Cameras forum

General discussion

Auto Focusing Problem

by xeng_her / April 15, 2010 7:50 AM PDT

I have a Canon 40D body and I'm using 18-55 IS LENS and there seems to be a problem with the auto focusing problem. How can I fix that? And how much will it cost me to fix it?

Post a reply
Discussion is locked
You are posting a reply to: Auto Focusing Problem
The posting of advertisements, profanity, or personal attacks is prohibited. Please refer to our CNET Forums policies for details. All submitted content is subject to our Terms of Use.
Track this discussion and email me when there are updates

If you're asking for technical help, please be sure to include all your system info, including operating system, model number, and any other specifics related to the problem. Also please exercise your best judgment when posting in the forums--revealing personal information such as your e-mail address, telephone number, and address is not recommended.

You are reporting the following post: Auto Focusing Problem
This post has been flagged and will be reviewed by our staff. Thank you for helping us maintain CNET's great community.
Sorry, there was a problem flagging this post. Please try again now or at a later time.
If you believe this post is offensive or violates the CNET Forums' Usage policies, you can report it below (this will not automatically remove the post). Once reported, our moderators will be notified and the post will be reviewed.
Collapse -
a few questions to help
by kalel33-20416052469708587370302374692233 / April 15, 2010 8:34 AM PDT
In reply to: Auto Focusing Problem

What focusing mode do you have it in?

Are you using all points active?

Are you having front/back focus problems?

Have you checked the Zoombrowser EX software, that came with the camera, to find out if the subject that is in focus is the selected focus point?

Is this camera new to you?

Do you have any problems with any other lenses?

Are you locking the focus and then recomposing?

If you don't know how to check the focus point selected then all you have to do is open EOS Viewer Utility. Double click on a thumbnail to enlarge image display. Along the top are icons. The "Show or Hide AF Point" icon is immediately to the right of the IPICT icon (has a little red retangle on it). Click on the "Show or Hide AF Point" icon and it will display the AF point used.

Collapse -
by kalel33-20416052469708587370302374692233 / April 15, 2010 9:06 AM PDT

From reading your previous questions, I have a good guess that you're new to DSLRs. Just a couple of more questions.

Have you read the manual from front to back?

Do you understand depth of field?

I'm guessing you're using the 40D in auto mode with all focus points active. People can't use a DSLR like a point and shoot camera. The camera doesn't know what subject that you are wanting in focus and usually chooses the closest point with contrast. Since DSLRs have a shallow depth of field then you can easily mess up the photo by having it focus on the wrong area and thus blaming the camera for the problem.

I see you are wanting to do portrait/glamour photography. I'd recommend learning the basics first(exposure, shutter speed, focal lengths, aperture, etc.). You can buy the most expensive equipment you want, but the most important part of making a good photograph is the person behind the camera, their knowledge, creativity, and skill.

Collapse -
by xeng_her / April 15, 2010 9:36 AM PDT
In reply to: Forgot

Yea, I am completely new to this. I haven't read the manual from front to back yet. I believe it's the lens. I'm not completely sure. I just bought the camera online because one of my buddies had one and I used it at his place and I really like it so i bought one.

Collapse -
few suggestions
by kalel33-20416052469708587370302374692233 / April 15, 2010 10:04 AM PDT
In reply to: help?

You're friends DSLR might have been set up for centerpoint only or he chose his focus points. If you shoot in the green box and haven't set up the AF then it's set to all points active, which is not very good for normal shooting.

If you still think it's the lens then change your AF(auto focus) to center point only and take some photos with one of your friend's lens. If his lens is fine on his camera then it should work just fine on yours. You can also test your 18-55IS lens the same way by doing the same thing, but making sure that the subject is in center when you compose the shot.

Since you're new then you really really need to read the manual. Even if someone has used a DSLR before they need to read the manual to understand the differences/updates to this new DSLR. On's forum there was a slew of people that had DSLR experience and had horrid problems with the Canon 7D not focusing properly. All of them were completely due to operator error and not reading the manual because the 7D has a much more sophisticated AF system that can be tailor set to many more possibilities than their 30D, 40D, or 50D.

I've also seen tons and tons of people new to DSLR who said their lens or camera wasn't focusing properly. Over 90% of them were due to not reading the manual, not understanding depth of field with DSLRs, not understanding the AF system of their Canon DSLR, and using it like a point and shoot. That's the reason I asked so many questions, which I'm still hoping your going to answer the first barrage of them.

With you being new to DSLRs you should expect that you are the problem and work from there first. There is a chance that the camera or lens has a problem but it's almost always the operator error, especially with people with little knowledge of the camera, photography, and who are new to DSLRs.

Collapse -
by xeng_her / April 15, 2010 10:09 AM PDT
In reply to: few suggestions

Thanks. I'm hoping that it's just me and not the product which is likely it is me. I also have another question. Whenever I switch lens, do I just put on or do I have to set up something for the other lens to work with my dSLR?

Collapse -
you don't have to do anything
by kalel33-20416052469708587370302374692233 / April 15, 2010 10:22 AM PDT
In reply to: thanks

Lenses can be changed between bodies. The reason I want you to try out his lens is to make sure the body isn't the problem or that the AF setting isn't the problem. You should make sure to set the AF system to center-point only and make sure the thing you want focused on is in that center AF point while looking through the viewfinder.

If the lens is a problem then it would not be off by much...were talking 2-6" off. If you're getting photos that show the focus is off by more than that then it's probably not the lens.

Lastly, did you look at your photos in the software I told you about and looked at the where the camera chose to focus? That might just end the speculation right there without having to do anything with the camera or lens. If you use the software to view the photo, choose to show the focus points chosen, and the thing that is in focus is right in/next to that focus point then you have found out the camera did it's job, just not what job you were expecting it to do.

Collapse -
focus problem
by hjfok / April 15, 2010 11:46 AM PDT
In reply to: Auto Focusing Problem

Most are operator errors, one need to learn how to focus with D-SLR since the depth of field is shallower than PS cameras.

But in case you are one of the very few who bought a camera/lens with focusing problem, you can try out the testing method from this link:

Collapse -
Filter issue?
by LucJs / April 28, 2010 3:48 AM PDT
In reply to: Auto Focusing Problem

Are you using a polarizing filter on the lens? That may also cause problems with autofocus.

Popular Forums
Computer Help 49,613 discussions
Computer Newbies 10,349 discussions
Laptops 19,436 discussions
Security 30,426 discussions
TVs & Home Theaters 20,308 discussions
Windows 10 360 discussions
Phones 15,802 discussions
Windows 7 7,351 discussions
Networking & Wireless 14,641 discussions

CNET Holiday Gift Guide

Looking for great gifts under $100?

Trendy tech gifts don't require a hefty price tag. Choose from these CNET-recommended useful and high-quality gadgets.