550D Back Focus assistance please!

dav3evans

dav3evans

Suspended / Banned
Messages
38
Edit My Images
No
Hey guys,

Need a bit of advice if possible, I've heard that the 550D can have issues with back focus, and after Googling the problem to death I did some tests and the results are below.

Links here are from my Sigma 17-70mm and my Canon 50mm, I always aimed at number 7, and tried both the centre focus point and the lower focus points:

17-70mm, centre point:

https://dl.dropbox.com/u/2408261/online_posts/LENS_TEST/17-70 centre aimed 7.jpg

17-70, lower centre point:

https://dl.dropbox.com/u/2408261/online_posts/LENS_TEST/17-70 lower aimed 7.jpg

50mm, centre point:

https://dl.dropbox.com/u/2408261/online_posts/LENS_TEST/50mm centre aimed 7.jpg

50mm, lower centre point:

https://dl.dropbox.com/u/2408261/online_posts/LENS_TEST/50mm lower aimed 7.jpg

So, having done the tests, and ignoring the super stylish piggy ruler I used ;) it looks like I have some issues.

What is my best move here? Does anyone have any recommendations on where I should send my kit to get checked out? It seems like both the lenses have an issue so I assume I should get it sent to Canon..but will they have an issue with me sending a Sigma lens too?

Oh, in addition, I did do this test with the AF on each lens, but I'm thinking that the AF and manual focus need testing, but whilst this needs looking at I figure I'd.......focus.......on this... :P

Anyway any assistance greatly appreciated. Cheers guys.
 
99% of the time I only use the centre focus point on my 550D, the outer ones just aren't as accurate. The picture from the 50mm using the centre point looks to be spot on to me. With the Sigma it looks like it has focused on the 8 instead.

Are you having problems when using both lenses or just with the Sigma?
 
I do feel like I'm having problems with both from time to time, but completely accepting of the fact that some of the time it will be my fault as well :) But if the camera/lenses aren't accurate I'll already be on the back foot so felt it was prudent to test.

You're right, the 50mm does look like it's hitting the right target on the centre point, which I'm hoping isn't me mis-remembering where I was aiming for.

I think as a test I'll get hold of some other bodies to check the lenses with. I know of another 550D and a 1000D that I could look at potentially.

I assume if I send off my camera and the Sigma lens Canon would calibrate it for me, though unsure if the adjustments that would potentially be made to the body would then have a knock on effect on the 50mm...
 
Ah, great link! Thanks for that dude I'll give that a try this weekend :)
 
batteries/cf cards is best test - charts require too much precision ie setting up at perfect angles - is too easy to get a false result

line some batteries/cf cards standing up in a diagonal line - focus on the middle one and then have a look at the outcome


________X
______X
____X
__X
X

____^ focus here
 
Ahh I hadn't thought of that. I sort of assumed I would need to use a chart or something with small increments on it to make sure I could see in enough detail.

I'll give that a go too. Thanks for the tip =]
 
Have you actually experienced any issues with your day to day shooting.

I'm a great believer in not going looking for a problem. Invariably consistent testing is not easy, the weakest link in the chain being the photographer. So I don't bother now unless I think there might be a problem.
 
Every now and again I have had a few problems, although not being pro I always assumed that it was because I wasn't getting something quite right, but I've had a few shots where I know that it should have been sharper than it was.

I think I am partly being a little paranoid as well, although now I have taken the time to test and feel like it might be a little out, I can't not continue to do a thorough test.

Coming from a technical background as well I like to be thorough, hence the need for additional bodies to try with the lenses etc...

Can anyone actually recommend anywhere I could take my gear rather than sending it to Canon? I think I'd feel a little weird about just dropping into Jessops and saying hey you! look at this for me *waves camera* especially if that's not something they would ever consider doing.
 
Don't go into Jessops, all they do is send it off to a repair centre and charge you for the pleasure.

I don't think there is anywhere you can just take it in for testing, best bet is to confirm a fault then pick your approved repair centre. Fixation in London are pretty good and do have a store, otherwise Canon elstree would be your best bet.
 
Ahh thanks Richard, I am in London so it might be an option for me to take it in there. Thanks! =]
 
You must log in or register to reply here.
Back
Top