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50D Back from Canon - Focus lost when re-compose shot

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jayboo

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I think I am in a bit of a pickle. Spent the last couple of days doing focus tests on lenses - today taking same shots with 50d and 450d - 50mm 1.4 lens - made my poor dog sit still for quite some time.

I was delighted when Canon got my 50d back to me in a week after it had a multi controller fault - but - have not been completely happy with any shots - any lens - since then.

So - on the shots I have taken today - the 450d shots viewed at 100% in the main are much better. I also have noticed when reviewing the images - in DPP - show AF point - I use centre focus point - then recompose and shoot. My 450d stays put my 50d has not once maintained the focus point once it has just moved to the centre of the shot.

Can I be doing something wrong (of course I know I can) - is there a menu setting that I am missing somewhere.
Help please

--
Jayboo
 
One shot Focus Mode - Centre Focus Point only
--
Jayboo
 
the only way that would occur is if you are not AF locking before recompose.
 
OK - am I really not getting this - I thought with centre focus point selected - one shot mode - I could half press shutter button with focus point on say the eye - keeping shutter button down re-compose the fully press the shutter button and focus should have stayed on the eye. If this is not the case then all the books I have on 50D are WRONG.
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Jayboo
 
jayboo said:
OK - am I really not getting this - I thought with centre focus point selected - one shot mode - I could half press shutter button with focus point on say the eye - keeping shutter button down re-compose the fully press the shutter button and focus should have stayed on the eye. If this is not the case then all the books I have on 50D are WRONG.
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Jayboo
Click to expand...
The focus point should stay on the eye, however; when viewing the image in Zoombrowser your "used" focal point indicator will show as being where you --MOVED TO -- to for the re-compose.
I had basically the same inquiry several weeks ago in the below link:
http://forums.dpreview.com/forums/read.asp?forum=1019&message=32202831
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Vernon...
 
I hope your not trying to do that at F1.4? Are you??? If so then that may be your problem. You know, that is when the focus plane shifts slightly when you recompose and at such a narrow DOF it can make a difference. If so then you have to pick a different focus point to use to keep from recomposing so much or stop it down a little. Or both!

I feel like a broken record saying sample images help tremendously.
 
jayboo said:
OK - am I really not getting this - I thought with centre focus point selected - one shot mode - I could half press shutter button with focus point on say the eye - keeping shutter button down re-compose the fully press the shutter button and focus should have stayed on the eye. If this is not the case then all the books I have on 50D are WRONG.
--
Jayboo
Click to expand...
only if your configuration has both AE and AF lock on the shutter press.

which IMO .. is the worst possible configuration.
 
Right - OK - sorry I am not understanding you - are you saying this is something I need to set up in my Menu - if so how???
--
Jayboo
 
jayboo said:
Right - OK - sorry I am not understanding you - are you saying this is something I need to set up in my Menu - if so how???
--
Jayboo
Click to expand...
you know the manual is there for a reason ..

assuming the menus are the same on the 40D ... CFN IV-1 usually option 3 AE Lock/Metering + AF Start.

I do CFN IV-2 enabled because I have older XXD series and I like it on the * instead of the AF-ON button ..

however by default, if you are in one shot AF .. and assuming you haven't changed anything (or canon didn't by mistake and leave it) .. half shutter press will AE and AF lock.

however, as with anything confirm your settings.

and if you are recomposing after AF lock .. technique becomes the greater source of error than the camera with fast lenses.

let's put it this way .. if you shoot and don't recompose and the image is fine .. then it's the person behind the camera .. not the camera causing the problem.
 
I'm not as experienced or as clever as you obviously - I bow to your greater wisdom oh great one!!!!!

However - I have read my manual - I have read Canon eos 50d Digital Field Guide - I have read Canon 50d from snapshots to great shots - I have Canon 50d Crash Course DVD - all books I have read over and over again - the manual is by my side - the DVD I watch avidly including the very boring menu section.

So - yes - as you say - by default - my camera should perform as stated by me AND IT DOESN'T.

I have also researched all the forums on here and elsewhere - and as usual with forums - like the Jewish committee - end up as confused as I started - with so many differing opinions.
So what now clever clogs!!!!! Back to Canon or what!!

END LINE - THE CAMERA IS NOT FOCUSSING WHERE IT SHOULD BE - ALL IMAGES SOFT - EVEN WITH THE MIGHTY 50MM 1.4 ON ALL APERTURE VALUES.

The images I took before I returned it to Elstree to repair the Multi Control Function problem are all way ahead of anything I have taken since its return - please don't tell me I have gone completely senile in the last three weeks - I know I have had the odd glass of wine - and yes - resorted to the odd cigarette at times of extreme stress - But - I simply don't believe itts just ME!!!
RANT OVER
--
Jayboo
 
Couple of questions -

You mentioned that you were comparing 100% crops. You do understand that, viewed at 100%, the 450D image will appear sharper than the 50D images because you're magnifying less?

(This is a very common mistake when comparing 100% magnification).

Compare at the image level - at the same size, and identify the sharpest point in the image. Where is it?

Do a test focus-and-recompose, at your widest aperture, from a close focus subject to a far one. Can you hear or feel the AF motor moving?
 
jayboo said:
I'm not as experienced or as clever as you obviously - I bow to your greater wisdom oh great one!!!!!

However - I have read my manual - I have read Canon eos 50d Digital Field Guide - I have read Canon 50d from snapshots to great shots - I have Canon 50d Crash Course DVD - all books I have read over and over again - the manual is by my side - the DVD I watch avidly including the very boring menu section.

So - yes - as you say - by default - my camera should perform as stated by me AND IT DOESN'T.

I have also researched all the forums on here and elsewhere - and as usual with forums - like the Jewish committee - end up as confused as I started - with so many differing opinions.
So what now clever clogs!!!!! Back to Canon or what!!

END LINE - THE CAMERA IS NOT FOCUSSING WHERE IT SHOULD BE - ALL IMAGES SOFT - EVEN WITH THE MIGHTY 50MM 1.4 ON ALL APERTURE VALUES.

The images I took before I returned it to Elstree to repair the Multi Control Function problem are all way ahead of anything I have taken since its return - please don't tell me I have gone completely senile in the last three weeks - I know I have had the odd glass of wine - and yes - resorted to the odd cigarette at times of extreme stress - But - I simply don't believe itts just ME!!!
RANT OVER
--
Jayboo
Click to expand...
you know, you're the one that posed a problem with a very lacklusture description surrounding focus and recompose .. which is SKILL related .. focus and recompose on a high Mp / density sensor requires technique to do it well.

did you check your focus adjustment settings after getting it back?

rant all the bloody hell you want, you're the on posting asking for help on a public forum .. you don't like the responses, then figure it out yourself, it's not my bloody problem - it's yours and none of us in here get paid to assist YOU in your issues.

so again, check all your settings, revert back to default if you have to and at least clearly identify the problem so people can help.

it's very "unusual" for it to be soft in all apertures, because as you stopped down your DOF would increase - sooner or later your plane of focus would be close enough to your target unless your focus adjustment is way off.
 
Pleaase note - as frustrated as I am I haven't had to resort to bad language - have you had a bad day - shame!!!
Again - camera settings are on default

My question is - all advice is I should be able to recompose a shot - whatever the setting - and the focus point (focus) should stay where I intended it to be.

Images posted below - 1st shot canon 50D - focussed on eye - re-composed - focus ended up around collar which when viewed large size I think you can see image is soft around eyes and sharp around collar area

2nd shot 450D taken in same manner - focus stayed around the eye even after I recomposed the shot.
I know neither image is great
That is not what I am talking about

Simply why I can't hold focus when I re-compose the shot on 50D when I do on 450D





--
Jayboo
 
Thanks for your input - I have posted some shots now - hopefully that will illustrate my problem - and in answer to your problem - no I cannot hear the AF motor
--
Jayboo
 
I don't think this is a focus-recompose problem.

I agree with you that the eye is not sharp, and the collar is, in the 50D shot.

However, I'm trying to identify the plane of focus, and not finding it. If the collar is sharp, then everything in the same plane as the collar should be sharp, too.

That means that the dog's head, behind the eyes, should be sharp. (I believe the collar is further away than the eyes - but I could be wrong. Nevertheless, the dog's nose isn't sharp either, so if the collar is closer than the eyes, that doesn't solve the problem). Instead, however, the back of the dog's head is less sharp than the eyes.

If this were a focus problem, then some part of the dog's head (nose, eyes, forehead, top of head, etc) would be sharp. The sharpest part of his head, however, is maybe the fur between his eyes - at almost the exact same focal distance of his eyes. That area still appears less sharp than the collar ...

That leads me to believe that this is a motion blur problem, NOT a focus one.

What was your aperture on this? What was your shutter speed?
 
Right - Shot this on AV Mode - with value of 7.1 - shutter 1/15 - Hands Up - not meant as a pun - I have not got the steadiest hands in the world and I can see where you are coming from - however - that - maybe because I am THICK - still does not explain to me why the point of focus shifts when I re-compose the shot - unless you are suggesting my hands are extremely unsteady.

Now I look at the settings - I would widen the aperture and increase the shutter speed - maybe the ISO and I'm sure I probably did this on later shots as that is how I tend to do things - look at what I've got and take it from there - I will look through the shots and see if I can find a different example

I have no problem accepting this is my error not the camera's - I would prefer that to be so - but the shots I have posted are two out of forty - there may have been some that would have better showed where I am coming from.

--
Jayboo
 
jayboo said:
Right - Shot this on AV Mode - with value of 7.1 - shutter 1/15 - Hands Up - not meant as a pun - I have not got the steadiest hands in the world and I can see where you are coming from.
Click to expand...
there's no chance you are going to get a picture of a dog to have hair in focus without micro motion blurr on a 50D at 1/15th of a second.

which is why the collar looks in focus and the rest doesn't .. hair moves .. and 1/15th is just dog slow (pardon the pun).

you simply will not get that shot unless you are way above that in shutter speed.
 
Hmmm - perhaps its my eyes then - but to me the hair below the collar looks pretty well focussed - I agree shutter speed need to be faster - my object was to test if camera was holding focus when I re-composed - again I repeat - it did on the 450d not on the 50d

Whilst I myself can be critical on the shots and I agree with your comment - does that really explain why focus has shifted???

I am seeing the other comment about shift of focal plane when re-composing but I am not sure that totally explains results on the 50d shot - I can see that on the 450D shot however
--
Jayboo
 
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