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Nikkor 105/2.5 aperture blades problem
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PostPosted: Thu Jan 04, 2018 9:38 pm    Post subject: Nikkor 105/2.5 aperture blades problem Reply with quote

Hello everyone, I recently acquired Nikkor-P 105/2.5 (mine has 9 :ap. blades, most of them are 6 blades), and when the aperture is opened all the way at 2.5 I can see the aperture blades inside - https://www.dropbox.com/s/re4ag11ccs81miv/IMG_20180102_150439.jpg?dl=0


I opened the lens, cleaned everything, reassembled the aperture blades, put everything back together (everything was assembled correctly, even when I opened it I couldn't find anything that was not put together right). It's still the same. A friend of mine has 6 blades version and when it's on 2.5 you can't see the blades, so I'm sure it's not supposed to be like it is on mine.

Does anyone know what can cause such a problem? Anyone met with something like this? Is there a way of adjusting the iris opening so it opens fully?


PostPosted: Thu Jan 04, 2018 10:41 pm    Post subject: Reply with quote

There are other lenses built like that. The important thing is that the open aperture blades don't block any of the light passing through the exit pupil. Look directly into the lens, not from an angle as in the photo showing the blades. You can see if the aperture blades block any of the circle of light exiting the lens.


PostPosted: Thu Jan 04, 2018 10:54 pm    Post subject: Reply with quote

visualopsins wrote:
There are other lenses built like that. The important thing is that the open aperture blades don't block any of the light passing through the exit pupil. Look directly into the lens, not from an angle as in the photo showing the blades. You can see if the aperture blades block any of the circle of light exiting the lens.


The blades block the light, the lens was not built like this, I compared it to friends 105/2.5 and the blades shouldn't be visible, not from direct angle, or under some weird angles, I just made that photo so it's clearly visible


PostPosted: Thu Jan 04, 2018 11:10 pm    Post subject: Reply with quote

Was it the same lens or a newer lens that you compared? The opening diameter should be equal, even if this lens shows more of the blades when wide open.
If the exact same, post some pics of the assembly process, perhaps we can see your error.
Another thing to check, is how small the aperture opening is when fully stopped down, and that the aperture steps with every detent of the aperture ring, if the opening is smaller, then the aperture assembly is clocked wrong somehow, but if it's the same size, and the steps are equal, then it's normal.


PostPosted: Fri Jan 05, 2018 12:04 am    Post subject: Reply with quote

This is the same lens I have, no aperture blades visible wide open

https://www.dropbox.com/s/hhe6ofg3f5ds2b3/received_1896157847061469.jpeg?dl=0

https://www.dropbox.com/s/vdhfl7i3m357sjh/received_1896157243728196.jpeg?dl=0

I'm going to disassemble it again tomorrow and take photos in the process, hopefully we can somehow fix it together


PostPosted: Fri Jan 05, 2018 1:00 am    Post subject: Reply with quote

Could there be more than one way to lay down the blades on their mounting pins? (EDIT, I guess we'll see! Smile )


PostPosted: Fri Jan 05, 2018 1:34 am    Post subject: Reply with quote

I have to P lenses and both have 6 blades and a Gauss type that has 7 blades. All three lenses open up so that you can no longer see the aperture blades. A suggestion would be to shoot your lens and your friends lens wide open and see if the exposure is the same. If it works, just shoot with it and hopefully it will have a unique look with the 9 aperture blades.
Pete


PostPosted: Fri Jan 05, 2018 2:06 am    Post subject: Reply with quote

This video might be helpful. Watch from 34:00 min.
https://www.youtube.com/watch?v=QwiCbkXXHus

good luck!


PostPosted: Fri Jan 05, 2018 2:40 am    Post subject: Reply with quote

Great video! Reopening the lens may reveal more. Another possibility, aperture comes from another lens.