I forgot to consider that the focusing helical might have been damaged
by the impact that nailed the glass. I'd personally still consider such
a purchase but caution is advised.
Chuck Norcutt
On 1/13/2012 11:20 AM, Chuck Norcutt wrote:
> Actually, if you could get a really good deal on such a damaged lens it
> might be a good buy. The clear aperture of the 100/2 appears to be
> about 50mm. If the missing 1/2" (12.5mm) chunk was roughly circular the
> damaged area would only be 6-7% of the total glass area. Fill the
> damaged area with India ink to prevent it from transmitting light and
> the only side effects would be a 6-7% loss of light (trivial) and an
> increase in diffraction from the new edges introduced into the light
> path. But, given that the diaphragm and the lens cell edges are also
> diffracting edges the small increase due to the perimeter of the damaged
> area is also trivial. You'd be hard pressed to tell the difference
> between the damaged one and an undamaged one. The black spot in the
> glass would simply be a small obstruction in the light path. No
> different from and substantially smaller than the 25-35% area
> obstruction introduced in many mirror lenses by the secondary mirror.
>
> Chuck Norcutt
>
>
> On 1/13/2012 10:34 AM, Ken Norton wrote:
>> Beautiful condition. Perfect glass. The 1/2" chunk missing out of the
>> front element doesn't seem to affect image quality any...
>>
>> AG
>>
>> On 1/13/12, NSURIT@xxxxxxx<NSURIT@xxxxxxx> wrote:
>>>
>>> Well, according to the seller,
>>>
>>> "A beautiful lens in phenomenal condition overall. A must have for any
>>> collector or enthusiast. I have a modest price, good luck."
>>>
>>>
>>> In a message dated 1/13/2012 8:01:25 A.M. Central Standard Time,
>>> christrask@xxxxxxxxxxxxx writes:
>>>
>>> Saw that in the description and wondered about the price.
>>>
>>> Speaking of price, here's another one you might also want to pass up on
>>> #280805597834.
>>>
>>>
>>>
>>>
>>>
>>> --
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>>>
>>
>>
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