my 70-200 f/4 backfocuses. will canon calibrate it for free ?

sequitur · 16th February 2004

hi guys.

did a ruler test coz i suspected my f4 of backfocusing.

will canon calibrate it for free ?

and uh
where can i find canon service centre

must it be under warranty ?

sequitur · 16th February 2004

wait

on second thoughts

maybe my 10D is the one backfocusing

sequitur · 16th February 2004

and oh.

my warranty is unfilled and it's like 1 month overdue.

so how ah ? :P

they must see receipt ah

can i just backdate to the date of the receipt and so be it ?

Ah Pao · 17th February 2004

Just go to the Canon Service Centre at HarbourFront and you can get all your questions answered.

http://www.canon.com.sg/index.cfm?fu..._type=showroom

My advice would be to give them a call before going down. They're pretty knowledgable over the phone as well.

keithjhee · 17th February 2004

sorry, OT abit..but can you enlightment me wat is backfocus?? thanks for sharing..

keith

sequitur · 17th February 2004

backfocus =

if your subject is let's say 5m away from you

the camera's AF sort of reads it as 5.1m instead of 5m and sends the wrong focus info to the lens and so the lens focuses the wrong distance (which is at the back of the intended subject) so that's backfocus

frontfocus = same reasoning but it's in front instead.

kiwi2 · 17th February 2004

Can back focus be due to the camera body or lens itself or even a combination of body+lens? I only heard this term being used with DSLR, especially 10D. Never had this problem with film bodies or even my D30.

How do you suspect it? Pictures always turn out less than ultra sharp even though it's an 'L'?

Thanks.

sequitur · 17th February 2004

yes
you won't really notice it at the wide ends like 15-17mm

but once you start using a zoom lens, you'll notice it
that your pictures aren't sharp
it's just that weird feeling

anyway shot a ruler
and it sorta proved me right
that my camera was backfocusing

focus on a number ( i focused on "3") and the focus was in between "3" and "4" instead.
all my lenses exhibited this issue so it's probably my 10d

shot the same thing with my sony 717 just to be sure, and nope the 717 had perfect focus. "3" was directly in focus right smack in the middle and focus faded off towards "2" and "4".

sequitur · 17th February 2004

Originally Posted by kiwi2

Can back focus be due to the camera body or lens itself or even a combination of body+lens? I only heard this term being used with DSLR, especially 10D. Never had this problem with film bodies or even my D30.

How do you suspect it? Pictures always turn out less than ultra sharp even though it's an 'L'?

Thanks.

yes can be due to either/or/both

my 10d is newbatch
but apparently the problem didn't get solved.

16th February 2004	#1
sequitur Senior Member Join Date: Apr 2003 Posts: 2,825	my 70-200 f/4 backfocuses. will canon calibrate it for free ? hi guys. did a ruler test coz i suspected my f4 of backfocusing. will canon calibrate it for free ? and uh where can i find canon service centre must it be under warranty ? __________________ my flickr.

16th February 2004	#2
sequitur Senior Member Join Date: Apr 2003 Posts: 2,825	wait on second thoughts maybe my 10D is the one backfocusing __________________ my flickr.

16th February 2004	#3
sequitur Senior Member Join Date: Apr 2003 Posts: 2,825	and oh. my warranty is unfilled and it's like 1 month overdue. so how ah ? :P they must see receipt ah can i just backdate to the date of the receipt and so be it ? __________________ my flickr.

17th February 2004	#5
keithjhee Member Join Date: May 2003 Location: toa payoh Posts: 270	wat is backfocus huh? sorry, OT abit..but can you enlightment me wat is backfocus?? thanks for sharing.. keith

17th February 2004	#6
sequitur Senior Member Join Date: Apr 2003 Posts: 2,825	backfocus = if your subject is let's say 5m away from you the camera's AF sort of reads it as 5.1m instead of 5m and sends the wrong focus info to the lens and so the lens focuses the wrong distance (which is at the back of the intended subject) so that's backfocus frontfocus = same reasoning but it's in front instead. __________________ my flickr.

17th February 2004	#4
Ah Pao Member Join Date: Nov 2003 Location: Singapore Posts: 1,578	Just go to the Canon Service Centre at HarbourFront and you can get all your questions answered. http://www.canon.com.sg/index.cfm?fu..._type=showroom My advice would be to give them a call before going down. They're pretty knowledgable over the phone as well.

17th February 2004	#7
kiwi2 Member Join Date: Feb 2003 Posts: 1,253	Can back focus be due to the camera body or lens itself or even a combination of body+lens? I only heard this term being used with DSLR, especially 10D. Never had this problem with film bodies or even my D30. How do you suspect it? Pictures always turn out less than ultra sharp even though it's an 'L'? Thanks.