Westminster fountain at sunset

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I've had this lens for a couple of years, but am really struggling to get sharp pictures now. I've tried it on a 400D and a 7D and both show the same results.

I had the problem with it getting stuck at the end of the zoom range and so had to take it apart to repair it, but it hasn't been the same since. (Note that this repair leaves all the optics intact, it just involves the assembly around it)

It isn't even like the focus is out a little, some shots have nothing showing as sharp, whereas others can be fairly alright.

I've tried the lens focus adjustment on the 7D but it seems fine on a tripod, just not in real life.

Any advice?

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I assume you mean getting stuck at the end of the focus (not zoom) range? Assuming the lens is properly repaired and as you say focuses correctly when on a tripod, photographing stationationary objects -- my best guess is that you are just having a technique issue with the extremely shallow depth of field. If your subject is further way/you use a smaller aperture (i.e. you increase the depth of field), are your photos sharp? –  Patrick Hurley Dec 9 '13 at 11:05
    
@PatrickHurley it appears that no parts of the image are in focus when used "on the move" so it isn't a depth of field being off issue. (Shutter speed is high enough that it isn't motion) blur. –  ck01 Dec 9 '13 at 12:02
    
What Tv are you using when 'on the move?' It may not be a focus issue at all. –  Michael Clark Dec 9 '13 at 13:06
    
@MichaelClark Some of the shots are 1/250 or better, static camera and subject, so not motion blur. –  ck01 Dec 9 '13 at 13:41

1 Answer 1

Adjusting the focus collar that gets bent when this lens is dropped with the focus set to anything other than infinity can leave the elements it supports decentered or even slightly tilted. With such a shallow depth of field any defects in adjustment are very easy to spot when using wider apertures. Your lens either needs a trip to a Canon Service Center or a replacement. It's about 50/50 which will cost less.

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I had wondered if it could be an alignment issue. If it is knackered then I might try the nifty-50 as it will be cheaper than a repair or replacement for mine... –  ck01 Dec 9 '13 at 12:03

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