Name this lens defect

[sam_crater]

Can anyone tell from this photo what's wrong with this lens? It

doesn't look like separation to me because it doesn't have any

reflectivity to it that I can see. Might be a chip, but the edge is

slightly blurry looking which doesn't seem right for a chip. It's

somewhere inside the front element and I can't get at it by just

removing it from the shutter. It looks sort of like it got burnt.

Anybody have a guess?<div></div>

[peter_white2]

I don't see anything unusual.

[sam_crater]

If you look at the top of the actual aperture you can see a small dark arc sticking down whick is the problem. It's definitely a defect.

[andrewlamb]

Isn't that a shadow?

[sam_crater]

No, its really a defect. I have the lens in hand so it's not just an artifact in the photo.

[sam_crater]

Sorry, I could have made this more clear in the first place. Now I added some arrows:<div></div>

[dan_fromm2]

Small separation with a touch of Schneideritis. Give it two aspirins, put it to bed for the night, and report back tomorrow if its condition has deteriorated.

[sam_crater]

Thanks Dan, have you seen separation that has that opaque and dark look? I though separation was supposed to look more like a flattened bubble inside the lens.

[peter_white2]

I don't have any idea what it is. But I do have a suggestion. Look through the lens as you slowly close the diaphram. See if there's an aperture where the defect isn't in the light path. If that aperture is f:22 or smaller, you can probably ignore the defect, unless it's an indication that something else is wrong with the lens. A few test images will tell you that. But if it's just that darkening, and if the darkening isn't in the light path at any aperture you would shoot at, it's of no consequence.

[conrad_hoffman]

Separation can be dark, light, or just a line, depending on degree and lighting. Unfortunately, it rarely has the uniform curvature seen here. I have an enlarging lens with a nearly identical appearing defect, and it's a fracture of an internal element. Disassembly is the only way to know for sure.

[jackflesher]

Looks like a chipped internal element to me...

[sam_crater]

Thanks everyone. I'm going to conclude it's a chip or fracture of some kind. It's still a good lens if one doesn't use the very limit of coverage in that direction.

[kelly_flanigan1]

Sam its just a "crater" defect :) OK bad pun! Maybe you can coin a new photo term..:)

[sam_crater]

Keep your day job Kelly. :|