What is wrong with this lens? Delamination?

[leif_goodwin8]

<p>I have an old 60mm F2.8 AF micro lens, and when I look through the rear elements, I see a ring of mistiness. There seems to be a slight colour to the ring. It appears to be on one of the fixed elements inside the lens i.e. not the rearmost one, but close to it. The mistiness is at the edge of the elements, and perfectly round. When I view through the lens, from the front with the aperture wide open, I see round the edge of the image a misty ring, almost as if there is a thin round ring of vaseline.<br /> Does anyone know for sure what this is? I do not think it is fungus, having seen a few cases of that on optics. (Totally wrong appearance i.e. not cobwebby and white.) I suspect this is delamination of a rear lens group. I've seen that on a Nikon diopter, and you get a coloured ring where the delamination occurs (colours due to interference I guess).<br /> Oddly enough, according to the lens cross section on the Nikon UK site, there looks to be only one cemented lens group, and that might move, whereas the 'damaged' element/group does not move.<br /> And as an aside, and having bought the latest 60mm micro lens, why oh why do Nikon have to downgrade the mechanics on micro lenses, by reducing the focus throw to a ridiculous degree, and removing the aperture ring? Marketing is my guess.</p>

[dcphotography]

<p>Nikon will no longer be making lenses with aperture rings (or, I'd imagine, only if they're specialty lenses. Even then, I doubt it). Many modern lenses have a short focus throw nowadays, since AF has mostly taken over.</p>

<p>I don't know about this mistiness problem, though.</p>

[keith_b1]

<p>From your description, it sounds exactly like classic delamination... caused by failure of the seal around the cemented elements. </p>

[leif_goodwin8]

<p>Thanks for the answers. Oh well!</p>

<p>Regarding AF, you would think that AF speed would be secondary to effective operation as a micro lens, given that AF is near useless for macro shooting.</p>