What kind of lenses are these? If they are A series or newer I would
suggest putting the lens into A and see if the results are the same, since
when the lens is in A that lever is not used (the MZ-50 and MZ-30 are good
examples of this). If the difference is still there then it's something to
do with the lenses transmitting different amounts of light due to coatings,
number of elements, etc. If it's gone then it probably is the lever.
I don't have any experience taking apart A series or newer lenses, but I
have taken apart M and K series. Basically unscrew the screws on the mount
on the back of the lens, some lenses have them on the part that sticks into
the camera too. Once those are off you can take off the mount. Then you
can remove the aperture ring (be sure not to lose the little ball bearing
that makes the aperture click!) From there you can see where this lever is
linked directly to the aperture ring. That's as far as I have taken any
lens apart, because what I was fixing as a binding/stubborn aperture ring
by removing all the original, dried up grease and put a simular lubricant
on and put it back together.
A series lenses are much nastier I hear. First, you have to deal with the
A contacts, and secondly you have to deal with the springs and buttons that
go with the A button, and that can be almost impossible to get back
together (or so I hear).
Todd
At 10:32 AM 5/10/01 -0700, you wrote:
> Hi again,
>
>another question to check out the Pentax Data Base that is YOU.
>Situation is: comparing three of my lenses with fixed aperture (let's
>say: 5.6), the light meter gives on all three of them a different
>exposure time. That is: 50mm OK, 85mm +1 stop, 135mm +1/2 stop. After
>extensive comparisons in which all possible other explanations were
>ruled out, it left me with the only remaining cause: the 'pen' inside
>the mount of the lens that mechanically tells the camera what aperture
>is momentarily in use is not in proper place in two of the lenses.
>
>Now here's my question: is it possible to open up the rear of the lens
>myself, adjust the relative position of the 'pen' a little and at the
>same time be reasonably confident to end up with a working lens?
>
>Is there anybody out there who has had a similar problem and/or who has
>had the guts to rip open one of their lenses? - how did you fare?
>
>Maybe it's a good idea for anybody with ambitions to produce an
>illustrated HOW TO ... guide on internet...
>
>Thanks for reading, thinking and reacting,
>Hugo.
>
>__________________________________________________
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>Yahoo! Auctions - buy the things you want at great prices
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>-
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