Analog film photography and cameras

don't know what the effect is called, but i've achieved a similar, albeit more exaggerated one using an enlarger without a negative carrier - i.e. different parts of the negative are different distances away from the bulb/lens rendering the edges of the photo with this circular blur kind of thing!

Like this photo from a fellow forumenger?

http://www.flickr.com/photos/27302326@N08/3570000003/in/set-72157616507813195/

I've had that happen too, but of course only with older lenses. I was surprised to have it happen to me when using my Mamiya C3 with 80mm f2.8 black lens. I'd been unconcerned when it was from pre-war lenses (either of the World Wars), but didn't think it would happen to the coated Mamiya lenses.

In portraits, its quite beautiful, though a bit disconcerting, as you can't plan for it with any exactitude.