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70-200 2.8 II has a small focal point

Dolsen
Apprentice

My 70-200 Lens has no issues with auto focus and is crystal clear however it now seems to only have a very small area in sharp focus even at different apetures. It's not happening on ever single photo but it's becoming more frequent. Any idea of what might be the issue? 7U8A0361.jpg

5 REPLIES 5

diverhank
Authority

Depth of field varies by a combination of aperture, distance from camera to subject and the focal length (e.g. @ 200mm).  The picture you posted has a FL of 90mm and aperture of f/2.8.  Not sure what the distance to subject was.

 

You can use a number depth of field calculator available online to calculate the depth of field to see if there is anything odd with what you've got with the lens.  Here I used one called depth of field simulator (dofsimulator).  Guessing that this was taken at 5 feet away, here's the result: in focus 0.9 inch in front of point of focus and 0.9 inch behind...so your picture looks consistent.  The DOF gets less as you move closer and even less as you zoom in closer (e.g. 200mm instead of 90mm).

 

Capture.JPG

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ebiggs1
Legend

Not exactly sure where your focus point was, her face I assume.  Your DOF is small of course but you may have also have not been square to the subject.  This will cause what looks like OOF at the edges.

EB
EOS 1DX and 1D Mk IV and several lenses!

Dolsen
Apprentice
Hey guys thanks for commenting, I worked it out. The screws were loose in the connector plate thing on the lens ( I think it’s called ) tightened them up and it’s all good now!


@Dolsen wrote:
Hey guys thanks for commenting, I worked it out. The screws were loose in the connector plate thing on the lens ( I think it’s called ) tightened them up and it’s all good now!

That is extraordinary.  I would be inclined to send the lens to Canon for a cleaning and complete checkout.

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teleworm1337
Apprentice

Not exactly sure where your focus point was, her face I assume.  Your DOF is small of course but you may have also have not been square to the subject.  This will cause what looks like OOF at the edges. (Removed Link as per Forum Guidelines) 

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