fuzzy edges wide open...why?

[back alley]

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?

 

[crawdiddy]

are you using a lens hood?

 

[back alley]

are you using a lens hood?

no, but the lens is quite recessed into the barrel.

 

[back alley]

A sh!tty lens? Or an element out of whack.

the lens was cla'd maybe a yesr or so ago (according to the seller).

after 2.8 it behaves nicely...

 

[back alley]

 

[Mackinaw]

....what would cause this?

A poor optical design.

Jim B.

 

[Ezzie]

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.

 

[Pablito]

Looks like the lens is out of whack.

 

[back alley]

A poor optical design.

Jim B.

very helpful jim...

 

[ampguy]

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.

 

[back alley]

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.

 

[Sonnar Brian]

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.

 

[MikeL]

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.

 

[ferider]

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.

 

[charjohncarter]

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.

 

[ampguy]

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.

 

[ampguy]

example of a v2 wide open:

 

[FrankS]

Perhaps time for the much maligned brick wall shot?

 

[back alley]

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.

 

[januaryman]

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.