At 15:04 10/6/02, you wrote:
Mark wrote:
>I think their main purpose is to protect the rear element,
>but not from damage from being placed end down. If you look
>very carefully, as the lens is mounted on a body, you'll notice
>that the "horn(s)" line up with the bottom of the lens mount
>flange. The horns are there to protect the rear element from
>being damaged by the lens mount if you should happen to slip
>while mounting the lens. Only lenses which have the rear element
>recessed enough that the lens mount flange can't reach don't have
>the horns.
Take a look at the 35/2. Its rear element is as exposed, unrecessed and
vulnerable as the rear element of the 21/2. No horns. Same situation with
35~105/3.5-4.5.
I did, along with a few others from 18mm through 85mm:
18/3.5 MC: YES; wide tab.
24/2 MC: YES; wide tab.
35/2 (MC): NO.
35/2.8 Shift: NO.
50/1.2 (MC): YES; wide tab.
50/1.4 MC S/N 789,###: YES; wide tab.
50/1.4 MC S/N 1,055,###: YES; wide tab.
50/1.4 (MC) S/N 1,112,###: YES; pair of horns.
85/2 MC: NO (has pair of small interesting looking pegs though).
35-105/3.5~4.5 (MC) S/N 106,###: YES; wide tab (not very tall).
Note: (MC) = MC lens made after marking was discontinued.
50/1.4 MC: Included my third one with S/N < 800K.
35/2 (MC): Rear element does not protrude beyond its retaining ring,
although the retaining ring itself protrudes beyond the rear of the lens
mount. All the others with a wide tab (or horns) do protrude or are so
close to protrusion they could easily be abraded if set on a flat surface
at infinity focus.
35/2.8 Shift: With the shift mechanism between the lens cell and mounting
flange, the rear element is well inside the back of the lens. I suspect
this is the case with the other, 24/3.5 Shift, although I've never seen one.
35-105/3.5~4.5 MC: Has a very wide tab around the rear element, but it's
very short. Not as prominent or as noticeable.
Long lenses: None of my long lenses have these tabs or horns (85/2 MC,
135/2.8 MC, 200/4 MC, and 300/4.5 F.Zuiko). Their rear elemnts are always
recessed, even at infinity focus.
I've always been of the opinion these tabs and horns are intended to
protect the rear element in the event it is set on its rear without a
cap. Works only on a relatively rigid, flat surface though. It won't
protect it in a bag, or on a slightly uneven surface. None of them keep
the rear element very far above a rigid level surface.
I've seen lenses with scuffed rear elements that look as if they were
dumped into a camera bag without back cap. Lenses can still be very usable
with a very small chip or tiny scratch or two near the edge of the front
element. "Cleaning marks" consisting of thousands of microfine abrasions
over an area are a Bad Thing. They generate enormous flare, even though
they may not be as noticeable in examining the lens (dusty lenses will do
the same thing). Any rear element marks are **death** to a lens.
-- John
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