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12-13-2020, 11:21 AM   #1
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Will K-S2 with aperture block failure function properly with the DA 55 to 300 PLM ?

I remember reading this somewhere but I just wanted to verify it , and if so , why bother to do a solenoid repair if my old manual Takumar lenses , full manual lenses , and the newer electronic aperture lenses work in spite of it ?
I have a chance to buy back my beloved K-S2 for $50 and can live with its limitations in spite of the problem if so.
Just wanting some clarity on this.

12-13-2020, 11:44 AM - 1 Like   #2
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It should! Be sure to apply firmware update.
12-13-2020, 11:54 AM - 1 Like   #3
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Yes, I can assure you, the KS-2 works with all PLM lenses
12-13-2020, 01:34 PM   #4
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Since the aperture block which is failing is purely mechanical (pressing on the lever), I don't see how it could prevent KAF4 lenses from setting aperture.

Besides, I have seen report of people which the aperture block failed while using exclusively that lens. Which means that the aperture block was unused, like with K and M lenses ; one of the reasons for it to fail.

12-13-2020, 01:54 PM - 1 Like   #5
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KAF4 lenses should be supported on the K-S2 with the appropriate firmware update. The aperture is controlled eloctromagnetically within the lens on KAF4 lenses and not by the lever on the camera body.

Not all PLM lenses (autofocus motor) are KAF4 mount lenses and still have an aperture lever on the lens.
12-14-2020, 11:16 AM   #6
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QuoteOriginally posted by Not a Number Quote
KAF4 lenses should be supported on the K-S2 with the appropriate firmware update. The aperture is controlled eloctromagnetically within the lens on KAF4 lenses and not by the lever on the camera body.

Not all PLM lenses (autofocus motor) are KAF4 mount lenses and still have an aperture lever on the lens.
As far as I have understood this, the PLM (PuLse-Motor) is an in-lens motor which works instead of the aperture-lever?

So the other KAF4 lens which I know about is the D-FA* 50mm f1,4 SDM.

Here we have KAF4 with the PLM-Motor for aperture but an SDM Motor for AF:

The electro-magnetic diaphrag-controll is show HERE

Text for it:
This mechanism performs diaphragm control operations by receiving electronic signals from the camera body and shifting the aperture blades with the driving motor built into the lens. It lets the user change aperture settings more flexibly during movie recording, because it operates very quietly by minimizing the diaphragm control noise that otherwise could be recorded in movie clips. It also controls aperture more accurately to assure stable, high-precision exposure control, especially when an AF rear converter is used for shooting.
(scroll down to Electromagnetic Diapragm Control Mechanism)
12-14-2020, 12:13 PM   #7
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PLM refers to the linear pulse type motor that drive the auto-focus group. KAF4 lenses also have an electromagnetic mechanism that moves the aperture that is separate from the focusing motor.

So you can have a PLM lens that is KAF4, but it doesn't have to be. And KAF4 lenses don't have to have PLM focusing motors.

12-14-2020, 05:16 PM   #8
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My thought on this is...ok , so my solenoid is shot and doesn't function at all anymore. But.....I can still use my old Takumar lenses and also can shoot by setting the aperture on my manual lenses. And if the KAF4 lens works ....why bother with a repair and I will just shoot these type lenses !
I'm headed over to buy my old K-S2 back in a few minutes !
12-15-2020, 02:32 PM   #9
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QuoteOriginally posted by Ronald Oakes Quote
I'm headed over to buy my old K-S2 back in a few minutes !
Hope it hasn't sold yet. Good luck!
12-15-2020, 05:02 PM   #10
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QuoteOriginally posted by Not a Number Quote
Hope it hasn't sold yet. Good luck!
Nope....! Sold it for $125 and just bought it back 2 years later for $50
Works perfect with the DA 55-300 PLM......
My friend also got tired using it with manual lenses and has left Pentax for the Fuji system.
I'm happy as the K-S2 has always been my most favorite camera.
I did have to update the firmware.

Last edited by Ronald Oakes; 12-15-2020 at 05:16 PM.
12-19-2020, 11:11 PM - 1 Like   #11
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50$ for a K-S2, even with aperture block failure, is an absolute bargain. Glad that your 55-300 PLM is perfectly functional with your K-S2!
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