Photography: Why does my lense/camera NOT FOCUS PROPERLY with manual mode???

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Batman

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#41594 19-Sep-2009 10:50

I have a Canon 400D with stock 18-55mm (NON IS).
With auto modes pictures are USUALLY sharply focused.

With manual modes (eg P/Tv/Av) i have to take multiple shots to get one picture that is sharply focused. This is with shooting at Large Fine/RAW, WITH a tripod. no shaking. the same whether i use single point focus or multi point focus.

You can't notice it if glancing at it in say 800x600 size ie half monitor size but if you take it up to say 1280x1024 ie fill my monitor or at full pixel size they're awfully out of focus.

At first i thought it's normal, but hey, in auto mode its bloody sharp! so?? lense problem? body problem? normal?

The shop can't tell me why. All they say is why dont you buy our lense instead.

alasta

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#256996 19-Sep-2009 11:40

So, to clarify, you're taking shots of exactly the same scene in different exposure modes but in P/A/S/M modes the part of the frame where the focus point was selected is not sharp?

I think you need to put up a handful of in-focus and out-of-focus shots on a photo viewing site which supports the display of EXIF data as that will give some good clues as to what's going on.

If parts of the frame away from the point of focus are sharp in some shots but not others then that would most probably indicate variances in the depth of field, but if the exact point of focus is not sharp then that seems very odd.

Batman

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#257025 19-Sep-2009 14:48

okay i thought someone would ask for a sample - too bad i've deleted the 'bad shots' in the past. will try to get the tripod out and do some more "testing" and post on flickr or something.

thanks

TinyTim

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#257524 22-Sep-2009 10:58

Assuming the focus is working ok... what aperture setting are you using?

For all lenses: the area in focus generally loses sharpness beyond f/8 due to diffraction.

For your lens: this is a cheap lens that is let down when it is fully open; the fully auto settings generally try to use nothing too extreme in its settings. If you're using f/3.5 at the widest angle you could be seeing lens issues: 'However, technically the resolution is mediocre all-in-all and at 18mm @ f/3.5 it's downright poor' (review from PhotoZone)

(EDIT: these are not focus issues but resolution or quality issues)

kiwipawl

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#257537 22-Sep-2009 12:13

Are the photos that are out of focus raw formatt?

Bung

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#257553 22-Sep-2009 13:25

joker97: I have a Canon 400D with stock 18-55mm (NON IS).
With auto modes pictures are USUALLY sharply focused.

With manual modes (eg P/Tv/Av) i have to take multiple shots to get one picture that is sharply focused. This is with shooting at Large Fine/RAW, WITH a tripod. no shaking. the same whether i use single point focus or multi point focus.

Are you talking Auto as in square box AUTO mode or A-DEP that picks Depth of Field? From the Function Availability Table at the back of the manual in AUTO and A-DEP mode you only have auto focus point selection not manual. Are you using the same focus point in the other modes that the camera is selecting? In P which is basically just Auto with more options you should see the same results with AF set to auto point.

Batman

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#257649 22-Sep-2009 20:27

i dont think it's anything to do with aperture etc ... the lense just does not focus on the thing i'm telling it to focus on ... actually i think the problem may be better with multi point focus, but havent had a chance to do more testing just yet.

yes the same in raw - as i said, it's a focus thing. shooting around 24mm with f/4-ish aperture - yeah i should've been using f/8 but hey it should not be out of focus what ever i do!

yes auto as in green rectangle - which the wife uses... perhaps she's a better photographer but as i said, it is out of focus using P! argh - will post pics once i get around to doing properly controlled tests

TinyTim

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#257655 22-Sep-2009 20:36

Use this focus test: http://photo.net/learn/focustest/

Use with and without a tripod and you can see how steady you hand is :-)

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Batman

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#257661 22-Sep-2009 20:51

good one mate! that's the best controlled test one can do - perhaps this weekend.

drspangle

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#258365 25-Sep-2009 15:37

Im not that familiar with canons autofocus system, but is it possible that with the scene modes it uses a particular autofocus point selection method (be it automatic or manual, like I said, I've barely touched canon's DSLRs..) and when you shoot in x-priority (Tv/Av/M) mode it is defaulting to something else and you havn't noticed?

Besides that I'd imagine the aperture is open wide on your shots, whereas the camera knows in the auto modes to avoid it whereever possible (you will have both shallower depth of field and your lens won't hold up all that well at f/4.5 vs f/8 - it might LOOK out of focus but it might just be very soft - it's not a high end lens after all)

Bung

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#258376 25-Sep-2009 16:09

drspangle: Im not that familiar with canons autofocus system, but is it possible that with the scene modes it uses a particular autofocus point selection method (be it automatic or manual, like I said, I've barely touched canon's DSLRs..) and when you shoot in x-priority (Tv/Av/M) mode it is defaulting to something else and you havn't noticed?

I've covered that aspect. In the scene modes it only uses auto AF point selection. In P mode you can have either manual or auto but the camera should still be picking aperture and speed in the same way as Auto unless the ISO is different.

The focus test is useful for forward or back focus but may not help if it is a question of where in the scene the camera vs joker97 is focusing.