. Make sure you use a tripod and F2.8. If you need more info ask again
 
Hi no the rule is the target. But you have to set it so that it fills asmuch of the frame as possible at 55mm. Stop down to f2.8. Use the lines on the rule as markers only.
 
this lens is sharp from f2.8. I tend not to shoot charts etc as I used to get into all sorts of bother. There is obviously a problem with it as two shops couldn't get a sharp shot at f2.8. Contact http://www.hlehmann.co.uk/ and they'll sort you out I should think.
 
walls said:
this lens is sharp from f2.8. I tend not to shoot charts etc as I used to get into all sorts of bother. There is obviously a problem with it as two shops couldn't get a sharp shot at f2.8. Contact http://www.hlehmann.co.uk/ and they'll sort you out I should think.
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I picked it up from the second shop today, the one that I think is full of it. When I ask him how he came to the conclusion his response was "we have been doing this for 40 years". A bit defense wouldn't you say. I ask him what kind of camera he tested it with and he said they didn't, and that he just took the mounting cover off and looked at it. Point is, one shop said it was fine and the other was unreliable at best.
 
Well it seems as if this comes down to user error (I think). I did what you said and went out in bright sunshine, set up a small display and opened the lens wide open. When I let the camera decide what to focus on it got it wrong most of the time and I ended up with out of focus pics. When I set it to spot metering it was as sharp as I could ever hope for (I'm so happy). I'm not 100% sure if this is normal or if there is something else I'm missing in my setup. Thought?
 
I think you are confusing your terms a little. Spot metering is about the exposure, not the focus. I think what you mean to say is that switching to a single AF point instead of all AF points (Automatic Focus Point Selection) has put you in control of where the camera focuses and the result are now what you were hoping for.

With AFPS in One Shot AF mode the camera will focus on the nearest thing covered by a focus point that has sufficient contrast to occur. So the camera might focus on a table instead of a person seated at it, or a twig instead of a mountain, or a hand instead of a face. AFPS has its uses, but most of the time you are probably better off picking a single AF point that is closest in the frame to the thing you want sharp. Then focus and recompose if need be.

When you use AFPS in AI Servo mode the behaviour is a bit different. You need to first lock onto the subject with the centre AF point. Then if the subject moves within the frame the camera will attempt to stay locked on. A common user error is to assume that so long as an AF point os on the subject that's good enough. It isn't. You must let the camera know where the subject is by commencing tracking with the centre point first of all.

These two behaviours can be confusing until you get used to the way things work. Of course, if you only use one AF point then the confusion disappears.
 
Could you repeat that in English please.. haha, yep your correct it's confusing to me. I read a lot of post where you guys are using those terms and I have a hard time keeping up. I obviously need to learn this so I can concentrate on the fun stuff. This is how confused I am, what do I Google to get some learning tools. Man you know you don't understand it when you don't even know what question to ask! Thanks a lot for your help this is one of those post I will definitely refer back to.
 
Hi Shaylou, I have just been reading this thread with interest as I am thinking of buying a 17-55 myself. No point in me adding anything regards to testing this as it will probably confuse you even more. Just a thought though, if you can tell people where you are based there might be a member on here that is local and could meet up with you for an hour to do a test on the lens as well as explain things in the process, like I say just a thought.
 
u8myufo said:
.....if you can tell people where you are based there might be a member on here that is local and could meet up with you for an hour to do a test on the lens as well as explain things in the process, like I say just a thought.
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He's in Houston, Texas! :D
 
shaylou said:
Could you repeat that in English please.. haha, yep your correct it's confusing to me. I read a lot of post where you guys are using those terms and I have a hard time keeping up. I obviously need to learn this so I can concentrate on the fun stuff. This is how confused I am, what do I Google to get some learning tools. Man you know you don't understand it when you don't even know what question to ask! Thanks a lot for your help this is one of those post I will definitely refer back to.
Click to expand...

OK, I'll have another go. Your camera has several AF points (not sure how many on your model). Either the camera can pick which one to use or you can. If you let the camera pick then it might get it wrong. It can't know. Only you can. If you want dependable results then make sure you are the one selecting the active focus point, not the camera.

A lot of people will only ever use the centre AF point. It keeps things very simple and usually very accurate. If they need to focus and then recompose then mostly that will work very well. That technique can fall apart when shooting at very wide apertures within close range of your subject, but mostly it works well enough. You can't focus/recompose on subjects which are moving towards you or away from you.

I assume you have three AF modes on your camera - One Shot, AI Focus and AI Servo.....

One Shot is the best choice for subjects which are not moving - a seated person, a building, a landscape, bowl of fruit etc..
AI Servo is best used for moving subject such as cars, planes, joggers, running dogs and so on.
AI Focus is best avoided. It is supposed to switch modes from One Shot to AI Servo and back depending on what it thinks is happening with your subject/scene. Sometimes it gets it right. Sometimes it screws up. It really is a mode that can trip you up. Even Canon will caution against its use. The professional camera do not have this mode at all. There is a good reason for that.



The puzzle for me is why your issues have only materialised with the 17-55. Surely if the 17-55 was bad the 50/1.8 would have been even worse. You did buy it for the fast aperture I presume. :thinking:
 
Stick the camera on a tripod, IS off and take a few photos at f/2.8 with the centre AF point on one shot then see how sharp they are. Best use the in camera tiimer if you don't have a remote shutter release to minimise any movement

If its as knackered as one shop said it will be very noticeably out of focus, you need to know if its equipment or user error before you go any further
 
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The puzzle for me is why your issues have only materialised with the 17-55. Surely if the 17-55 was bad the 50/1.8 would have been even worse. You did buy it for the fast aperture I presume. :thinking:[/QUOTE]

Exactly! that's why I was so concerned about the lens I bought. It was second hand and I never experienced this problem before.
 
Some very good suggestions, but why don't you just send it to Canon and ask them to check it, if you don't feel confident about doing this? They'll either confirm that it's 100%, which means it's user error, or they'll sort it out.
 
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