back focusing on my 7d

[berryhappening]

hi everyone ... i just did a wedding photoshoot ..i am using a 17-35 lens ...what i enounter is that the object is blur and the surrounding is clear,, just what to ask whether anyone encounter this problem ...day shooting is ok ... by come to nite time the camera go hay wire ... keep on searching for the target... then when you got everything within the frame or the centre square lite up ... the picture came out blur for the people and the surrounding is clear ...can anyone help me with it ....


.setting .. 1/30 4 iso 400 flash at 1/2 setting ..flash: 5600
this is the setting i set for most of the table shots and i having been using this seeting for quite a few weddign already ... only yesterday nite i have this problem and one more thing is that the camera hang two time yesterday ... wah lau dont know what happen leh ... the only thing i notice is that for the previous two shoots i use 4 np400 . 2 for the morning and 2 for the evening ... yesterday i use 2 for the whole day ... and it last me all the way ... (no time to charge the other two )


help ??

[Magnus Wedberg]

Originally Posted by berryhappening hi everyone ... i just did a wedding photoshoot ..i am using a 17-35 lens ...what i enounter is that the object is blur and the surrounding is clear,, just what to ask whether anyone encounter this problem ...day shooting is ok ... by come to nite time the camera go hay wire ... keep on searching for the target... then when you got everything within the frame or the centre square lite up ... the picture came out blur for the people and the surrounding is clear ...can anyone help me with it ....

Please post example shots so we can see what's happening...

[UY79]

The camera sometimes locks on to the brighter background because the edge contrast in the background is easier to detect than the subject.

Cheers!

[Flare]

Hee hee... and do note that AF point lighting up when you are shooting using the "Focus Area Selection" mode does not indicates that the camera has achieved focus... It's just light up to show which one is the selected AF point... And if you set your camera to able to release the shutter before focus is locked, you could get OOF images...

[UY79]

Originally Posted by Flare Hee hee... and do note that AF point lighting up when you are shooting using the "Focus Area Selection" mode does not indicates that the camera has achieved focus... It's just light up to show which one is the selected AF point... And if you set your camera to able to release the shutter before focus is locked, you could get OOF images...

Even with single AF point, you still will get OOF if the background is brighter.

Cheers!

[-7-]

back focusing, looks like it is a very subjective matter... if that's the case (as in it could be the background is brighter or situation similar to this), who is in the correct position to state it is really back focus and not the photographer / the condition thingy? For the past cases happened in other brand of DSLR, back focusing was discovered by their own technical team then came out with an upgraded firmware as a solution? I am just curious... pls. help me to understand the flow in this matter

berryhappening, a hidden 7D owner who is not listed (or dun wanna be listed)

Cheers...

[deslim27]

Originally Posted by -7- back focusing, looks like it is a very subjective matter... if that's the case (as in it could be the background is brighter or situation similar to this), who is in the correct position to state it is really back focus and not the photographer / the condition thingy?

How does a 'brighter background' affect the AF accuracy?

Originally Posted by -7- berryhappening, a hidden 7D owner who is not listed (or dun wanna be listed)

Since forbyte wish not to be included in the list, I've not update the list unless owner post in the '7D Owner' thread..

[Drudkh]

You already stated clearly that you've used the same set up for past few weddings and no problem but the recent one. do you still think its has back focusing problem? Show us some photos, at least one with the clear shot and another with the problem.

[berryhappening]

just one very stupid question how do i attach the pics ... i have been trying to figure this out for the past 15 min ..

[Drudkh]

Originally Posted by berryhappening just one very stupid question how do i attach the pics ... i have been trying to figure this out for the past 15 min ..

no prob, its not stupid question.
i use http://www.imageshack.us to upload
and post the link here.

[-7-]

Originally Posted by deslim27 How does a 'brighter background' affect the AF accuracy?

this one must ask UY79, I quoted his comment one

Originally Posted by deslim27 Since forbyte wish not to be included in the list, I've not update the list unless owner post in the '7D Owner' thread..

Wakata

[berryhappening]

but one thing is that if this is happening to this camera ... then when we shoot anything it will just focus anywhere which is brigther than the subject itself ... pardon me for my ignorance ... cos when it come to table shots the ambient usually quite dim for some hotel .. so if the camera tends to choose focus on anything then the subject itself ... that will be quite a headache .. i use wide sfocusing too ... same effect .. so i really hope to find an answer to it ...
1. dont know whether camera have anyproblem ?
2.battery problem ? (power no eough cos of anti-shake )
3.flash metering problem .( 5600hs metering not accurate )
4. focusing of the camera ...

i have a lot of question now .. just trying to the nearest possibilites ...

[forbytes]

Please enlighten me. Why does people start to complain front focusing or back focusing for DSLR? I thought the AF technology the same between film and DSLR right? Why are they more prone to such focusing problems? I have not encounter such problems (in weddings and events) with Dynax 7 and even 505SI. I sound like a newbie.

[berryhappening]

hi forbtyes the thing is that if my set of camera is faulty then i will go and get the things fix ...to me when the cam come out from the production line maybe 8-9 set are good and i may be the only one getting the 1-2 sets ... hope you understand what i mean ... so if that is the case then i cannot go on taking pics without rectifying the probelm that i encounter ,i have 505si ... i like you too have no problem with it ... i have a olympus 5050 have no problem with it ... until i switch to 7d ... now have problem .

[deslim27]

Originally Posted by berryhappening but one thing is that if this is happening to this camera ... then when we shoot anything it will just focus anywhere which is brigther than the subject itself ... pardon me for my ignorance ... cos when it come to table shots the ambient usually quite dim for some hotel .. so if the camera tends to choose focus on anything then the subject itself ... that will be quite a headache .. i use wide sfocusing too ... same effect .. so i really hope to find an answer to it ...

You mean your AF setting is Wide Area AF? Probably, yes.. I think the camera will pick the easiest point to focus?

I never use Wide Area AF before actually, I choose the AF point that I need.. no confusion

[berryhappening]

here is the link to the photos ... http://pg.photos.yahoo.com/ph/vinced...bum?.dir=/a9de

[-7-]

Originally Posted by berryhappening here is the link to the photos ... http://pg.photos.yahoo.com/ph/vinced...bum?.dir=/a9de

woooohhh a pic. tells a thousand words...
1 quest.: Was your focus pt. locked on your desired subject just before you pressed the shutter button?

[berryhappening]

yes it is locked on and depress and not onwide focusing ... i select the centre focus point and the cnetre box light up and well this is the result that i get .... blur on the subkect and clear on the surrounding
and the flash ... cos the celling is quite high so i use a bounce car and very small one ... and all the flash fall on the face itself ... i shot the second time same result ..

[deslim27]

Hi All,

Some studies show that there could be a few possible reasons for bad focusing on DSLR (which based on film SLR AF technology).. If you can read German.. this is the article.

http://www.colorfoto.de/sixcms/media...fokus_cofo.pdf

Dat Ei from dpreview translate the content briefly here..

http://forums.dpreview.com/forums/re...ssage=11268445



As I wrote some days ago the german photo magazine "Colorfoto" researched the possible reasons for AF problems of DSLRs. Here is a short listing:

1.) misadjustment of the AF sensor


2.) IR- and antialiasfilter in front of the chip incfluencing the path of rays (Remember that the AF sensor is at the bottom of the cam. The optical path throgh the lens to the AF sensor differs from the optical path to the chip.)

3.) Pixels are smaller than film grain, so that the tolerance of a DSLR AF is smaller than the one of a SLR AF. In case of old lenses (heavy used or cheap ones) you might get problems as the drive control isn't that accurate. Focus point might vary from shot to shot.

4.) The focus point is measured with a total open aperture. Some lenses show the effect, that the focus points varies in dependence of the effective aperture. In combination with the small tolerance of DSLR AF systems you might get AF problems.

5.) The concavity of the field of view might lead to AF problems, especially if you use wide angle lenses.

6.) Drive control of the lens might stop to fast or to slow. This is a question of adjustment.

7.) Misalignment of lenses


As you can see, a DSLR AF isn't that simple and if you have AF problems it isn't that simple for a laities to diagnose the deciding reason(s). So before you can blame the KM engineers or the KM management for those problems, let's check your cam and the problematical lens.

Here is the link to the german article:

http://www.colorfoto.de/sixcms/media...fokus_cofo.pdf


Just my 2 cents

Dat Ei
--
'Charter Member of the Konica Minolta 7D Adoption Society'

[berryhappening]

well my lens config for the nite ... tamoron 24-135 3.5 5.6 and the new minolta 17-35 (d) 2.8-4 maybe my 7 d need to go do some checkup already