fuzzy edges wide open...why?

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my latest aquisition is a 28/2.8 lens.
when used at 2.8 the edges are very blurry but when stopped down even a bit the edges clear up nicely.

what would cause this?
 
4609864665_27b04461a5_b.jpg
 
It seems fuzzy of the the left, more than the right. Even taking different distances to subjects into account. I´ve had this once, turned out elements were off kilter. Could never really get one side of the picture in focus with shallow DoF (wide open). IMO its broken and needs a CLA.
 
looks like decentering, in one or more of the fixed elements. In your example it's more pronounced on the left, than the top, for example.

I'd return it, or possibly get try to get it repaired by a *very* experienced tech with that lens.
 
i actually like the 'look' of the fuzzy edges and have been thinking about keeping the lens as is...make it a special purpose lens.
 
In the picture shown, the left side is fuzzier than the right side. Usually that means one of the elements is miscentered or not pressed into place correctly. I've seen some CLA'd lenses doing this, the element had to be pushed into place with a fair bit of force before tightening with the retaining ring.
 
Joe, I just looked through some of my images wide open with a similar lens (Canon 28), and the edges start to soften about 3/4 from the center, but nothing like that. And that's on 35mm film. On a cropped sensor, I would expect to see very little blurriness if the lens elements were in the right place. I can email examples if you want. I think yours needs some tlc.
 
Something wrong with the lens, Joe. The fuzzy-ness is not symmetric.

Also, if it's the Canon, it should be way sharper also wide open, I have a systematic test on my smugmug site, if you are interested.
 
I had one like this but it was just foreground bokeh (sp?)(wide open). Shoot a flat wall with patterned wallpaper before you jump off a bridge.
 
Mike

Mike

Just curious, what version is yours, 1,2 or 3?

Joe, I just looked through some of my images wide open with a similar lens (Canon 28), and the edges start to soften about 3/4 from the center, but nothing like that. And that's on 35mm film. On a cropped sensor, I would expect to see very little blurriness if the lens elements were in the right place. I can email examples if you want. I think yours needs some tlc.
 
i may just send it in to someone for a look see.
i paid next to nothing for it so even with a repair charge added it would be still be a reasonable price for me.
 
i actually like the 'look' of the fuzzy edges and have been thinking about keeping the lens as is...make it a special purpose lens.
I have one just like that, but it never sharpens up. I made the decision like you - special purposes! Great minds think alike, I hear.
 
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