Problem on my Lens?

[TuTu_CaR]

Hi guys,

I just realised for my KM 17-35mm lens, alot of times, the photos come out, my subjects are OOF. the ones in focus are those things are at the back...
is this lens suffering from the so called back-focus problem?

how to remedy? how to confirm?

[tankm]

If you have other lens, try those as well and see if the same problem happens ? If all have the same problem, then it's the camera and not the lens.

Originally Posted by TuTu_CaR Hi guys, I just realised for my KM 17-35mm lens, alot of times, the photos come out, my subjects are OOF. the ones in focus are those things are at the back... is this lens suffering from the so called back-focus problem? how to remedy? how to confirm?

[TuTu_CaR]

my 24-105 and 50mm no problem
100mm marco only use MF so dunno
this 17-35 seems to make my foucsing very difficult..
during wedding table shots have to use MF to be certain
during candid shots, this lens always seem OOF
even though the camera show the focus dot and i focus locked onto the subject....

think i try on a ruler.... if really got problem how?

[Agetan]

Focussing with wide angle is tricky... try to shoot at smaller aperture like f5.6 or f8 that should ok.

If prove that your lens is backfocusing, get it fix from Sony service center lor.

Hart

[tankm]

SONY Service center....any they may need your cam as well.

Originally Posted by TuTu_CaR my 24-105 and 50mm no problem 100mm marco only use MF so dunno this 17-35 seems to make my foucsing very difficult.. during wedding table shots have to use MF to be certain during candid shots, this lens always seem OOF even though the camera show the focus dot and i focus locked onto the subject.... think i try on a ruler.... if really got problem how?

[TuTu_CaR]

I done some test on a ruler just now... can confirm got some problem focusing at 17mm??

Settings: ISO 1600, F2.8 1/500secs

Focus was on 10cm point


17mm

35mm

[GENO]

R u too near the object? Is it out of focus?

[TuTu_CaR]

too near cannot focus...
i keep moving away
until the camera show the focus DOT in the viewfinder loh

wrong way of testing?

sorry..forget to mention..the images were cropped

[GENO]

did u set yr camera body on a tripod?

[TuTu_CaR]

nope...never set...
iso 1600 still have to set?

[GENO]

i never test on iso 1600 free hand before mah?? haha

[TuTu_CaR]

speed 1/500secs + anti shake leh
haha

so how
got problem right?

actually ever since i got this lens ...i feel there is some problem liao
everytime i go home see photo...some photos are always OOF !
strange leh..i always wait unti that dot come out...+ subject not moving
how come oOF !

then i shoot my cousin wedding also like tt during the testing day
then dulan actual day use MF for table shot.... heng some dude mention u put MF at 3M...everything sharp sharp...

[tokrot]

yes, i did almost the same test and had the same results last time. I thought it was the lens prob until I read some one mentioned tricky focusing with wide angle. I think it's quite normal for wide angle. You can set aperture to f4 ( in my case) and above to correct the OOF problem (to increase DOF). Correct me if I am wrong.

[TuTu_CaR]

hmmmm
okok
i try 2molo night again....
i tot even at F2.8...the point i focus on should be sharp....
then the one at the back should be blur......
nvm i try again loh

[tokrot]

Originally Posted by TuTu_CaR hmmmm okok i try 2molo night again.... i tot even at F2.8...the point i focus on should be sharp.... then the one at the back should be blur...... nvm i try again loh

Not really, you can read sulhan's post about 17-35mm lens which I also own one..

http://forums.clubsnap.org/showthread.php?t=179579

[GENO]

Originally Posted by TuTu_CaR hmmmm okok i try 2molo night again.... i tot even at F2.8...the point i focus on should be sharp.... then the one at the back should be blur...... nvm i try again loh

I did try shooting at f2.8, not bad loh, should be sharp at where u focus only...maybe , ur lens got a little OOF or its yr camera body??

[leeshock]

Originally Posted by tokrot yes, i did almost the same test and had the same results last time. I thought it was the lens prob until I read some one mentioned tricky focusing with wide angle. I think it's quite normal for wide angle. You can set aperture to f4 ( in my case) and above to correct the OOF problem (to increase DOF). Correct me if I am wrong.

I am using this lense as well. Shooting at 2.8 will give OOF pics.

[zcf]

Actually why shooting at f/2.8 (or wide open) for wide angle (like 17mm or a bit more) likely to cause OOF photo?