what to do if lens backfocuses

[Mocking-DX]

i just noticed today my 24-70L has a slight backfocus especially if open wide
probably about half to cm away
I found this out when i let it autofocus then turn the focus a touch then the picture i'm focusing comes out sharp.

It's out of warranty
can i send the lens to canon? how much am looking to pay?

thanks guys

[I Simonius]

i just noticed today my 24-70L has a slight backfocus especially if open wide <snip>

perhaps try adjusting the carburettor. Otherwise it's probably the advance/retard mechanism.





( I thought you said backfires! -sorry- in a silly mood :lol: )

[JK]

i just noticed today my 24-70L has a slight backfocus especially if open wide
probably about half to cm away
I found this out when i let it autofocus then turn the focus a touch then the picture i'm focusing comes out sharp.

It's out of warranty
can i send the lens to canon? how much am looking to pay?

thanks guysDo what I did: Send it to Canon to be re-calibrated, get it back, test it and then send it in AGAIN because they didn't do the job right... GRRR!!!:confused:

[ron chappel]

Yep canon can fix that.
I had a 75-300 IS that consistantly front focused and they got it bang on.They way they do it here in australia is that they simply have a standard service charge for different model lenses which includes a thorough check,clean and calibration .I presume they'd have a similar system where you are.Mine cost the eq. of us$70 but i've heard usa service prices may be a little higher

[Mocking-DX]

thanks a lot guys
Simon: you silly man

Iwas actually gonna buy a new 1 and sell this, but i guess having it re calib is cheaper for me

[I Simonius]

Yep canon can fix that.
I had a 75-300 IS that consistantly front focused and they got it bang on.They way they do it here in australia is that they simply have a standard service charge for different model lenses which includes a thorough check,clean and calibration .I presume they'd have a similar system where you are.Mine cost the eq. of us$70 but i've heard usa service prices may be a little higher


sorry offtopic...
Ron - interested that you're doing a lens comparison - keep us postyed if you do one that includes the 100-400 IS lens?

[rent]

you really want to first find out if it's your lens that is back focusing, or your camera, or both. if you have several other lenses, and they all focus spot on, then it's probably the lens. if all lenses back focus it could be your camera's AF system that needs adjustment.

-alex

[Mocking-DX]

thanks rent
I did use my 50mm 1.4 wide open and it was ok

then i tried the 24-70 and 50mm on my rebel, same result