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Eos 7D focus problem?

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cheddar-caveman
19 Mar 2013 - 3:39 PM

Scenario: 7D with Canon 300mm f4 + 1.4 extender mounted on solid tripod to take bird/nest pictires. IS off and AF on and picture taken. Reviewing the picture it looks blurred.

Switch of AF, turn on live view and go to 10X magnification. Manually focus so image is sharp on the screen. Take photo and it is still slightly blurred when reviewed.

As above but after focussing turn off live view and take photo and it still looks a bit blurred! (cap fitted over eyepiece.

Is not the picture one sees on the screen in live view what the sensor sees? If so,why would sceen be sharp and picture taken blurred???

Most puzzling!

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19 Mar 2013 - 3:39 PM

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justin c
justin c  104512 forum posts England36 Constructive Critique Points
19 Mar 2013 - 3:42 PM

It could be a million and one things!! Probably camera shake or heat haze.



Quote: Is not the picture one sees on the screen in live view what the sensor sees? If so,why would sceen be sharp and picture taken blurred???

The picture on the screen is before the picture was taken, which doesn't necessarily equate to the picture that's been captured, i.e. camera shake, subject movement, etc. etc.

Last Modified By justin c at 19 Mar 2013 - 3:47 PM
robthecamman
19 Mar 2013 - 3:46 PM

maybe extender

cheddar-caveman
19 Mar 2013 - 3:46 PM

I tried to totally iliminate any chance of camera shake - should have said I was using a remote release. No wind so absolutely no movement of tripod.

robthecamman
19 Mar 2013 - 3:48 PM

try without extender see wat that does

GlennH
GlennH  91896 forum posts France1 Constructive Critique Points
19 Mar 2013 - 3:49 PM

Is the shutter speed set sufficiently high?

justin c
justin c  104512 forum posts England36 Constructive Critique Points
19 Mar 2013 - 3:50 PM

Possibly heat haze. (Yes even at this time of year and the sun doesn't even have to be shining or the temperature particularly high). Atmospheric conditions can completely destroy image quality when using long focal lengths)

Last Modified By justin c at 19 Mar 2013 - 3:51 PM
GlennH
GlennH  91896 forum posts France1 Constructive Critique Points
19 Mar 2013 - 3:50 PM

... scrub that, it's on a tripod! Blush

Coleslaw
Coleslaw e2 Member 913403 forum postsColeslaw vcard Wales28 Constructive Critique Points
19 Mar 2013 - 3:52 PM

It could be anything!
Post some photos with EXIF info if you could.

cheddar-caveman
19 Mar 2013 - 4:07 PM

Now there's a challenge - EXIF? All the pictures are currently stored as RAW (.CR2) files. Presumably that will have all the capture data attached? Can I upload RAW images here or should I convert to .JPG or .TIFF?

Last Modified By cheddar-caveman at 19 Mar 2013 - 4:46 PM
GlennH
GlennH  91896 forum posts France1 Constructive Critique Points
19 Mar 2013 - 4:31 PM


Quote: Now there's a challenge - EXIF? I guess that is stored automatically with the RAW image? These files ar 25Mb+ ! Will this website allow such a large upload?

You can usually keep it embedded in a JPEG providing you check the right boxes.

cheddar-caveman
19 Mar 2013 - 4:51 PM

OK, here goes: The red coloured stuff is bailing twine - probably picked up from a field somewhere, and when focused in live view I could see the individual strands. Here it's just a "lump".
19-3-nest.jpg

lawbert
lawbert  71696 forum posts England15 Constructive Critique Points
19 Mar 2013 - 4:59 PM

Could an element in the lens be out of alignment?
But that shouldnt make a difference when critically focussed in live view?

cheddar-caveman
19 Mar 2013 - 5:07 PM

True. It's the same lens AND the image on the live view screen is taken from the sensor, not via the prism etc. so it is a puzzle!

Dave_Canon
19 Mar 2013 - 5:19 PM

With some DSLR's you cannot auto focus with an aperture larger than f5.6. In this particular case, your f4 lens is reduced to f5.6 when you add the 1.4x extender. This may at least result in AF being difficult even if still possible.

Dave

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