Canon 40d - manual focus not sharp but autofocus is sharp.

_andyjb

_andyjb

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andy
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Hi all

After praising Canon service centre last week, i may have to re-think my opinion. I am going back there later this week now.

Here's my problem... My 40d was calibrated last week and autofocus is nice and sharp on a variety of lenses - 24-105L, 50mm f1.8 and an 18-55mm IS. However when i switch to manual focus, the same image, when re-taken, is out of focus using any of the above lenses.

Trying the same lenses on auto focus and manual focus on a 1000d results in all images being sharp.

The problem seems to be getting an AF point lock in manual focus on the 40d. When using autofocus and the centre AF point, i get a lock and sharp image, when using manual i just don't get the AF point at all and even though the image looks sharp in the viewfinder it is out of focus when the resultant image is viewed. I thought it may have been the diopter and that i wasn't the seeing it clearly but i've discounted that. (on the 1000d in manual focus, i get the AF point and a sharp image as a result.)

Does anyone have any ideas for solving this? Is there a custom function that i'm missing that would help?

Thanks

andy
 
Ummm when you have a lens in manual focus it is your own eye and the manual focus ring that will bring the image you want into focus. The AF points on the camera are just what they say they are Auto Focus points, they will not be used in manual focus is enabled on your lens. The camera body will do nothing but meter and record the image when the lens is swirched to manual.

I do not know how you managed to get crisp images on your 1000d when your lens are switched to manual focus other than it was an absolute flook.

Are you sure you aren't confusing the manual setting on the camera body i.e. changing aperature and shutter speed independantly and manual focus on your lens body.
 
Thanks Donki but from my understanding i should be able to get an AF point when focus is achieved but i do understand what are saying. And this is exactly my frustration, looking through the viewfinder and using manual focus ring, the image looks sharp. It is when i come to view the captured image that it is out of focus.

Donki said:
Are you sure you aren't confusing the manual setting on the camera body i.e. changing aperature and shutter speed independantly and manual focus on your lens body.
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LOL. no.

I'm not particularly worried about whether i get an AF point, it's more the fact that autofocus works when using the centre AF point but switch to manual focus and the image is soft.

andy
 
When manually focussing on my 50D (and I'm sure it was the same on the 40D) I'm sure I can get the focus point to 'ping' red when I've adjusted right.

What mode are you shooting in - single shot rather than AI Servo or AI focus?

My other thought is are you focussing by eye? If so is your dioptic eyepice setting changed? (the tiny wheel by the eyepiece)
 
Are you actually focusing ?
I mean... forget af points etc etc.. thats all null and void as soon as you switch to mf..
You are actually using the focus ring right? :thinking:
 
Focus confirm is still available in MF by pressing and holding the shutter button half down (or rear button if you use that) while twiddling the MF ring. When you get a good focus the focus point selected flashes red, and the focus 'circle' (in the bottom right of the VF on my camera) stays on as long as you have your focus engaged. I found MF very difficult indeed with my 450D and more a matter of trial and error, but I was using it at the time as I believed the camera was not AF'ing right.

It doesn't sound like the OP is doing anything wrong but I have never heard of a focussing problem like this I have to say.
 
Byker28i said:
When manually focussing on my 50D (and I'm sure it was the same on the 40D) I'm sure I can get the focus point to 'ping' red when I've adjusted right.

What mode are you shooting in - single shot rather than AI Servo or AI focus?

My other thought is are you focussing by eye? If so is your dioptic eyepice setting changed? (the tiny wheel by the eyepiece)
Click to expand...

I've checked the dioptic and it's ok. Will need to check shooting mode though, could this be the issue?

Trev Rich said:
Are you actually focusing ?
I mean... forget af points etc etc.. thats all null and void as soon as you switch to mf..
You are actually using the focus ring right? :thinking:
Click to expand...

Yep i'm using the focus ring right. lol. As Byker says though i should still get a focus point blink red which just doesn't happen.

andy
 
_andyjb said:
Thanks Donki but from my understanding i should be able to get an AF point when focus is achieved but i do understand what are saying. And this is exactly my frustration, looking through the viewfinder and using manual focus ring, the image looks sharp. It is when i come to view the captured image that it is out of focus.



LOL. no.

I'm not particularly worried about whether i get an AF point, it's more the fact that autofocus works when using the centre AF point but switch to manual focus and the image is soft.

andy
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Apologies for the silly question :), I couldn't think of anything else it could be.
 
_andyjb said:
I've checked the dioptic and it's ok. Will need to check shooting mode though, could this be the issue?
Click to expand...

Yup, in AI Servo or AI focus you don't get the focus point light up as it's continuously focussing.
 
A stupid question, do you have the diopter wheel on the veiwfinder set off slightly. It may sound daft but worth looking at.

It doesn't matter what you see on autofocus through the veiwfinder, the camera will still focus.

It's a slightly different matter on manual focus.

Whats it like on liveveiw ?

Just me thinking out loud with a knackered old brain......
 
Byker28i said:
Yup, in AI Servo or AI focus you don't get the focus point light up as it's continuously focussing.
Click to expand...

Ahh, i see your point about getting a focus point, but then how could it continually focus if i've set the lens to manual focus, and would this result in an OOF image?

andy
 
ChrisH said:
A stupid question, do you have the diopter wheel on the veiwfinder set off slightly. It may sound daft but worth looking at.

It doesn't matter what you see on autofocus through the veiwfinder, the camera will still focus.

It's a slightly different matter on manual focus.

Whats it like on liveveiw ?

Just me thinking out loud with a knackered old brain......
Click to expand...

I think the bigger issue is that on crop cameras the viewfinder is just too small to accurately manual focus. I tried for weeks before eventually giving up and realising I was getting far worse results than the camera's AF.
 
ChrisH said:
A stupid question, do you have the diopter wheel on the veiwfinder set off slightly. It may sound daft but worth looking at.

It doesn't matter what you see on autofocus through the veiwfinder, the camera will still focus.

It's a slightly different matter on manual focus.

Whats it like on liveveiw ?

Just me thinking out loud with a knackered old brain......
Click to expand...

Thanks, Chris.

Diopter is set right as it looks ok and in focus when using autofocus as well as manual focus. Not checked on liveview to be honest, i never use it on the 40d.
 
Don't forget you can change the focus screen in a 40D, I can't bring to mind which is the one that you can get but I'm sure it has a split circle in the middle like old reflax camera's. Maybe worth shelling out a few quid. On the other hand I'd also check that the focus screen hasn't moved slightly during it's repair. It may have dropped in which case your focus would be off.

As for Canon service don't go there....................:bang:
 
trencheel303 said:
I think the bigger issue is that on crop cameras the viewfinder is just too small to accurately manual focus. I tried for weeks before eventually giving up and realising I was getting far worse results than the camera's AF.
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A fair point Trencheel.

ChrisH said:
Don't forget you can change the focus screen in a 40D, I can't bring to mind which is the one that you can get but I'm sure it has a split circle in the middle like old reflax camera's. Maybe worth shelling out a few quid. On the other hand I'd also check that the focus screen hasn't moved slightly during it's repair. It may have dropped in which case your focus would be off.

As for Canon service don't go there....................:bang:
Click to expand...

If the focussing screen is out would it not affect the autofocus as well though?
 
_andyjb said:
Thanks, Chris.

Diopter is set right as it looks ok and in focus when using autofocus as well as manual focus. Not checked on liveview to be honest, i never use it on the 40d.
Click to expand...

I would give Live view a go, zoom in 10x on it to get a perfcet focus and take your picture. That would rule out a problem with the viewfinder if it too is not in sharp focus.
 
It really depends, the viewfinder is so small that areas that seem sharp aren't necessarily so! View an image with narrow DOF on a big screen and you can clearly see which bits are in or out of focus. Shrink it down to the size of a postage stamp and much more of it looks in focus - see what I mean?
 
trencheel303 said:
It really depends, the viewfinder is so small that areas that seem sharp aren't necessarily so! View an image with narrow DOF on a big screen and you can clearly see which bits are in or out of focus. Shrink it down to the size of a postage stamp and much more of it looks in focus - see what I mean?
Click to expand...

I see what you mean, although in my case the shot looks sharp through the viewfinder in both autofocus and manual focus. It's only when you come to view the images that manual is out of focus.

andy
 
_andyjb said:
I see what you mean, although in my case the shot looks sharp through the viewfinder in both autofocus and manual focus. It's only when you come to view the images that manual is out of focus.

andy
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It will do. There is enough of a discrepancy for it to be a bother when viewing the images on a screen (or zooming in) but in the VF the difference is small enough to be undetectable.
 
If it's not sharp in MF, then you're just going blind...
 
It does beg the question that if you are using the focus confirm lights as your focus aid, then why don't you just use back button focussing? It will be far more precisely on the red light than your fingers could ever achieve.
 
grahamsewelluk said:
It does beg the question that if you are using the focus confirm lights as your focus aid, then why don't you just use back button focussing? It will be far more precisely on the red light than your fingers could ever achieve.
Click to expand...

thanks graham. I wasn't using the confirm lights as a focus aid, I just noticed that they didn't illuminate in manual focus mode when i saw the shot as in focus through the viewfinder. I wasn't aware that the 40d had back button focussing.

andy
 
Bang it in live view, then x10 it. Use live view to get the perfect focus.
 
Should have gone to specsavers.:):D:p
 
_andyjb said:
If the focussing screen is out would it not affect the autofocus as well though?
Click to expand...

No, the AF sensors are in the bottom of the mirror box and the light path goes nowhere near the focussing screen.

If manual focus looks good but the final image doesn't then it's usually neccessary to shim the focussing screen.

Last thought....if they've calibrated the body then there's a chance that they've nudged the screen and it's not seated properly. A good test for this would be to MF two shots....one focussed at the bottom of the viewfinder and another at the top....the results will vary if the screen is out of kilter.

Bob
 
Canon Bob said:
No, the AF sensors are in the bottom of the mirror box and the light path goes nowhere near the focussing screen.

If manual focus looks good but the final image doesn't then it's usually neccessary to shim the focussing screen.

Last thought....if they've calibrated the body then there's a chance that they've nudged the screen and it's not seated properly. A good test for this would be to MF two shots....one focussed at the bottom of the viewfinder and another at the top....the results will vary if the screen is out of kilter.

Bob
Click to expand...

Many thanks for explaining this Bob. :thumbs: Looks like you've hit the nail on the head. I'll test this out tonight.

Incidentally using liveview and manual focus resulted in a sharp image but although that's useful to know i'm not about to start taking photos with liveview all the time now.

Thanks everyone for the input. I'll see what happens with Bob's test this evening and then take it back to Canon.

andy
 
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